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Bulletin of the Global Volcanism Network

All reports of volcanic activity published by the Smithsonian since 1968 are available through a monthly table of contents or by searching for a specific volcano. Until 1975, reports were issued for individual volcanoes as information became available; these have been organized by month for convenience. Later publications were done in a monthly newsletter format. Links go to the profile page for each volcano with the Bulletin tab open.

Information is preliminary at time of publication and subject to change.

Recently Published Bulletin Reports

Kadovar (Papua New Guinea) Intermittent ash plumes and persistent summit thermal anomalies, January-June 2020

Sangay (Ecuador) Daily ash plumes and frequent pyroclastic flows produce ashfall and lahars, January-June 2020

Karangetang (Indonesia) Incandescent block avalanches through mid-January 2020; crater anomalies through May

Masaya (Nicaragua) Lava lake level drops but remains active through May 2020; weak gas plumes

Shishaldin (United States) Intermittent thermal activity and a possible new cone at the summit crater during February-May 2020

Krakatau (Indonesia) Strombolian explosions, ash plumes, and crater incandescence during April 2020

Taal (Philippines) Eruption on 12 January with explosions through 22 January; steam plumes continuing into March

Unnamed (Tonga) Additional details and pumice raft drift maps from the August 2019 submarine eruption

Klyuchevskoy (Russia) Strombolian activity November 2019 through May 2020; lava flow down the SE flank in April

Nyamuragira (DR Congo) Intermittent thermal anomalies within the summit crater during December 2019-May 2020

Nyiragongo (DR Congo) Activity in the lava lake and small eruptive cone persists during December 2019-May 2020

Kavachi (Solomon Islands) Discolored water plumes seen using satellite imagery in 2018 and 2020



Kadovar (Papua New Guinea) — July 2020 Citation iconCite this Report

Kadovar

Papua New Guinea

3.608°S, 144.588°E; summit elev. 365 m

All times are local (unless otherwise noted)


Intermittent ash plumes and persistent summit thermal anomalies, January-June 2020

The steeply sloped 1.4-km-diameter Kadovar Island is located in the Bismark Sea offshore from the mainland of Papua New Guinea about 25 km NNE from the mouth of the Sepik River. Its first confirmed observed eruption began in early January 2018, with ash plumes and lava extrusion resulting in the evacuation of around 600 residents from the N side of the island (BGVN 43:03). A dome appeared at the base of the E flank during March-May 2018 (Planka et al., 2019); by November activity had migrated to a new dome growing near the summit on the E flank. Pulsating steam plumes, thermal anomalies, and periodic ash emissions continued throughout 2019 (BGVN 44:05, 45:01), and from January-June 2020, the period covered in this report. Information was provided by the Rabaul Volcano Observatory (RVO), the Darwin Volcanic Ash Advisory Center (VAAC), satellite sources, and photographs from visitors.

Activity during January-June 2020. Intermittent ash plumes, pulsating gas and steam plumes, and thermal anomalies continued at Kadovar during January-June 2020. MIROVA thermal data suggested persistent low-level anomalies throughout the period (figure 45). Sentinel-2 satellite data confirmed thermal anomalies at the summit on 5 and 25 January 2020, and an ash emission on 20 January (figure 46). Persistent pulsating steam plumes were visible whenever the skies were clear enough to see the volcano.

Figure (see Caption) Figure 45. Persistent low-level thermal activity at Kadovar was recorded in the MIROVA graph of radiative power from 2 July 2019 through June 2020. The island location is mislocated in the MIROVA system by about 5.5 km SE due to older mis-registered imagery; the anomalies are all on the island. Courtesy of MIROVA.
Figure (see Caption) Figure 46. Sentinel-2 satellite data confirmed thermal anomalies at the summit of Kadovar on 5 (left) and 25 January 2020, and an ash emission and steam plume that drifted SE on 20 January (center). Pulsating steam-and-gas emissions left a trail in the atmosphere drifting SE for several kilometers on 25 January (right). Left image uses Atmospheric penetration rendering (bands 12, 11, 8a), center and right images use Natural color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

On 2 February 2020 the Darwin VAAC reported a minor eruption plume that rose to 1.5 km altitude and drifted ESE for a few hours. Another plume was clearly discernible in satellite imagery on 5 February at 2.1 km altitude moving SE. RVO issued an information bulletin on 7 February reporting that, since the beginning of January, the eruption had continued with frequent Vulcanian explosions from the Main Vent with a recurrence interval of hours to days. Rocks and ash were ejected 300-400 m above the vent. Rumbling could be heard from Blupblup (Rubrub) island, 15 km E, and residents there also observed incandescence at night. On clear days the plume was sometimes visible from Wewak, on the mainland 100 km W. Additional vents produced variable amounts of steam. The Darwin VAAC reported continuous volcanic ash rising to 1.5 km on 22 February that extended ESE until it was obscured by a meteoric cloud; it dissipated early the next day. A small double ash plume and two strong thermal anomalies at the summit were visible in satellite imagery on 24 February (figure 47).

Figure (see Caption) Figure 47. Ash emissions and thermal anomalies continued at Kadovar during February 2020. Two small plumes of ash or dense steam rose from the summit on 24 February 2020, seen in this Natural color rendering (bands 4, 3, 2) on the left. The same image rendered in Atmospheric penetration (bands 12, 11, 8a) on the right shows two thermal anomalies in the same locations as the ash plumes. Courtesy of Sentinel Hub Playground.

The Darwin VAAC reported continuous ash emissions beginning on 13 March 2020 that rose to 1.5 km altitude and drifted SE. The plume was visible intermittently in satellite imagery for about 36 hours before dissipating. During April, pulsating steam plumes rose from two vents at the summit, and thermal anomalies appeared at both vents in satellite data (figure 48). Small but distinct SO2 anomalies were visible in satellite data on 15 and 16 April (figure 49).

Figure (see Caption) Figure 48. Steam plumes and thermal anomalies continued at Kadovar during April 2020. Top: A thermal anomaly at the summit accompanied pulsating steam plumes that drifted several kilometers SE before dissipating on 4 April 2020. Bottom left: Two gas-and-steam plumes drifted E from the summit on 9 April. Bottom right: Two adjacent thermal anomalies were present near the summit on 19 April. Top and bottom right images use Atmospheric penetration rendering (bands 12, 11, 8a), bottom left image uses Natural color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 49. Small but distinct SO2 anomalies were detected at Kadovar on 15 and 16 April 2020 with the TROPOMI instrument on the Sentinel-5P satellite. Nearby Manam often produces larger SO2 plumes that obscure evidence of activity at Kadovar. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Two summit vents remained active throughout May and June 2020, producing pulsating steam plumes that were visible for tens of kilometers and thermal anomalies visible in satellite data (figure 50). A strong thermal anomaly was visible beneath meteoric clouds on 8 June.

Figure (see Caption) Figure 50. During May and June 2020 thermal and plume activity continued at Kadovar. Top: Gas-and-steam plumes drifted NW from two sources at the summit of Kadovar on 19 May 2020. Bottom left: Two thermal anomalies marked the E rim of the summit crater on 28 June 2020. Bottom right: A zoomed out view of the same 28 June image shows pulsating steam plumes drifting 10 km NW from Kadovar. Top image is Natural color rendering (bands 4, 3, 2). Bottom images are Atmospheric penetration rendering (bands 12, 11, 8a) of Sentinel-2 images. Courtesy of Sentinel Hub Playground.

Visitor observations on 21 October 2019. Claudio Jung visited Kadovar on 21 October 2019. Shortly before arriving on the island an ash plume rose tens of meters above the summit and drifted W (figure 51). From the NW side of the summit crater rim, Jung saw the actively growing dome on the side of a larger dome, and steam and gas issuing from the growing dome (figure 52). The crater rim was covered with dead vegetation, ash, and large bombs from recent explosions (figure 53). The summit dome had minor fumarolic activity around the summit area and dead vegetation halfway up the flank (figure 54) while the fresh blocky lava of the actively growing dome on the E side of the summit produced significant steam and gas emissions. The growing dome produced periodic pulses of dense steam during his visit (figure 55).

Figure (see Caption) Figure 51. Views looking S show the shoreline dome at the base of the E flank of Kadovar that was active during March-May 2018 (left), and an ash plume drifting W from the summit dome located on the E side of the summit crater (right) on 21 October 2019. Copyrighted photos courtesy of Claudio Jung, used with permission.
Figure (see Caption) Figure 52. A panorama looking SE from the crater rim of Kadovar on 21 October 2019 shows the actively growing dome on the far left with a narrow plume of steam and gas being emitted. A large dome fills the summit crater; the crater rim is visible on the right. Copyrighted photo courtesy of Claudio Jung, used with permission.
Figure (see Caption) Figure 53. The crater rim of Kadovar on 21 October 2019 was covered with dead vegetation, ash, and large bombs from recent explosions. Person is sitting on a large bomb; weak fumarolic activity is visible along the rim. Copyrighted photo courtesy of Claudio Jung, used with permission.
Figure (see Caption) Figure 54. The summit dome of Kadovar on 21 October 2019 had minor fumarolic activity around most of its summit and dead vegetation half-way up the flank (left). The dead tree stumps suggest that vegetation covered the lower half of the dome prior to the eruption that began in January 2018. The fresh blocky lava of the actively growing dome on the E side of the summit dome produced significant steam and gas emissions (right). Copyrighted photos courtesy of Claudio Jung, used with permission.
Figure (see Caption) Figure 55. Dense steam from the growing dome on the E side of the summit drifted W from Kadovar on 21 October 2019. Copyrighted photo courtesy of Claudio Jung, used with permission.

Reference: Planka S, Walter T R, Martinis S, Cescab S, 2019, Growth and collapse of a littoral lava dome during the 2018/19 eruption of Kadovar Volcano, Papua New Guinea, analyzed by multi-sensor satellite imagery, Journal of Volcanology and Geothermal Research, v. 388, 15 December 2019, 106704, https://doi.org/10.1016/j.jvolgeores.2019.106704.

Geologic Background. The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. It is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. Prior to an eruption that began in 2018, a lava dome formed the high point of the andesitic volcano, filling an arcuate landslide scarp open to the south; submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. A period of heightened thermal phenomena took place in 1976. An eruption began in January 2018 that included lava effusion from vents at the summit and at the E coast.

Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Claudio Jung (URL: https://www.instagram.com/jung.claudio/).


Sangay (Ecuador) — July 2020 Citation iconCite this Report

Sangay

Ecuador

2.005°S, 78.341°W; summit elev. 5286 m

All times are local (unless otherwise noted)


Daily ash plumes and frequent pyroclastic flows produce ashfall and lahars, January-June 2020

Frequent activity at Ecuador's Sangay has included pyroclastic flows, lava flows, ash plumes, and lahars reported since 1628. Its remoteness on the east side of the Andean crest make ground observations difficult; remote cameras and satellites provide important information on activity. The current eruption began in March 2019 and continued through December 2019 with activity focused on the Cráter Central and the Ñuñurco (southeast) vent; they produced explosions with ash plumes, lava flows, and pyroclastic flows and block avalanches. In addition, volcanic debris was remobilized in the Volcan river causing significant damming downstream. This report covers ongoing similar activity from January through June 2020. Information is provided by Ecuador's Instituto Geofísico, Escuela Politécnica Nacional (IG-EPN), and a number of sources of remote data including the Washington Volcanic Ash Advisory Center (VAAC), the Italian MIROVA Volcano HotSpot Detection System, and Sentinel-2 satellite imagery. Visitors also provided excellent ground and drone-based images and information.

Throughout January-June 2020, multiple daily reports from the Washington Volcanic Ash Advisory Center (VAAC) indicated ash plumes rising from the summit, generally 500-1,100 m. Each month one or more plumes rose over 2,000 m. The plumes usually drifted SW or W, and ashfall was reported in communities 25-90 km away several times during January-March and again in June. In addition to explosions with ash plumes, pyroclastic flows and incandescent blocks frequently descended a large, deep ravine on the SE flank. Ash from the pyroclastic flows rose a few hundred meters and drifted away from the volcano. Incandescence was visible on clear nights at the summit and in the ravine. The MIROVA log radiative power graph showed continued moderate and high levels of thermal energy throughout the period (figure 57). Sangay also had small but persistent daily SO2 signatures during January-June 2020 with larger pulses one or more days each month (figure 58). IG-EPN published data in June 2020 about the overall activity since May 2019, indicating increases throughout the period in seismic event frequency, SO2 emissions, ash plume frequency, and thermal energy (figure 59).

Figure (see Caption) Figure 57. This graph of log radiative power at Sangay for 18 Aug 2018 through June 2020 shows the moderate levels of thermal energy through the end of the previous eruption in late 2018 and the beginning of the current one in early 2019. Data is from Sentinel-2, courtesy of MIROVA.
Figure (see Caption) Figure 58. Small but persistent daily SO2 signatures were typical of Sangay during January-June 2020. A few times each month the plume was the same or larger than the plume from Columbia’s Nevado del Ruiz, located over 800 km NE. Image dates are shown in the header over each image. Courtesy of NASA’s Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 59. A multi-parameter graph of activity at Sangay from May 2019 to 12 June 2020 showed increases in many types of activity. a) seismic activity (number of events per day) detected at the PUYO station (source: IG-EPN). b) SO2 emissions (tons per day) detected by the Sentinel-5P satellite sensor (TROPOMI: red squares; source: MOUNTS) and by the IG-EPN (DOAS: green bars). c) height of the ash plumes (meters above crater) detected by the GOES-16 satellite sensor (source: Washington VAAC). d) thermal emission power (megawatt) detected by the MODIS satellite sensor (source: MODVOLC) and estimate of the accumulated lava volume (million M3, thin lines represent the error range). Courtesy of IG-EPN (Informe Especial del Volcán Sangay - 2020 - N°3, “Actualización de la actividad eruptiva”, Quito, 12 de junio del 2020).

Activity during January-March 2020. IG-EPN and the Washington VAAC reported multiple daily ash emissions throughout January 2020. Gas and ash emissions generally rose 500-1,500 m above the summit, most often drifting W or SW. Ashfall was reported on 8 January in the communities of Sevilla (90 km SSW), Pumallacta and Achupallas (60 km SW) and Cebadas (35 km WNW). On 16 January ash fell in the Chimborazo province in the communities of Atillo, Ichobamba, and Palmira (45 km W). Ash on 28 January drifted NW, with minor ashfall reported in Púngala (25 km NW) and other nearby communities. The town of Alao (20 km NW) reported on 30 January that all of the vegetation in the region was covered with fine white ash; Cebadas and Palmira also noted minor ashfall (figure 60).

Figure (see Caption) Figure 60. Daily ash plumes and repeated ashfall were reported from Sangay during January 2020. Top left: 1 January 2020 (INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-2, JUEVES, 2 ENERO 2020). Top right: 20 January 2020 (INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-21, MARTES, 21 ENERO 2020). Bottom left: 26 January-1 February 2020 expedition (Martes, 18 Febrero 2020 12:21, EXPEDICIÓN AL VOLCÁN SANGAY). Bottom right: 30 January 2020, minor ashfall was reported in the Province of Chimborazo (#IGAlInstante Informativo VOLCÁN SANGAY No. 006, JUEVES, 30 ENERO 2020). Courtesy of IG-EPN.

A major ravine on the SE flank has been the site of ongoing block avalanches and pyroclastic flows since the latest eruption began in March 2019. The pyroclastic flows down the ravine appeared incandescent at night; during the day they created ash clouds that drifted SW. Satellite imagery recorded incandescence and dense ash from pyroclastic flows in the ravine on 7 January (figure 61). They were also reported by IG on the 9th, 13th, 26th, and 28th. Incandescent blocks were reported in the ravine several times during the month. The webcam captured images on 31 January of large incandescent blocks descending the entire length of the ravine to the base of the mountain (figure 62). Large amounts of ash and debris were remobilized as lahars during heavy rains on the 25th and 28th.

Figure (see Caption) Figure 61. Sentinel-2 satellite imagery of Sangay from 7 January 2020 clearly showed a dense ash plume drifting W and ash and incandescent material from pyroclastic flows descending the SE-flank ravine. Left image uses natural color (bands 4, 3, 2) rendering and right images uses atmospheric penetration (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 62. Pyroclastic flows at Sangay produced large trails of ash down the SE ravine many times during January 2020 that rose and drifted SW. Top left: 9 January (INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-9, JUEVES, 9 ENERO 2020). Top right: 13 January (INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-14, MARTES, 14 ENERO 2020). On clear nights, incandescent blocks of lava and pyroclastic flows were visible in the ravine. Bottom left: 16 January (INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-17, VIERNES, 17 ENERO 2020). Bottom right: 31 January (#IGAlInstante Informativo VOLCÁN SANGAY No. 007, VIERNES, 31 ENERO 2020). Courtesy of IG-EPN.

Observations by visitors to the volcano during 9-17 January 2020 included pyroclastic flows, ash emissions, and incandescent debris descending the SE flank ravine during the brief periods when skies were not completely overcast (figure 63 and 64). More often there was ash-filled rain and explosions heard as far as 16 km from the volcano, along with the sounds of lahars generated from the frequent rainfall mobilizing debris from the pyroclastic flows. The confluence of the Rio Upano and Rio Volcan is 23 km SE of the summit and debris from the lahars has created a natural dam on the Rio Upano that periodically backs up water and inundates the adjacent forest (figure 65). A different expedition to Sangay during 26 January-1 February 2020 by IG personnel to repair and maintain the remote monitoring station and collect samples was successful, after which the station was once again transmitting data to IG-EPN in Quito (figure 66).

Figure (see Caption) Figure 63. Hikers near Sangay during 9-17 January 2020 witnessed pyroclastic flows and incandescent explosions and debris descending the SE ravine. Left: The view from 40 km SE near Macas showed ash rising from pyroclastic flows in the SE ravine. Right: Even though the summit was shrouded with a cap cloud, incandescence from the summit crater and from pyroclastic flows on the SE flank were visible on clear nights. Courtesy of Arnold Binas, used with permission.
Figure (see Caption) Figure 64. The steep ravine on the SE flank of Sangay was hundreds of meters deep in January 2020 when these drone images were taken by members of a hiking trip during 9-17 January 2020 (left). Pyroclastic flows descended the ravine often (right), coating the sides of the ravine with fine, white ash and sending ash billowing up from the surface of the flow which resulted in ashfall in adjacent communities several times. Courtesy of Arnold Binas, used with permission.
Figure (see Caption) Figure 65. Debris from pyroclastic flows that descended the SE Ravine at Sangay was carried down the Volcan River (left) during frequent rains and caused repeated damming at the confluence with the Rio Upano (right), located 23 km SE of the summit. These images show the conditions along the riverbeds during 9-17 January 2020. Courtesy of Arnold Binas, used with permission.
Figure (see Caption) Figure 66. An expedition by scientists from IG-EPN to one of the remote monitoring stations at Sangay during 26 January-1 February 2020 was successful in restoring communication to Quito. The remote location and constant volcanic activity makes access and maintenance a challenge. Courtesy of IG-EPN (Martes, 18 Febrero 2020 12:21, EXPEDICIÓN AL VOLCÁN SANGAY).

During February 2020, multiple daily VAAC reports of ash emissions continued (figure 67). Plumes generally rose 500-1,100 m above the summit and drifted W, although on 26 February emissions were reported to 1,770 m. Ashfall was reported in Macas (40 km SE) on 1 February, and in the communities of Pistishi (65 km SW), Chunchi (70 km SW), Pumallacta (60 k. SW), Alausí (60 km SW), Guamote (40 km WNW) and adjacent areas of the Chimborazo province on 5 February. The Ecuadorian Red Cross reported ash from Sangay in the provinces of Cañar and Azuay (60-100 km SW) on 25 February. Cebadas and Guamote reported moderate ashfall the following day. The communities of Cacha (50 km NW) and Punín (45 km NW) reported trace amounts of ashfall on 29 February. Incandescent blocks were seen on the SE flank multiples times throughout the month. A pyroclastic flow was recorded on the SE flank early on 6 February; additional pyroclastic flows were observed later that day on the SW flank. On 23 February a seismic station on the flank recorded a high-frequency signal typical of lahars.

Figure (see Caption) Figure 67. Steam and ash could be seen drifting SW from the summit of Sangay on 11 February 2020 even though the summit was hidden by a large cap cloud. Ash was also visible in the ravine on the SE flank. Courtesy of Sentinel Hub Playground, natural color (bands 4, 3, 2) rendering.

A significant ash emission on 1 March 2020 was reported about 2 km above the summit, drifting SW. Multiple ash emissions continued daily during the month, generally rising 570-1,170 m high. An emission on 12 March also rose 2 km above the summit. Trace ashfall was reported in Cebadas (35 km WNW) on 12 March. The community of Huamboya, located 40 km ENE of Sangay in the province of Morona-Santiago reported ashfall on 17 March. On 19 and 21 March ashfall was seen on the surface of cars in Macas to the SE. (figure 68). Ash was also reported on the 21st in de Santa María De Tunants (Sinaí) located E of Sangay. Ash fell again in Macas on 23 March and was also reported in General Proaño (40 km SE). The wind changed direction the next day and caused ashfall on 24 March to the SW in Cuenca and Azogues (100 km SW).

Figure (see Caption) Figure 68. Ashfall from Sangay was reported on cars in Huamboya on 17 March 2020 (left) and in Macas on 19 March (right). Courtesy IG-EPN, (#IGAlInstante Informativo VOLCÁN SANGAY No. 024, MARTES, 17 MARZO 2020 and #IGAlInstante Informativo VOLCÁN SANGAY No. 025, JUEVES, 19 MARZO 2020).

Incandescence from the dome at the crater and on the SE flank was noted by IG on 3, 4, and 13 March. Remobilized ash from a pyroclastic flow was reported drifting SW on 13 March. The incandescent path of the flow was still visible that evening. Numerous lahars were recorded seismically during the month, including on days 5, 6, 8, 11, 15, 30 and 31. Images from the Rio Upano on 11 March confirmed an increase from the normal flow rate (figure 69) inferred to be from volcanic debris. Morona-Santiago province officials reported on 14 March that a new dam had formed at the confluence of the Upano and Volcano rivers that decreased the flow downstream; by 16 March it had given way and flow had returned to normal levels.

Figure (see Caption) Figure 69. Images from the Rio Upano on 11 March 2020 (left) confirmed an increase from the normal flow rate related to lahars from Sangay descending the Rio Volcan. By 16 March (right), the flow rate had returned to normal, although the large blocks in the river were evidence of substantial activity in the past. Courtesy of IG (#IGAlInstante Informativo VOLCÁN SANGAY No. 018, MIÉRCOLES, 11 MARZO 2020 and #IGAlInstante Informativo VOLCÁN SANGAY No. 023, LUNES, 16 MARZO 2020).

Activity during April-June 2020. Lahar activity continued during April 2020; they were reported seven times on 2, 5, 7, 11, 12, 19, and 30 April. A significant reduction in the flow of the Upano River at the entrance bridge to the city of Macas was reported 9 April, likely due to a new dam on the river upstream from where the Volcan river joins it caused by lahars related to ash emissions and pyroclastic flows (figure 70). The flow rate returned to normal the following day. Ash emissions were reported most days of the month, commonly rising 500-1,100 m above the summit and drifting W. Incandescent blocks or flows were visible on the SE flank on 4, 10, 12, 15-16, and 20-23 April (figure 71).

Figure (see Caption) Figure 70. A significant reduction in the flow of the Upano River at the entrance bridge to the city of Macas was reported on 9 April 2020, likely due to a new dam upstream from lahars related to ash emissions and pyroclastic flows from Sangay. Courtesy of IG-EPN (#IGAlInstante Informativo VOLCÁN SANGAY No. 032, JUEVES, 9 ABRIL 2020).
Figure (see Caption) Figure 71. Incandescent blocks rolled down the SE ravine at Sangay multiple times during April 2020, including on 4 April (left). Pyroclastic flows left two continuous incandescent trails in the ravine on 23 April (right). Courtesy of IG-EPN (INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-95, SÁBADO, 4 ABRIL 2020 and INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-114, JUEVES, 23 ABRIL 2020).

Activity during May 2020 included multiple daily ash emissions that drifted W and numerous lahars from plentiful rain carrying ash and debris downstream. Although there were only a few visible observations of ash plumes due to clouds, the Washington VAAC reported plumes visible in satellite imagery throughout the month. Plumes rose 570-1,170 m above the summit most days; the highest reported rose to 2,000 m above the summit on 14 May. Two lahars occurred in the early morning on 1 May and one the next day. A lahar signal lasted for three hours on 4 May. Two lahar signals were recorded on the 7th, and three on the 9th. Lahars were also recorded on 16-17, 20-22, 26-27, and 30 May. Incandescence on the SE flank was only noted three times, but it was cloudy nearly every day.

An increase in thermal and overall eruptive activity was reported during June 2020. On 1 and 2 June the webcam captured lava flows and remobilization of the deposits on the SE flank in the early morning and late at night. Incandescence was visible multiple days each week. Lahars were reported on 4 and 5 June. The frequent daily ash emissions during June generally rose to 570-1,200 m above the summit and drifted usually SW or W. The number of explosions and ash emissions increased during the evening of 7 June. IG interpreted the seismic signals from the explosions as an indication of the rise of a new pulse of magma (figure 72). The infrasound sensor log from 8 June also recorded longer duration tremor signals that were interpreted as resulting from the descent of pyroclastic flows in the SE ravine.

Figure (see Caption) Figure 72. Seismic and infrasound signals indicated increased explosive and pyroclastic flow activity at Sangay on 7-8 June 2020. Left: SAGA station (seismic component) of 7 and 8 June. The signals correspond to explosions without VT or tremor signals, suggesting the rise of a new magma pulse. Right: SAGA station infrasound sensor log from 8 June. The sharp explosion signals are followed a few minutes later (examples highlighted in red) by emergent signals of longer duration, possibly associated with the descent of pyroclastic material in the SE flank ravine. Courtesy if IG-EPN (Informe Especial del Volcán Sangay - 2020 - N°3, “Actualización de la actividad eruptiva”, Quito, 12 de junio del 2020).

On the evening of 8 June ashfall was reported in the parish of Cebadas and in the Alausí Canton to the W and SW of Sangay. There were several reports of gas and ash emissions to 1,770 m above the summit the next morning on 9 June, followed by reports of ashfall in the provinces of Guayas, Santa Elena, Los Ríos, Morona Santiago, and Chimborazo. Ashfall continued in the afternoon and was reported in Alausí, Chunchi, Guamote, and Chillanes. That night, which was clear, the webcam captured images of pyroclastic flows down the SE-flank ravine; IG attributed the increase in activity to the collapse of one or more lava fronts. On the evening of 10 June additional ashfall was reported in the towns of Alausí, Chunchi, and Guamote (figure 73); satellite imagery indicated an ash plume drifting W and incandescence from pyroclastic flows in the SE-flank ravine the same day (figure 74).

Figure (see Caption) Figure 73. Ashfall from Sangay was reported in Alausí (top left), Chunchi (top right) and Guamote (bottom) on 10 June 2020. Courtesy of IG-EPN (#IGAlInstante Informativo VOLCÁN SANGAY No. 049, MIÉRCOLES, 10 JUNIO 2020).
Figure (see Caption) Figure 74. Incandescent pyroclastic flows (left) and ash plumes that drifted W (right) were recorded on 10 June 2020 at Sangay in Sentinel-2 satellite imagery. Courtesy of Sentinel Hub Playground.

Ashfall continued on 11 June and was reported in Guayaquil, Guamote, Chunchi, Riobamba, Guaranda, Chimbo, Echandía, and Chillanes. The highest ash plume of the report period rose to 2,800 m above the summit that day and drifted SW. That evening the SNGRE (Servicio Nacional de Gestion de Riesgos y Emergencias) reported ash fall in the Alausí canton. IG noted the increase in intensity of activity and reported that the ash plume of 11 June drifted more than 600 km W (figure 75). Ash emissions on 12 and 13 June drifted SW and NW and resulted in ashfall in the provinces of Chimborazo, Cotopaxi, Tungurahua, and Bolívar. On 14 June, the accumulation of ash interfered with the transmission of information from the seismic station. Lahars were reported each day during 15-17 and 19-21 June. Trace amounts of ashfall were reported in Macas to the SE on 25 June.

Figure (see Caption) Figure 75. The ash plume at Sangay reported on 11 June 2020 rose 2.8 km above the summit and drifted W according to the Washington VAAC and IG (left). Explosions and high levels of incandescence on the SE flank were captured by the Don Bosco webcam (right). Courtesy of IG-EPN (#IGAlInstante Informativo VOLCÁN SANGAY No. 055, JUEVES, 11 JUNIO 2020 and INFORME DIARIO DEL ESTADO DEL VOLCÁN SANGAY No. 2020-164, VIERNES, 12 JUNIO 2020).

During an overflight of Sangay on 24 June IG personnel observed that activity was characterized by small explosions from the summit vent and pyroclastic flows down the SE-flank ravine. The explosions produced small gas plumes with a high ash content that did not rise more than 500 m above the summit and drifted W (figure 76). The pyroclastic flows were restricted to the ravine on the SE flank, although the ash from the flows rose rapidly and reached about 200 m above the surface of the ravine and also drifted W (figure 77).

Figure (see Caption) Figure 76. A dense ash plume rose 500 m from the summit of Sangay on 24 June 2020 and drifted W during an overflight by IG-EPN personnel. The aerial photograph is taken from the SE; snow-covered Chimborazo is visible behind and to the right of Sangay. Photo by M Almeida, courtesy of IG EPN (Jueves, 02 Julio 2020 10:29, INFORME DEL SOBREVUELO AL VOLCÁN SANGAY EL 24 DE JUNIO DE 2020).
Figure (see Caption) Figure 77. Pyroclastic flows descended the SE flank ravine at Sangay during an overflight by IG-EPN personnel on 24 June 2020. Ash from the pyroclastic flow rose 200 m and drifted W, and infrared imagery identified the thermal signature of the pyroclastic flow in the ravine. Photo by M Almeida, IR Image by S Vallejo, courtesy of IG EPN (Jueves, 25 Junio 2020 12:24, SOBREVUELO AL VOLCÁN SANGAY).

Infrared imagery taken during the overflight on 24 June identified three significant thermal anomalies in the large ravine on the SE flank (figure 78). Analysis by IG scientists suggested that the upper anomaly 1 (125°C) was associated with explosive activity that was observed during the flight. Anomaly 2 (147°C), a short distance below Anomaly 1, was possibly related to effusive activity of a small flow, and Anomaly 3 (165°C) near the base of the ravine that was associated with pyroclastic flow deposits. The extent of the changes at the summit of Sangay and along the SE flank since the beginning of the eruption that started in March 2019 were clearly visible when images from May 2019 were compared with images from the 24 June 2020 overflight (figure 79). The upper part of the ravine was nearly 400 m wide by the end of June.

Figure (see Caption) Figure 78. A thermal image of the SE flank of Sangay taken on 24 June 2020 indicated three thermal anomalies. Anomaly 1 was associated with explosive activity, Anomaly 2 was associated with effusive activity, and Anomaly 3 was related to pyroclastic-flow deposits. Image prepared by S Vallejo Vargas, courtesy of IG EPN (Jueves, 02 Julio 2020 10:29, INFORME DEL SOBREVUELO AL VOLCÁN SANGAY EL 24 DE JUNIO DE 2020).
Figure (see Caption) Figure 79. Aerial and thermal photographs of the southern flank of the Sangay volcano on 17 May 2019 (left: visible image) and 24 June 2020 (middle: visible image, right: visible-thermal overlay) show the morphological changes on the SE flank, associated with the formation of a deep ravine and the modification of the summit. Photos and thermal image by M Almeida, courtesy of IG EPN (Jueves, 02 Julio 2020 10:29, INFORME DEL SOBREVUELO AL VOLCÁN SANGAY EL 24 DE JUNIO DE 2020).

Geologic Background. The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.

Information Contacts: Instituto Geofísico, Escuela Politécnica Nacional (IG-EPN), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Arnold Binas (URL: https://www.doroadventures.com).


Karangetang (Indonesia) — June 2020 Citation iconCite this Report

Karangetang

Indonesia

2.781°N, 125.407°E; summit elev. 1797 m

All times are local (unless otherwise noted)


Incandescent block avalanches through mid-January 2020; crater anomalies through May

The Karangetang andesitic-basaltic stratovolcano (also referred to as Api Siau) at the northern end of the island of Siau, north of Sulawesi, Indonesia, has had more than 50 observed eruptions since 1675. Frequent explosive activity is accompanied by pyroclastic flows and lahars, and lava-dome growth has created two active summit craters (Main to the S and Second Crater to the N). Rock avalanches, observed incandescence, and satellite thermal anomalies at the summit confirmed continuing volcanic activity since the latest eruption started in November 2018 (BGVN 44:05). This report covers activity from December 2019 through May 2020. Activity is monitored by Indonesia's Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM, or the Center of Volcanology and Geological Hazard Mitigation), and ash plumes are monitored by the Darwin VAAC (Volcanic Ash Advisory Center). Information is also available from MODIS thermal anomaly satellite data through both the University of Hawaii's MODVOLC system and the Italian MIROVA project.

Increased activity that included daily incandescent avalanche blocks traveling down the W and NW flanks lasted from mid-July 2019 (BGVN 44:12) through mid-January 2020 according to multiple sources. The MIROVA data showed increased number and intensity of thermal anomalies during this period, with a sharp drop during the second half of January (figure 40). The MODVOLC thermal alert data reported 29 alerts in December and ten alerts in January, ending on 14 January, with no further alerts through May 2020. During December and the first half of January incandescent blocks traveled 1,000-1,500 m down multiple drainages on the W and NW flanks (figure 41). After this, thermal anomalies were still present at the summit craters, but no additional activity down the flanks was identified in remote satellite data or direct daily observations from PVMBG.

Figure (see Caption) Figure 40. An episode of increased activity at Karangetang from mid-July 2019 through mid-January 2020 included incandescent avalanche blocks traveling down multiple flanks of the volcano. This was reflected in increased thermal activity seen during that interval in the MIROVA graph covering 5 June 2019 through May 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 41. An episode of increased activity at Karangetang from mid-July 2019 through mid-January 2020 included incandescent avalanche blocks traveling up to 1,500 m down drainages on the W and NW flanks of the volcano. Top left: large thermal anomalies trend NW from Main Crater on 5 December 2019; about 500 m N a thermal anomaly glows from Second Crater. Top center: on 15 December plumes of steam and gas drifted W and SW from both summit craters as seen in Natural Color rendering (bands 4,3,2). Top right: the same image as at top center with Atmospheric penetration rendering (bands 12, 11, 8a) shows hot zones extending WNW from Main Crater and a thermal anomaly at Second Crater. Bottom left: thermal activity seen on 14 January 2020 extended about 800 m WNW from Main Crater along with an anomaly at Second Crater and a hot spot about 1 km W. Bottom center: by 19 January the anomaly from Second Crater appeared slightly stronger than at Main Crater, and only small anomalies appeared on the NW flank. Bottom right: an image from 14 March shows only thermal anomalies at the two summit craters. Courtesy of Sentinel Hub Playground.

A single VAAC report in early April noted a short-lived ash plume that drifted SW. Intermittent low-level activity continued through May 2020. Small SO2 plumes appeared in satellite data multiple times in December 2019 and January 2020; they decreased in size and frequency after that but were still intermittently recorded into May 2020 (figure 42).

Figure (see Caption) Figure 42. Small plumes of sulfur dioxide were measured at Karangetang with the TROPOMI instrument on the Sentinel-5P satellite multiple times during December 2019 (top row). They were less frequent but still appeared during January-May 2020 (bottom row). Larger plumes were also detected from Dukono, located 300 km ESE at the N end of North Maluku. Courtesy of Global Sulfur Dioxide Monitoring Page.

PVMBG reported in their daily summaries that steam plumes rose 50-150 m above the Main Crater and 25-50 m above Second Crater on most days in December. The incandescent avalanche activity that began in mid-July 2019 also continued throughout December 2019 and January 2020 (figure 43). Incandescent blocks from the Main Crater descended river drainages (Kali) on the W and NW flanks throughout December. They were reported nearly every day in the Nanitu, Sense, and Pangi drainages, traveling 1,000-1,500 m. Incandescence from both craters was visible 10-25 m above the crater rim most nights.

Figure (see Caption) Figure 43. Incandescent block avalanches descended the NW flank of Karangetang as far as 1,500 m frequently during December 2019 and January 2020. Left image taken 13 December 2019, right image taken 6 January 2020 by PVMBG webcam. Courtesy of PVMBG, Oystein Anderson, and Bobyson Lamanepa.

A few blocks were noted traveling 800 m down Kali Beha Barat on 1 December. Incandescence above the Main crater reached 50-75 m during 4-6 December. During 4-7 December incandescent blocks appeared in Kali Sesepe, traveling 1,000-1,500 m down from the summit. They were also reported in Kali Batang and Beha Barat during 4-14 December, usually moving 800-1,000 m downslope. Between 5 and 14 December, gray and white plumes from Second Crater reached 300 m multiple times. During 12-15 December steam plumes rose 300-500 m above the Main crater. Activity decreased during 18-26 December but increased again during the last few days of the month. On 28 December, incandescent blocks were reported 1,500 m down Kali Pangi and Nanitu, and 1,750 m down Kali Sense.

Incandescent blocks were reported in Kali Sesepi during 4-6 January and in Kali Batang and Beha Barat during 4-8 and 12-15 January (figure 44); they often traveled 800-1,200 m downslope. Activity tapered off in those drainages and incandescent blocks were last reported in Kali Beha Barat on 15 January traveling 800 m from the summit. Incandescent blocks were also reported traveling usually 1,000-1,500 m down the Nanitu, Sense, and Pangi drainages during 4-19 January. Blocks continued to occasionally descend up to 1,000 m down Kali Nanitu through 24 January. Pulses of activity occurred at the summit of Second Crater a few times in January. Steam plumes rose 25-50 m during 8-9 January and again during 16-31 January, with plumes rising 300-400 m on 20, 29, and 31 January. Incandescence was noted 10-25 m above the summit of Second Crater during 27-30 January.

Figure (see Caption) Figure 44. Incandescent material descends the Beha Barat, Sense, Nanitu, and Pangi drainages on the NW flank of Karangetang in early January 2020. Courtesy of Bobyson Lamanepa; posted on Twitter on 6 January 2020.

Activity diminished significantly after mid-January 2020. Steam plumes at the Main Crater rose 50-100 m on the few days where the summit was not obscured by fog during February. Faint incandescence occurred at the Main Crater on 7 February, and steam plumes rising 25-50 m from Second Crater that day were the only events reported there in February. During March, steam plumes persisted from the Main Crater, with heights of over 100 m during short periods from 8-16 March and 25-30 March. Weak incandescence was reported from the Main Crater only once, on 25 March. Very little activity occurred at Second Crater during March, with only steam plumes reported rising 25-300 m from the 22nd to the 28th (figure 45).

Figure (see Caption) Figure 45. Steam plumes at Karangetang rose over 100 m above both summit craters multiple times during March, including on 26 March 2020. Courtesy of PVMBG and Oystein Anderson.

The Darwin VAAC reported a continuous ash emission on 4 April 2020 that rose to 2.1 km altitude and drifted SW for a few hours before dissipating. Incandescence visible 25 m above both craters on 13 April was the only April activity reported by PVMBG other than steam plumes from the Main Crater that rose 50-500 m on most days. Steam plumes of 50-100 m were reported from Second Crater during 11-13 April. Activity remained sporadic throughout May 2020. Steam plumes from the Main Crater rose 50-300 m each day. Satellite imagery identified steam plumes and incandescence from both summit craters on 3 May (figure 46). Faint incandescence was observed at the Main Crater on 12 and 27 May. Steam plumes rose 25-50 m from Second Crater on a few days; a 200-m-high plume was reported on 27 May. Bluish emissions were observed on the S and SW flanks on 28 May.

Figure (see Caption) Figure 46. Dense steam plumes and thermal anomalies were present at both summit craters of Karangetang on 3 May 2020. Sentinel 2 satellite image with Natural Color (bands 4, 3, 2) (left) and Atmospheric Penetration rendering (bands 12, 11, 8a) (right); courtesy of Sentinel Hub Playground.

Geologic Background. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi island. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Øystein Lund Andersen (Twitter: @OysteinLAnderse, https://twitter.com/OysteinLAnderse, URL: http://www.oysteinlundandersen.com); Bobyson Lamanepa, Yogyakarta, Indonesia, (URL: https://twitter.com/BobyLamanepa/status/1214165637028728832).


Masaya (Nicaragua) — June 2020 Citation iconCite this Report

Masaya

Nicaragua

11.985°N, 86.165°W; summit elev. 594 m

All times are local (unless otherwise noted)


Lava lake level drops but remains active through May 2020; weak gas plumes

Masaya, which is about 20 km NW of the Nicaragua’s capital of Managua, is one of the most active volcanoes in that country and has a caldera that contains a number of craters (BGVN 43:11). The Santiago crater is the one most currently active and it contains a small lava lake that emits weak gas plumes (figure 85). This report summarizes activity during February through May 2020 and is based on Instituto Nicaragüense de Estudios Territoriales (INETER) monthly reports and satellite data. During the reporting period, the volcano was relatively calm, with only weak gas plumes.

Figure (see Caption) Figure 85. Satellite images of Masaya from Sentinel-2 on 18 April 2020, showing and a small gas plume drifting SW (top, natural color bands 4, 3, 2) and the lava lake (bottom, false color bands 12, 11, 4). Courtesy of Sentinel Hub Playground.

According to INETER, thermal images of the lava lake and temperature data in the fumaroles were taken using an Omega infrared gun and a forward-looking infrared (FLIR) SC620 thermal camera. The temperatures above the lava lake have decreased since November 2019, when the temperature was 287°C, dropping to 96°C when measured on 14 May 2020. INETER attributed this decrease to subsidence in the level of the lava lake by 5 m which obstructed part of the lake and concentrated the gas emissions in the weak plume. Convection continued in the lava lake, which in May had decreased to a diameter of 3 m. Many landslides had occurred in the E, NE, and S walls of the crater rim due to rock fracturing caused by the high heat and acidity of the emissions.

During the reporting period, the MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system recorded numerous thermal anomalies from the lava lake based on MODIS data (figure 86). Infrared satellite images from Sentinel-2 regularly showed a strong signature from the lava lake through 18 May, after which the volcano was covered by clouds.

Figure (see Caption) Figure 86. Thermal anomalies at Masaya during February through May 2020. The larger anomalies with black lines are more distant and not related to the volcano. Courtesy of MIROVA.

Measurements of sulfur dioxide (SO2) made by INETER in the section of the Ticuantepe - La Concepción highway (just W of the volcano) with a mobile DOAS system varied between a low of just over 1,000 metric tons/day in mid-November 2019 to a high of almost 2,500 tons/day in late May. Temperatures of fumaroles in the Cerro El Comalito area, just ENE of Santiago crater, ranged from 58 to 76°C during February-May 2020, with most values in the 69-72°C range.

Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras caldera and is itself a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The Nindirí and Masaya cones, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6,500 years ago. Historical lava flows cover much of the caldera floor and there is a lake at the far eastern end. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals have caused health hazards and crop damage.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Shishaldin (United States) — June 2020 Citation iconCite this Report

Shishaldin

United States

54.756°N, 163.97°W; summit elev. 2857 m

All times are local (unless otherwise noted)


Intermittent thermal activity and a possible new cone at the summit crater during February-May 2020

Shishaldin is located near the center of Unimak Island in Alaska, with the current eruption phase beginning in July 2019 and characterized by ash plumes, lava flows, lava fountaining, pyroclastic flows, and lahars. More recently, in late 2019 and into January 2020, activity consisted of multiple lava flows, pyroclastic flows, lahars, and ashfall events (BGVN 45:02). This report summarizes activity from February through May 2020, including gas-and-steam emissions, brief thermal activity in mid-March, and a possible new cone within the summit crater. The primary source of information comes from the Alaska Volcano Observatory (AVO) reports and various satellite data.

Volcanism during February 2020 was relatively low, consisting of weakly to moderately elevated surface temperatures during 1-4 February and occasional small gas-and-steam plumes (figure 37). By 6 February both seismicity and surface temperatures had decreased. Seismicity and surface temperatures increased slightly again on 8 March and remained elevated through the rest of the reporting period. Intermittent gas-and-steam emissions were also visible from mid-March (figure 38) through May. Minor ash deposits visible on the upper SE flank may have been due to ash resuspension or a small collapse event at the summit, according to AVO.

Figure (see Caption) Figure 37. Photo of a gas-and-steam plume rising from the summit crater at Shishaldin on 22 February 2020. Photo courtesy of Ben David Jacob via AVO.
Figure (see Caption) Figure 38. A Worldview-2 panchromatic satellite image on 11 March 2020 showing a gas-and-steam plume rising from the summit of Shishaldin and minor ash deposits on the SE flank (left). Aerial photo showing minor gas-and-steam emissions rising from the summit crater on 11 March (right). Some erosion of the snow and ice on the upper flanks is a result of the lava flows from the activity in late 2019 and early 2020. Photo courtesy of Matt Loewen (left) and Ed Fischer (right) via AVO.

On 14 March, lava and a possible new cone were visible in the summit crater using satellite imagery, accompanied by small explosion signals. Strong thermal signatures due to the lava were also seen in Sentinel-2 satellite data and continued strongly through the month (figure 39). The lava reported by AVO in the summit crater was also reflected in satellite-based MODIS thermal anomalies recorded by the MIROVA system (figure 40). Seismic and infrasound data identified small explosions signals within the summit crater during 14-19 March.

Figure (see Caption) Figure 39. Sentinel-2 thermal satellite images (bands 12, 11, 8A) show a bright hotspot (yellow-orange) at the summit crater of Shishaldin during mid-March 2020 that decreases in intensity by late March. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 40. MIROVA thermal data showing a brief increase in thermal anomalies during late March 2020 and on two days in late April between periods of little to no activity. Courtesy of MIROVA.

AVO released a Volcano Observatory Notice for Aviation (VONA) stating that seismicity had decreased by 16 April and that satellite data no longer showed lava or additional changes in the crater since the start of April. Sentinel-2 thermal satellite imagery continued to show a weak hotspot in the crater summit through May (figure 41), which was also detected by the MIROVA system on two days. A daily report on 6 May reported a visible ash deposit extending a short distance SE from the summit, which had likely been present since 29 April. AVO noted that the timing of the deposit corresponds to an increase in the summit crater diameter and depth, further supporting a possible small collapse. Small gas-and-steam emissions continued intermittently and were accompanied by weak tremors and occasional low-frequency earthquakes through May (figure 42). Minor amounts of sulfur dioxide were detected in the gas-and-steam emissions during 20 and 29 April, and 2, 16, and 28 May.

Figure (see Caption) Figure 41. Sentinel-2 thermal satellite images (bands 12, 11, 8A) show occasional gas-and-steam emissions rising from Shishaldin on 26 February (top left) and 24 April 2020 (bottom left) and a weak hotspot (yellow-orange) persisting at the summit crater during April and early May 2020. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 42. A Worldview-1 panchromatic satellite image showing gas-and-steam emissions rising from the summit of Shishaldin on 1 May 2020 (local time) (left). Aerial photo of the N flank of Shishaldin with minor gas-and-steam emissions rising from the summit on 8 May (right). Photo courtesy of Matt Loewen (left) and Levi Musselwhite (right) via AVO.

Geologic Background. The beautifully symmetrical Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steam plume often rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the W and NE sides at 1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Krakatau (Indonesia) — June 2020 Citation iconCite this Report

Krakatau

Indonesia

6.102°S, 105.423°E; summit elev. 155 m

All times are local (unless otherwise noted)


Strombolian explosions, ash plumes, and crater incandescence during April 2020

Krakatau, located in the Sunda Strait between Indonesia’s Java and Sumatra Islands, experienced a major caldera collapse around 535 CE, forming a 7-km-wide caldera ringed by three islands. On 22 December 2018, a large explosion and flank collapse destroyed most of the 338-m-high island of Anak Krakatau (Child of Krakatau) and generated a deadly tsunami (BGVN 44:03). The near-sea level crater lake inside the remnant of Anak Krakatau was the site of numerous small steam and tephra explosions. A larger explosion in December 2019 produced the beginnings of a new cone above the surface of crater lake (BGVN 45:02). Recently, volcanism has been characterized by occasional Strombolian explosions, dense ash plumes, and crater incandescence. This report covers activity from February through May 2020 using information provided by the Indonesian Center for Volcanology and Geological Hazard Mitigation, also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), the Darwin Volcanic Ash Advisory Center (VAAC), and various satellite data.

Activity during February 2020 consisted of dominantly white gas-and-steam emissions rising 300 m above the crater, according to PVMBG. According to the Darwin VAAC, a ground observer reported an eruption on 7 and 8 February, but no volcanic ash was observed. During 10-11 February, a short-lived eruption was detected by seismograms which produced an ash plume up to 1 km above the crater drifting E. MAGMA Indonesia reported two eruptions on 18 March, both of which rose to 300 m above the crater. White gas-and-steam emissions were observed for the rest of the month and early April.

On 10 April PVMBG reported two eruptions, at 2158 and 2235, both of which produced dark ash plumes rising 2 km above the crater followed by Strombolian explosions ejecting incandescent material that landed on the crater floor (figures 108 and 109). The Darwin VAAC issued a notice at 0145 on 11 April reporting an ash plume to 14.3 km altitude drifting WNW, however this was noted with low confidence due to the possible mixing of clouds. During the same day, an intense thermal hotspot was detected in the HIMAWARI thermal satellite imagery and the NASA Global Sulfur Dioxide page showed a strong SO2 plume at 11.3 km altitude drifting W (figure 110). The CCTV Lava93 webcam showed new lava flows and lava fountaining from the 10-11 April eruptions. This activity was evident in the MIROVA (Middle InfraRed Observation of Volcanic Activity) graph of MODIS thermal anomaly data (figure 111).

Figure (see Caption) Figure 108. Webcam (Lava93) images of Krakatau on 10 April 2020 showing Strombolian explosions, strong incandescence, and ash plumes rising from the crater. Courtesy of PVMBG and MAGMA Indonesia.
Figure (see Caption) Figure 109. Webcam image of incandescent Strombolian explosions at Krakatau on 10 April 2020. Courtesy of PVMBG and MAGMA Indonesia.
Figure (see Caption) Figure 110. Strong sulfur dioxide emissions rising from Krakatau and drifting W were detected using the TROPOMI instrument on the Sentinel-5P satellite on 11 April 2020 (top row). Smaller volumes of SO2 were visible in Sentinel-5P/TROPOMI maps on 13 (bottom left) and 19 April (bottom right). Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 111. Thermal activity at Anak Krakatau from 29 June-May 2020 shown on a MIROVA Log Radiative Power graph. The power and frequency of the thermal anomalies sharply increased in mid-April. After the larger eruptive event in mid-April the thermal anomalies declined slightly in strength but continued to be detected intermittently through May. Courtesy of MIROVA.

Strombolian activity rising up to 500 m continued into 12 April and was accompanied by SO2 emissions that rose 3 km altitude, drifting NW according to a VAAC notice. PVMBG reported an eruption on 13 April at 2054 that resulted in incandescence as high as 25 m above the crater. Volcanic ash, accompanied by white gas-and-steam emissions, continued intermittently through 18 April, many of which were observed by the CCTV webcam. After 18 April only gas-and-steam plumes were reported, rising up to 100 m above the crater; Sentinel-2 satellite imagery showed faint thermal anomalies in the crater (figure 112). SO2 emissions continued intermittently throughout April, though at lower volumes and altitudes compared to the 11th. MODIS satellite data seen in MIROVA showed intermittent thermal anomalies through May.

Figure (see Caption) Figure 112. Sentinel-2 thermal satellite images showing the cool crater lake on 20 March (top left) followed by minor heating of the crater during April and May 2020. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

Geologic Background. The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Taal (Philippines) — June 2020 Citation iconCite this Report

Taal

Philippines

14.002°N, 120.993°E; summit elev. 311 m

All times are local (unless otherwise noted)


Eruption on 12 January with explosions through 22 January; steam plumes continuing into March

Taal volcano is in a caldera system located in southern Luzon island and is one of the most active volcanoes in the Philippines. It has produced around 35 recorded eruptions since 3,580 BCE, ranging from VEI 1 to 6, with the majority of eruptions being a VEI 2. The caldera contains a lake with an island that also contains a lake within the Main Crater (figure 12). Prior to 2020 the most recent eruption was in 1977, on the south flank near Mt. Tambaro. The United Nations Office for the Coordination of Humanitarian Affairs in the Philippines reports that over 450,000 people live within 40 km of the caldera (figure 13). This report covers activity during January through February 2020 including the 12 to 22 January eruption, and is based on reports by Philippine Institute of Volcanology and Seismology (PHIVOLCS), satellite data, geophysical data, and media reports.

Figure (see Caption) Figure 12. Annotated satellite images showing the Taal caldera, Volcano Island in the caldera lake, and features on the island including Main Crater. Imagery courtesy of Planet Inc.
Figure (see Caption) Figure 13. Map showing population totals within 14 and 17 km of Volcano Island at Taal. Courtesy of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA).

The hazard status at Taal was raised to Alert Level 1 (abnormal, on a scale of 0-5) on 28 March 2019. From that date through to 1 December there were 4,857 earthquakes registered, with some felt nearby. Inflation was detected during 21-29 November and an increase in CO2 emission within the Main Crater was observed. Seismicity increased beginning at 1100 on 12 January. At 1300 there were phreatic (steam) explosions from several points inside Main Crater and the Alert Level was raised to 2 (increasing unrest). Booming sounds were heard in Talisay, Batangas, at 1400; by 1402 the plume had reached 1 km above the crater, after which the Alert Level was raised to 3 (magmatic unrest).

Phreatic eruption on 12 January 2020. A seismic swarm began at 1100 on 12 January 2020 followed by a phreatic eruption at 1300. The initial activity consisted of steaming from at least five vents in Main Crater and phreatic explosions that generated 100-m-high plumes. PHIVOLCS raised the Alert Level to 2. The Earth Observatory of Singapore reported that the International Data Center (IDC) for the Comprehensive test Ban Treaty (CTBT) in Vienna noted initial infrasound detections at 1450 that day.

Booming sounds were heard at 1400 in Talisay, Batangas (4 km NNE from the Main Crater), and at 1404 volcanic tremor and earthquakes felt locally were accompanied by an eruption plume that rose 1 km; ash fell to the SSW. The Alert Level was raised to 3 and the evacuation of high-risk barangays was recommended. Activity again intensified around 1730, prompting PHIVOLCS to raise the Alert Level to 4 and recommend a total evacuation of the island and high-risk areas within a 14-km radius. The eruption plume of steam, gas, and tephra significantly intensified, rising to 10-15 km altitude and producing frequent lightning (figures 14 and 15). Wet ash fell as far away as Quezon City (75 km N). According to news articles schools and government offices were ordered to close and the Ninoy Aquino International Airport (56 km N) in Manila suspended flights. About 6,000 people had been evacuated. Residents described heavy ashfall, low visibility, and fallen trees.

Figure (see Caption) Figure 14. Lightning produced during the eruption of Taal during 1500 on 12 January to 0500 on 13 January 2020 local time (0700-2100 UTC on 12 January). Courtesy of Chris Vagasky, Vaisala.
Figure (see Caption) Figure 15. Lightning strokes produced during the first days of the Taal January 2020 eruption. Courtesy of Domcar C Lagto/SIPA/REX/Shutterstock via The Guardian.

In a statement issued at 0320 on 13 January, PHIVOLCS noted that ashfall had been reported across a broad area to the north in Tanauan (18 km NE), Batangas; Escala (11 km NW), Tagaytay; Sta. Rosa (32 km NNW), Laguna; Dasmariñas (32 km N), Bacoor (44 km N), and Silang (22 km N), Cavite; Malolos (93 km N), San Jose Del Monte (87 km N), and Meycauayan (80 km N), Bulacan; Antipolo (68 km NNE), Rizal; Muntinlupa (43 km N), Las Piñas (47 km N), Marikina (70 km NNE), Parañaque (51 km N), Pasig (62 km NNE), Quezon City, Mandaluyong (62 km N), San Juan (64 km N), Manila; Makati City (59 km N) and Taguig City (55 km N). Lapilli (2-64 mm in diameter) fell in Tanauan and Talisay; Tagaytay City (12 km N); Nuvali (25 km NNE) and Sta (figure 16). Rosa, Laguna. Felt earthquakes (Intensities II-V) continued to be recorded in local areas.

Figure (see Caption) Figure 16. Ashfall from the Taal January 2020 eruption in Lemery (top) and in the Batangas province (bottom). Photos posted on 13 January, courtesy of Ezra Acayan/Getty Images, Aaron Favila/AP, and Ted Aljibe/AFP via Getty Images via The Guardian.

Magmatic eruption on 13 January 2020. A magmatic eruption began during 0249-0428 on 13 January, characterized by weak lava fountaining accompanied by thunder and flashes of lightning. Activity briefly waned then resumed with sporadic weak fountaining and explosions that generated 2-km-high, dark gray, steam-laden ash plumes (figure 17). New lateral vents opened on the N flank, producing 500-m-tall lava fountains. Heavy ashfall impacted areas to the SW, including in Cuenca (15 km SSW), Lemery (16 km SW), Talisay, and Taal (15 km SSW), Batangas (figure 18).

Figure (see Caption) Figure 17. Ash plumes seen from various points around Taal in the initial days of the January 2020 eruption, posted on 13 January. Courtesy of Eloisa Lopez/Reuters, Kester Ragaza/Pacific Press/Shutterstock, Ted Aljibe/AFP via Getty Images, via The Guardian.
Figure (see Caption) Figure 18. Map indicating areas impacted by ashfall from the 12 January eruption through to 0800 on the 13th. Small yellow circles (to the N) are ashfall report locations; blue circles (at the island and to the S) are heavy ashfall; large green circles are lapilli (particles measuring 2-64 mm in diameter). Modified from a map courtesy of Lauriane Chardot, Earth Observatory of Singapore; data taken from PHIVOLCS.

News articles noted that more than 300 domestic and 230 international flights were cancelled as the Manila Ninoy Aquino International Airport was closed during 12-13 January. Some roads from Talisay to Lemery and Agoncillo were impassible and electricity and water services were intermittent. Ashfall in several provinces caused power outages. Authorities continued to evacuate high-risk areas, and by 13 January more than 24,500 people had moved to 75 shelters out of a total number of 460,000 people within 14 km.

A PHIVOLCS report for 0800 on the 13th through 0800 on 14 January noted that lava fountaining had continued, with steam-rich ash plumes reaching around 2 km above the volcano and dispersing ash SE and W of Main Crater. Volcanic lighting continued at the base of the plumes. Fissures on the N flank produced 500-m-tall lava fountains. Heavy ashfall continued in the Lemery, Talisay, Taal, and Cuenca, Batangas Municipalities. By 1300 on the 13th lava fountaining generated 800-m-tall, dark gray, steam-laden ash plumes that drifted SW. Sulfur dioxide emissions averaged 5,299 metric tons/day (t/d) on 13 January and dispersed NNE (figure 19).

Figure (see Caption) Figure 19. Compilation of sulfur dioxide plumes from TROPOMI overlaid in Google Earth for 13 January from 0313-1641 UT. Courtesy of NASA Global Sulfur Dioxide Monitoring Page and Google Earth.

Explosions and ash emission through 22 January 2020. At 0800 on 15 January PHIVOLCS stated that activity was generally weaker; dark gray, steam-laden ash plumes rose about 1 km and drifted SW. Satellite images showed that the Main Crater lake was gone and new craters had formed inside Main Crater and on the N side of Volcano Island.

PHIVOLCS reported that activity during 15-16 January was characterized by dark gray, steam-laden plumes that rose as high as 1 km above the vents in Main Crater and drifted S and SW. Sulfur dioxide emissions were 4,186 t/d on 15 January. Eruptive events at 0617 and 0621 on 16 January generated short-lived, dark gray ash plumes that rose 500 and 800 m, respectively, and drifted SW. Weak steam plumes rose 800 m and drifted SW during 1100-1700, and nine weak explosions were recorded by the seismic network.

Steady steam emissions were visible during 17-21 January. Infrequent weak explosions generated ash plumes that rose as high as 1 km and drifted SW. Sulfur dioxide emissions fluctuated and were as high as 4,353 t/d on 20 January and as low as 344 t/d on 21 January. PHIVOLCS reported that white steam-laden plumes rose as high as 800 m above main vent during 22-28 January and drifted SW and NE; ash emissions ceased around 0500 on 22 January. Remobilized ash drifted SW on 22 January due to strong low winds, affecting the towns of Lemery (16 km SW) and Agoncillo, and rose as high as 5.8 km altitude as reported by pilots. Sulfur dioxide emissions were low at 140 t/d.

Steam plumes through mid-April 2020. The Alert Level was lowered to 3 on 26 January and PHIVOLCS recommended no entry onto Volcano Island and Taal Lake, nor into towns on the western side of the island within a 7-km radius. PHIVOLCS reported that whitish steam plumes rose as high as 800 m during 29 January-4 February and drifted SW (figure 20). The observed steam plumes rose as high as 300 m during 5-11 February and drifted SW.

Sulfur dioxide emissions averaged around 250 t/d during 22-26 January; emissions were 87 t/d on 27 January and below detectable limits the next day. During 29 January-4 February sulfur dioxide emissions ranged to a high of 231 t/d (on 3 February). The following week sulfur dioxide emissions ranged from values below detectable limits to a high of 116 t/d (on 8 February).

Figure (see Caption) Figure 20. Taal Volcano Island producing gas-and-steam plumes on 15-16 January 2020. Courtesy of James Reynolds, Earth Uncut.

On 14 February PHIVOLCS lowered the Alert Level to 2, noting a decline in the number of volcanic earthquakes, stabilizing ground deformation of the caldera and Volcano Island, and diffuse steam-and-gas emission that continued to rise no higher than 300 m above the main vent during the past three weeks. During 14-18 February sulfur dioxide emissions ranged from values below detectable limits to a high of 58 tonnes per day (on 16 February). Sulfur dioxide emissions were below detectable limits during 19-20 February. During 26 February-2 March steam plumes rose 50-300 m above the vent and drifted SW and NE. PHIVOLCS reported that during 4-10 March weak steam plumes rose 50-100 m and drifted SW and NE; moderate steam plumes rose 300-500 m and drifted SW during 8-9 March. During 11-17 March weak steam plumes again rose only 50-100 m and drifted SW and NE.

PHIVOLCS lowered the Alert Level to 1 on 19 March and recommended no entry onto Volcano Island, the area defined as the Permanent Danger Zone. During 8-9 April steam plumes rose 100-300 m and drifted SW. As of 1-2 May 2020 only weak steaming and fumarolic activity from fissure vents along the Daang Kastila trail was observed.

Evacuations. According to the Disaster Response Operations Monitoring and Information Center (DROMIC) there were a total of 53,832 people dispersed to 244 evacuation centers by 1800 on 15 January. By 21 January there were 148,987 people in 493 evacuation. The number of residents in evacuation centers dropped over the next week to 125,178 people in 497 locations on 28 January. However, many residents remained displaced as of 3 February, with DROMIC reporting 23,915 people in 152 evacuation centers, but an additional 224,188 people staying at other locations.

By 10 February there were 17,088 people in 110 evacuation centers, and an additional 211,729 staying at other locations. According to the DROMIC there were a total of 5,321 people in 21 evacuation centers, and an additional 195,987 people were staying at other locations as of 19 February.

The number of displaced residents continued to drop, and by 3 March there were 4,314 people in 12 evacuation centers, and an additional 132,931 people at other locations. As of 11 March there were still 4,131 people in 11 evacuation centers, but only 17,563 staying at other locations.

Deformation and ground cracks. New ground cracks were observed on 13 January in Sinisian (18 km SW), Mahabang Dahilig (14 km SW), Dayapan (15 km SW), Palanas (17 km SW), Sangalang (17 km SW), and Poblacion (19 km SW) Lemery; Pansipit (11 km SW), Agoncillo; Poblacion 1, Poblacion 2, Poblacion 3, Poblacion 5 (all around 17 km SW), Talisay, and Poblacion (11 km SW), San Nicolas (figure 21). A fissure opened across the road connecting Agoncillo to Laurel, Batangas. New ground cracking was reported the next day in Sambal Ibaba (17 km SW), and portions of the Pansipit River (SW) had dried up.

Figure (see Caption) Figure 21. Video screenshots showing ground cracks that formed during the Taal unrest and captured on 15 and 16 January 2020. Courtesy of James Reynolds, Earth Uncut.

Dropping water levels of Taal Lake were first observed in some areas on 16 January but reported to be lake-wide the next day. The known ground cracks in the barangays of Lemery, Agoncillo, Talisay, and San Nicolas in Batangas Province widened a few centimeters by 17 January, and a new steaming fissure was identified on the N flank of the island.

GPS data had recorded a sudden widening of the caldera by ~1 m, uplift of the NW sector by ~20 cm, and subsidence of the SW part of Volcano Island by ~1 m just after the main eruption phase. The rate of deformation was smaller during 15-22 January, and generally corroborated by field observations; Taal Lake had receded about 30 cm by 25 January but about 2.5 m of the change (due to uplift) was observed around the SW portion of the lake, near the Pansipit River Valley where ground cracking had been reported.

Weak steaming (plumes 10-20 m high) from ground cracks was visible during 5-11 February along the Daang Kastila trail which connects the N part of Volcano Island to the N part of the main crater. PHIVOLCS reported that during 19-24 February steam plumes rose 50-100 m above the vent and drifted SW. Weak steaming (plumes up to 20 m high) from ground cracks was visible during 8-14 April along the Daang Kastila trail which connects the N part of Volcano Island to the N part of the main crater.

Seismicity. Between 1300 on 12 January and 0800 on 21 January the Philippine Seismic Network (PSN) had recorded a total of 718 volcanic earthquakes; 176 of those had magnitudes ranging from 1.2-4.1 and were felt with Intensities of I-V. During 20-21 January there were five volcanic earthquakes with magnitudes of 1.6-2.5; the Taal Volcano network (which can detect smaller events not detectable by the PSN) recorded 448 volcanic earthquakes, including 17 low-frequency events. PHIVOLCS stated that by 21 January hybrid earthquakes had ceased and both the number and magnitude of low-frequency events had diminished.

Geologic Background. Taal is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. Though not topographically prominent, its prehistorical eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions have caused many fatalities.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Disaster Response Operations Monitoring and Information Center (DROMIC) (URL: https://dromic.dswd.gov.ph/); United Nations Office for the Coordination of Humanitarian Affairs, Philippines (URL: https://www.unocha.org/philippines); James Reynolds, Earth Uncut TV (Twitter: @EarthUncutTV, URL: https://www.earthuncut.tv/, YouTube: https://www.youtube.com/user/TyphoonHunter); Chris Vagasky, Vaisala Inc., Louisville, Colorado, USA (URL: https://www.vaisala.com/en?type=1, Twitter: @COweatherman, URL: https://twitter.com/COweatherman); Earth Observatory of Singapore, Nanyang Technological University, 50 Nanyang Avenue, Singapore (URL: https://www.earthobservatory.sg/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Relief Web, Flash Update No. 1 - Philippines: Taal Volcano eruption (As of 13 January 2020, 2 p.m. local time) (URL: https://reliefweb.int/report/philippines/flash-update-no-1-philippines-taal-volcano-eruption-13-january-2020-2-pm-local); Bloomberg, Philippines Braces for Hazardous Volcano Eruption (URL: https://www.bloomberg.com/news/articles/2020-01-12/philippines-raises-alert-level-in-taal-as-volcano-spews-ash); National Public Radio (NPR), Volcanic Eruption In Philippines Causes Thousands To Flee (URL: npr.org/2020/01/13/795815351/volcanic-eruption-in-philippines-causes-thousands-to-flee); Reuters (http://www.reuters.com/); Agence France-Presse (URL: http://www.afp.com/); Pacific Press (URL: http://www.pacificpress.com/); Shutterstock (URL: https://www.shutterstock.com/); Getty Images (URL: http://www.gettyimages.com/); Google Earth (URL: https://www.google.com/earth/).


Unnamed (Tonga) — March 2020 Citation iconCite this Report

Unnamed

Tonga

18.325°S, 174.365°W; summit elev. -40 m

All times are local (unless otherwise noted)


Additional details and pumice raft drift maps from the August 2019 submarine eruption

In the northern Tonga region, approximately 80 km NW of Vava’u, large areas of floating pumice, termed rafts, were observed starting as early as 7 August 2019. The area of these andesitic pumice rafts was initially 195 km2 with the layers measuring 15-30 cm thick and were produced 200 m below sea level (Jutzeler et al. 2020). The previous report (BGVN 44:11) described the morphology of the clasts and the rafts, and their general westward path from 9 August to 9 October 2019, with the first sighting occurring on 9 August NW of Vava’u in Tonga. This report updates details regarding the submarine pumice raft eruption in early August 2019 using new observations and data from Brandl et al. (2019) and Jutzeler et al. (2020).

The NoToVE-2004 (Northern Tonga Vents Expedition) research cruise on the RV Southern Surveyor (SS11/2004) from the Australian CSIRO Marine National Facility traveled to the northern Tonga Arc and discovered several submarine basalt-to-rhyolite volcanic centers (Arculus, 2004). One of these volcanic centers 50 km NW of Vava’u was the unnamed seamount (volcano number 243091) that had erupted in 2001 and again in 2019, unofficially designated “Volcano F” for reference purposes by Arculus (2004) and also used by Brandl et al. (2019). It is a volcanic complex that rises more than 1 km from the seafloor with a central 6 x 8.7 km caldera and a volcanic apron measuring over 50 km in diameter (figures 19 and 20). Arculus (2004) described some of the dredged material as “fresh, black, plagioclase-bearing lava with well-formed, glassy crusts up to 2cm thick” from cones by the eastern wall of the caldera; a number of apparent flows, lava or debris, were observed draping over the northern wall of the caldera.

Figure (see Caption) Figure 19. Visualization of the unnamed submarine Tongan volcano (marked “Volcano F”) using bathymetric data to show the site of the 6-8 August 2020 eruption and the rest of the cone complex. Courtesy of Philipp Brandl via GEOMAR.
Figure (see Caption) Figure 20. Map of the unnamed submarine Tongan volcano using satellite imagery, bathymetric data, with shading from the NW. The yellow circle indicates the location of the August 2019 activity. Young volcanic cones are marked “C” and those with pit craters at the top are marked with “P.” Courtesy of Brandl et al. (2019).

The International Seismological Centre (ISC) Preliminary Bulletin listed a particularly strong (5.7 Mw) earthquake at 2201 local time on 5 August, 15 km SSW of the volcano at a depth of 10 km (Brandl et al. 2019). This event was followed by six slightly lower magnitude earthquakes over the next two days.

Sentinel-2 satellite imagery showed two concentric rings originating from a point source (18.307°S 174.395°W) on 6 August (figure 21), which could be interpreted as small weak submarine plumes or possibly a series of small volcanic cones, according to Brandl et al. (2019). The larger ring is about 1.2 km in diameter and the smaller one measures 250 m. By 8 August volcanic activity had decreased, but the pumice rafts that were produced remained visible through at least early October (BGVN 44:11). Brandl et al. (2019) states that, due to the lack of continued observed activity rising from this location, the eruption was likely a 2-day-long event during 6-8 August.

Figure (see Caption) Figure 21. Sentinel-2 satellite image of possible gas/vapor emissions (streaks) on 6 August 2019 drifting NW, which is the interpreted site for the unnamed Tongan seamount. The larger ring is about 1.2 km in diameter and the smaller one measures 250 m. Image using False Color (urban) rendering (bands 12, 11, 4); courtesy of Sentinel Hub Playground.

The pumice was first observed on 9 August occurred up to 56 km from the point of origin, according to Jutzeler et al. (2020). By calculating the velocity (14 km/day) of the raft using three satellites, Jutzeler et al. (2020) determined the pumice was erupted immediately after the satellite image of the submarine plumes on 6 August (UTC time). Minor activity at the vent may have continued on 8 and 11 August (UTC time) with pale blue-green water discoloration (figure 22) and a small (less than 1 km2) diffuse pumice raft 2-5 km from the vent.

Figure (see Caption) Figure 22. Sentinel-2 satellite image of the last visible activity occurring W of the unnamed submarine Tongan volcano on 8 August 2019, represented by slightly discolored blue-green water. Image using Natural Color rendering (bands 4, 3, 2) and enhanced with color correction; courtesy of Sentinel Hub Playground.

Continuous observations using various satellite data and observations aboard the catamaran ROAM tracked the movement and extent of the pumice raft that was produced during the submarine eruption in early August (figure 23). The first visible pumice raft was observed on 8 August 2019, covering more than 136.7 km2 between the volcanic islands of Fonualei and Late and drifting W for 60 km until 9 August (Brandl et al. 2019; Jutzeler 2020). The next day, the raft increased to 167.2-195 km2 while drifting SW for 74 km until 14 August. Over the next three days (10-12 August) the size of the raft briefly decreased in size to less than 100 km2 before increasing again to 157.4 km2 on 14 August; at least nine individual rafts were mapped and identified on satellite imagery (Brandl et al. 2019). On 15 August sailing vessels observed a large pumice raft about 75 km W of Late Island (see details in BGVN 44:11), which was the same one as seen in satellite imagery on 8 August.

Figure (see Caption) Figure 23. Map of the extent of discolored water and the pumice raft from the unnamed submarine Tongan volcano between 8 and 14 August 2019 using imagery from NASA’s MODIS, ESA’s Sentinel-2 satellite, and observations from aboard the catamaran ROAM (BGVN 44:11). Back-tracing the path of the pumice raft points to a source location at the unnamed submarine Tongan volcano. Courtesy of Brandl et al. (2019).

By 17 August high-resolution satellite images showed an area of large and small rafts measuring 222 km2 and were found within a field of smaller rafts for a total extent of 1,350 km2, which drifted 73 km NNW through 22 August before moving counterclockwise for three days (figure f; Jutzeler et al., 2020). Small pumice ribbons encountered the Oneata Lagoon on 30 August, the first island that the raft came into contact (Jutzeler et al. 2020). By 2 September, the main raft intersected with Lakeba Island (460 km from the source) (figure 24), breaking into smaller ribbons that started to drift W on 8 September. On 19 September the small rafts (less than 100 m x less than 2 km) entered the strait between Viti Levu and Vanua Levu, the two main islands of Fiji, while most of the others were stranded 60 km W in the Yasawa Islands for more than two months (Jutzeler et al., 2020).

Figure (see Caption) Figure 24. Time-series map of the raft dispersal from the unnamed submarine Tongan volcano using multiple satellite images. A) Map showing the first days of the raft dispersal starting on 7 August 2019 and drifting SW from the vent (marked with a red triangle). Precursory seismicity that began on 5 August is marked with a white star. By 15-17 August the raft was entrained in an ocean loop or eddy. The dashed lines represent the path of the sailing vessels. B) Map of the raft dispersal using high-resolution Sentinel-2 and -3 imagery. Two dispersal trails (red and blue dashed lines) show the daily dispersal of two parts of the raft that were separated on 17 August 2019. Courtesy of Jutzeler et al. (2020).

References: Arculus, R J, SS2004/11 shipboard scientists, 2004. SS11/2004 Voyage Summary: NoToVE-2004 (Northern Tonga Vents Expedition): submarine hydrothermal plume activity and petrology of the northern Tofua Arc, Tonga. https://www.cmar.csiro.au/data/reporting/get file.cfm?eovpub id=901.

Brandl P A, Schmid F, Augustin N, Grevemeyer I, Arculus R J, Devey C W, Petersen S, Stewart M , Kopp K, Hannington M D, 2019. The 6-8 Aug 2019 eruption of ‘Volcano F’ in the Tofua Arc, Tonga. Journal of Volcanology and Geothermal Research: https://doi.org/10.1016/j.jvolgeores.2019.106695

Jutzeler M, Marsh R, van Sebille E, Mittal T, Carey R, Fauria K, Manga M, McPhie J, 2020. Ongoing Dispersal of the 7 August 2019 Pumice Raft From the Tonga Arc in the Southwestern Pacific Ocean. AGU Geophysical Research Letters: https://doi.orh/10.1029/2019GL086768.

Geologic Background. A submarine volcano along the Tofua volcanic arc was first observed in September 2001. The newly discovered volcano lies NW of the island of Vava'u about 35 km S of Fonualei and 60 km NE of Late volcano. The site of the eruption is along a NNE-SSW-trending submarine plateau with an approximate bathymetric depth of 300 m. T-phase waves were recorded on 27-28 September 2001, and on the 27th local fishermen observed an ash-rich eruption column that rose above the sea surface. No eruptive activity was reported after the 28th, but water discoloration was documented during the following month. In early November rafts and strandings of dacitic pumice were reported along the coast of Kadavu and Viti Levu in the Fiji Islands. The depth of the summit of the submarine cone following the eruption determined to be 40 m during a 2007 survey; the crater of the 2001 eruption was breached to the E.

Information Contacts: Jan Steffen, Communication and Media, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany; Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Klyuchevskoy (Russia) — June 2020 Citation iconCite this Report

Klyuchevskoy

Russia

56.056°N, 160.642°E; summit elev. 4754 m

All times are local (unless otherwise noted)


Strombolian activity November 2019 through May 2020; lava flow down the SE flank in April

Klyuchevskoy is part of the Klyuchevskaya volcanic group in northern Kamchatka and is one of the most frequently active volcanoes of the region. Eruptions produce lava flows, ashfall, and lahars originating from summit and flank activity. This report summarizes activity during October 2019 through May 2020, and is based on reports by the Kamchatkan Volcanic Eruption Response Team (KVERT) and satellite data.

There were no activity reports from 1 to 22 October, but gas emissions were visible in satellite images. At 1020 on 24 October (2220 on 23 October UTC) KVERT noted that there was a small ash component in the ash plume from erosion of the conduit, with the plume reaching 130 km ENE. The Aviation Colour Code was raised from Green to Yellow, then to Orange the following day. An ash plume continued on the 25th to 5-7 km altitude and extending 15 km SE and 70 km SW and reached 30 km ESE on the 26th. Similar activity continued through to the end of the month.

Moderate gas emissions continued during 1-19 November, but the summit was obscured by clouds. Strong nighttime incandescence was visible at the crater during the 10-11 November and thermal anomalies were detected on 8 and 10-13 November. Explosions produced ash plumes up to 6 km altitude on the 20-21st and Strombolian activity was reported during 20-22 November. Degassing continued from 23 November through 12 December, and a thermal anomaly was visible on the days when the summit was not covered by clouds. An ash plume was reported moving to the NW on the 13th, and degassing with a thermal anomaly and intermittent Strombolian activity then resumed, continuing through to the end of December with an ash plume reported on the 30th.

Gas-and-steam plumes continued into January 2020 with incandescence noted when the summit was clear (figure 33). Strombolian activity was reported again starting on the 3rd. A weak ash plume produced on the 6th extended 55 km E, and on the 21st an ash plume reached 5-5.5 km altitude and extended 190 km NE (figure 34). Another ash plume the next day rose to the same altitude and extended 388 km NE. During 23-29 Strombolian activity continued, and Vulcanian activity produced ash plumes up to 5.5 altitude, extending to 282 km E on the 30th, and 145 km E on the 31st.

Figure (see Caption) Figure 33. Incandescence and degassing were visible at Klyuchevskoy through January 2020, seen here on the 11th. Courtesy of KVERT.
Figure (see Caption) Figure 34. A low ash plume at Klyuchevskoy on 21 January 2020 extended 190 km NE. Courtesy of KVERT.

Strombolian activity continued throughout February with occasional explosions producing ash plumes up to 5.5 km altitude, as well as gas-and-steam plumes and a persistent thermal anomaly with incandescence visible at night. Starting in late February thermal anomalies were detected much more frequently, and with higher energy output compared to the previous year (figure 35). A lava fountain was reported on 1 March with the material falling back into the summit crater. Strombolian activity continued through early March. Lava fountaining was reported again on the 8th with ejecta landing in the crater and down the flanks (figure 36). A strong persistent gas-and-steam plume containing some ash continued along with Strombolian activity through 25 March (figure 37), with Vulcanian activity noted on the 20th and 25th. Strombolian and Vulcanian activity was reported through the end of March.

Figure (see Caption) Figure 35. This MIROVA thermal energy plot for Klyuchevskoy for the year ending 29 April 2020 (log radiative power) shows intermittent thermal anomalies leading up to more sustained energy detected from February through March, then steadily increasing energy through April 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 36. Strombolian explosions at Klyuchevskoy eject incandescent ash and gas, and blocks and bombs onto the upper flanks on 8 and 10 March 2020. Courtesy of IVS FEB RAS, KVERT.
Figure (see Caption) Figure 37. Weak ash emission from the Klyuchevskoy summit crater are dispersed by wind on 19 and 29 March 2020, with ash depositing on the flanks. Courtesy of IVS FEB RAS, KVERT.

Activity was dominantly Strombolian during 1-5 April and included intermittent Vulcanian explosions from the 6th onwards, with ash plumes reaching 6 km altitude. On 18 April a lava flow began moving down the SE flank (figures 38). A report on the 26th reported explosions from lava-water interactions with avalanches from the active lava flow, which continued to move down the SE flank and into the Apakhonchich chute (figures 39 and 40). This continued throughout April and May with sustained Strombolian and intermittent Vulcanian activity at the summit (figures 41 and 42).

Figure (see Caption) Figure 38. Strombolian activity produced ash plumes and a lava flow down the SE flank of Klyuchevskoy on 18 April 2020. Courtesy of IVS FEB RAS, KVERT.
Figure (see Caption) Figure 39. A lava flow descends the SW flank of Klyuchevskoy and a gas plume is dispersed by winds on 21 April 2020. Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.
Figure (see Caption) Figure 40. Sentinel-2 thermal satellite images show the progression of the Klyuchevskoy lava flow from the summit crater down the SE flank from 19-29 April 2020. Associated gas plumes are dispersed in various directions. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 41. Strombolian activity at Klyuchevskoy ejects incandescent ejecta, gas, and ash above the summit on 27 April 2020. Courtesy of D. Bud'kov, IVS FEB RAS, KVERT.
Figure (see Caption) Figure 42. Sentinel-2 thermal satellite images of Klyuchevskoy show the progression of the SE flank lava flow through May 2020, with associated gas plumes being dispersed in multiple directions. Courtesy of Sentinel Hub Playground.

Geologic Background. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Nyamuragira (DR Congo) — June 2020 Citation iconCite this Report

Nyamuragira

DR Congo

1.408°S, 29.2°E; summit elev. 3058 m

All times are local (unless otherwise noted)


Intermittent thermal anomalies within the summit crater during December 2019-May 2020

Nyamuragira (also known as Nyamulagira) is located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo and consists of a lava lake that reappeared in the summit crater in mid-April 2018. Volcanism has been characterized by lava emissions, thermal anomalies, seismicity, and gas-and-steam emissions. This report summarizes activity during December 2019 through May 2020 using information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

According to OVG, intermittent eruptive activity was detected in the lava lake of the central crater during December 2019 and January-April 2020, which also resulted in few seismic events. MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows thermal anomalies within the summit crater that varied in both frequency and power between August 2019 and mid-March 2020, but very few were recorded afterward through late May (figure 88). Thermal hotspots identified by MODVOLC from 15 December 2019 through March 2020 were mainly located in the active central crater, with only three hotspots just outside the SW crater rim (figure 89). Sentinel-2 thermal satellite imagery also showed activity within the summit crater during January-May 2020, but by mid-March the thermal anomaly had visibly decreased in power (figure 90).

Figure (see Caption) Figure 88. The MIROVA graph of thermal activity (log radiative power) at Nyamuragira during 27 July through May 2020 shows variably strong, intermittent thermal anomalies with a variation in power and frequency from August 2019 to mid-March 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 89. Map showing the number of MODVOLC hotspot pixels at Nyamuragira from 1 December 2019 t0 31 May 2020. 37 pixels were registered within the summit crater while 3 were detected just outside the SW crater rim. Courtesy of HIGP-MODVOLC Thermal Alerts System.
Figure (see Caption) Figure 90. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) confirmed ongoing thermal activity (bright yellow-orange) at Nyamuragira from February into April 2020. The strength of the thermal anomaly in the summit crater decreased by late March 2020, but was still visible. Courtesy of Sentinel Hub Playground.

Geologic Background. Africa's most active volcano, Nyamuragira, is a massive high-potassium basaltic shield about 25 km N of Lake Kivu. Also known as Nyamulagira, it has generated extensive lava flows that cover 1500 km2 of the western branch of the East African Rift. The broad low-angle shield volcano contrasts dramatically with the adjacent steep-sided Nyiragongo to the SW. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Historical eruptions have occurred within the summit caldera, as well as from the numerous fissures and cinder cones on the flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Historical lava flows extend down the flanks more than 30 km from the summit, reaching as far as Lake Kivu.

Information Contacts: Information contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/exp.


Nyiragongo (DR Congo) — June 2020 Citation iconCite this Report

Nyiragongo

DR Congo

1.52°S, 29.25°E; summit elev. 3470 m

All times are local (unless otherwise noted)


Activity in the lava lake and small eruptive cone persists during December 2019-May 2020

Nyiragongo is located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo, part of the western branch of the East African Rift System and contains a 1.2 km-wide summit crater with a lava lake that has been active since at least 1971. Volcanism has been characterized by strong and frequent thermal anomalies, incandescence, gas-and-steam emissions, and seismicity. This report summarizes activity during December 2019 through May 2020 using information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

In the December 2019 monthly report, OVG stated that the level of the lava lake had increased. This level of the lava lake was maintained for the duration of the reporting period, according to later OVG monthly reports. Seismicity increased starting in November 2019 and was detected in the NE part of the crater, but it decreased by mid-April 2020. SO2 emissions increased in January 2020 to roughly 7,000 tons/day but decreased again near the end of the month. OVG reported that SO2 emissions rose again in February to roughly 8,500 tons/day before declining to about 6,000 tons/day. Unlike in the previous report (BGVN 44:12), incandescence was visible during the day in the active lava lake and activity at the small eruptive cone within the 1.2-km-wide summit crater has since increased, consisting of incandescence and some lava fountaining (figure 72). A field survey was conducted on 3-4 March where an OVG team observed active lava fountains and ejecta that produced Pele’s hair from the small eruptive cone (figure 73). During this survey, OVG reported that the level of the lava lake had reached the second terrace, which was formed on 17 January 2002 and represents remnants of the lava lake at different eruption stages. There, the open surface lava lake was observed; gas-and-steam emissions accompanied both the active lava lake and the small eruptive cone (figures 72 and 73).

Figure (see Caption) Figure 72. Webcam image of Nyiragongo in February 2020 showing an open lava lake surface and incandescence from the active crater cone within the 1.2 km-wide summit crater visible during the day, accompanied by white gas-and-steam emissions. Courtesy of OVG (Rapport OVG February 2020).
Figure (see Caption) Figure 73. Webcam image of Nyiragongo on 4 March 2020 showing an open lava lake surface and incandescence from the active crater cone within the 1.2 km-wide summit crater visible during the day, accompanied by white gas-and-steam emissions. Courtesy of OVG (Rapport OVG Mars 2020).

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data continued to show frequent strong thermal anomalies within 5 km of the summit crater through May 2020 (figure 74). Similarly, the MODVOLC algorithm reported multiple thermal hotspots almost daily within the summit crater between December 2019 and May 2020. These thermal signatures were also observed in Sentinel-2 thermal satellite imagery within the summit crater (figure 75).

Figure (see Caption) Figure 74. Thermal anomalies at Nyiragongo from 27 July through May 2020 as recorded by the MIROVA system (Log Radiative Power) were frequent and strong. Courtesy of MIROVA.
Figure (see Caption) Figure 75. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) showed ongoing thermal activity (bright yellow-orange) in the summit crater at Nyiragongo during January through April 2020. Courtesy of Sentinel Hub Playground.

Geologic Background. One of Africa's most notable volcanoes, Nyiragongo contained a lava lake in its deep summit crater that was active for half a century before draining catastrophically through its outer flanks in 1977. The steep slopes of a stratovolcano contrast to the low profile of its neighboring shield volcano, Nyamuragira. Benches in the steep-walled, 1.2-km-wide summit crater mark levels of former lava lakes, which have been observed since the late-19th century. Two older stratovolcanoes, Baruta and Shaheru, are partially overlapped by Nyiragongo on the north and south. About 100 parasitic cones are located primarily along radial fissures south of Shaheru, east of the summit, and along a NE-SW zone extending as far as Lake Kivu. Many cones are buried by voluminous lava flows that extend long distances down the flanks, which is characterized by the eruption of foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities, as did lava flows that inundated portions of the major city of Goma in January 2002.

Information Contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Kavachi (Solomon Islands) — May 2020 Citation iconCite this Report

Kavachi

Solomon Islands

8.991°S, 157.979°E; summit elev. -20 m

All times are local (unless otherwise noted)


Discolored water plumes seen using satellite imagery in 2018 and 2020

Kavachi is a submarine volcano located in the Solomon Islands south of Gatokae and Vangunu islands. Volcanism is frequently active, but rarely observed. The most recent eruptions took place during 2014, which consisted of an ash eruption, and during 2016, which included phreatomagmatic explosions (BGVN 42:03). This reporting period covers December 2016-April 2020 primarily using satellite data.

Activity at Kavachi is often only observed through satellite images, and frequently consists of discolored submarine plumes for which the cause is uncertain. On 1 January 2018 a slight yellow discoloration in the water is seen extending to the E from a specific point (figure 20). Similar faint plumes were observed on 16 January, 25 February, 2 March, 26 April, 6 May, and 25 June 2018. No similar water discoloration was noted during 2019, though clouds may have obscured views.

Figure (see Caption) Figure 20. Satellite images from Sentinel-2 revealed intermittent faint water discoloration (yellow) at Kavachi during the first half of 2018, as seen here on 1 January (top left), 25 February (top right), 26 April (bottom left), and 25 June (bottom right). Images with “Natural color” rendering (bands 4, 3, 2); courtesy of Sentinel Hub Playground.

Activity resumed in 2020, showing more discolored water in satellite imagery. The first instance occurred on 16 March, where a distinct plume extended from a specific point to the SE. On 25 April a satellite image showed a larger discolored plume in the water that spread over about 30 km2, encompassing the area around Kavachi (figure 21). Another image on 30 April showed a thin ribbon of discolored water extending about 50 km W of the vent.

Figure (see Caption) Figure 21. Sentinel-2 satellite images of a discolored plume (yellow) at Kavachi beginning on 16 March (top left) with a significant large plume on 25 April (right), which remained until 30 April (bottom left). Images with “Natural color” rendering (bands 4, 3, 2); courtesy of Sentinel Hub Playground.

Geologic Background. Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is one of the most active submarine volcanoes in the SW Pacific, located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi ("Kavachi's Oven"), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.

Information Contacts: Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

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Bulletin of the Global Volcanism Network - Volume 38, Number 05 (May 2013)

Managing Editor: Richard Wunderman

Agrigan (United States)

2007 M~3.3 earthquake followed by clouds of equivocal origin

Ambae (Vanuatu)

Minor activity likely continuing into early 2013

Ambrym (Vanuatu)

Roiling lava lake and related observations through mid-2013

Dallol (Ethiopia)

Phreatic eruption in 1st week of January 2011

Fuego (Guatemala)

Continuous activity and a VEI 3 eruption during 13-14 September 2012

Gaua (Vanuatu)

Hazard status raised; emissions continue into 2013; plume observed from above

Kilauea (United States)

Summary of highlights for 2010-2012

Pavlof (United States)

Eruption in May-June 2013 with lava flows and ash emissions to ~8.5 km a.s.l.

Veniaminof (United States)

Ongoing sporadic eruptions as late as 6 October 2013

Yasur (Vanuatu)

Explosive activity continued into at least early 2013



Agrigan (United States) — May 2013 Citation iconCite this Report

Agrigan

United States

18.77°N, 145.67°E; summit elev. 965 m

All times are local (unless otherwise noted)


2007 M~3.3 earthquake followed by clouds of equivocal origin

Our last report on Agrigan volcano covered a May 1992 field visit (BGVN 17:06) by a six-member team of USGS volcanologists that visited the Commonwealth of the Northern Mariana Islands (CNMI) at the request of the CNMI Office of Civil Defense. The team detected thermal activity, but no seismicity, deformation or other signs of an eruption.

The following came from a report by both the USGS and CNMI issued mid-July 2007and labeled Current Update. "An earthquake was reported felt on Agrigan island at 3:49 pm July 16 local time. About 3 seconds of shaking was reported by a local resident. Seismometers on Sarigan and Anatahan recorded the earthquake and allowed estimation the magnitude at approximately 3.3. No sulfur smell or any other signs of volcanic activity were reported on July 16 or in a follow up call on July 17."

Some 2012 and 2013 observations were equivocal. On 29 February 2012, NOAA's Washington Volcanic Ash Advisory Center (VAAC) inferred ash and gas emissions here for the first time on record, but this was later discounted due to lack of forthcoming evidence. The inferred plume was seen in satellite infrared imagery. It extended 74 km NW from the summit.

A possible volcanic plume from Agrigan was spotted again by the VAAC in a satellite image from 22 January 2013.

In a 25 January 2013 USGS update, it was noted that neither the USGS nor NOAA received confirmation of a volcanic source for the satellite anomalies. The authors of the 2013 update interpreted the cloud as weather-related and not volcanic in origin.

Figure 2 shows a photo of Agrigan taken in June 2013. No hotspots were detected during mid-2012 to mid-2013 by the MODVOLC Thermal Alerts System.

Figure (see Caption) Figure 2. Agrigan as seen on 15 June 2013. Photo credit to Yoshi Tamura; featured here thanks to cooperation of Robert Stern.

Agrigan, the highest-standing stratovolcano and largest (by subaerial volume) in the Northern Mariana Islands, stands 882 m a.s.l (figure 3). The island is ~10 by 6.5 km (N-S by E-W) in size, with a surface area of 52.7 km2. The volcano's subaerial volume is ~15.9 km3. The summit contains a large depression, roughly 1.5 by 1.2 km in diameter, and 380 m deep. A spatter cone and flows from the 1917 eruption cover ~50 percent of the crater floor. This large crater implies a local edifice with shallow magma storage within the volcano. The flanks of the volcano are steep (>30 degrees), with deep furrows extending radially away from the crater. To the north is a large canyon into which a recent, large 'a'&#257 flow advanced to form a delta on the coast. Pyroclastic flow deposits mantle most of the interior of the island. Rocks erupted on the island range from basalt to andesite. The southwest coast has several beaches composed of mineral sands; otherwise, the coast is rocky. (Trusdell, F.A. and others, 2009).

Figure (see Caption) Figure 3. Geologic map of Agrigan with 200 m contour intervals (after Stern, 1978) and location map (after Trusdell and others, 2006).

References. Sako, M. K.; Trusdell, F. A.; Koyanagi, R. Y.; Kojima, George; Moore, R. B., 1995, Volcanic investigations in the Commonwealth of the Northern Mariana Islands, April to May 1994, USGS Open-File Report 94-705.

Stern, R.J., 1978, Agrigan: an introduction to the geology of an active volcano in the Northern Mariana Arc: Bulletin of Volcanology, v. 41, p. 43-55.

Trusdell, F.A., Moore, R.B., and Sako, M.K., 2006. Preliminary Geologic Map of Mount Pagan Volcano, Pagan Island, Commonwealth of the Northern Mariana Islands, USGS Open-File Report 2006-1386 (URL: http://pubs.usgs.gov/of/2006/1386/).

Trusdell, F.A. 2009, Geology of the Mariana Islands, in Gillespie, R.G., and Clague, D.A., eds., Encyclopedia of Islands: Enclyclopedias of the Natural World, 2, University of California Press, Chap. 18. P. 598-603.

Geologic Background. The highest of the Marianas arc volcanoes, Agrigan contains a 500-m-deep, flat-floored caldera. The elliptical island is 8 km long; its summit is the top of a massive 4000-m-high submarine volcano. Deep radial valleys dissect the flanks of the thickly vegetated stratovolcano. The elongated caldera is 1 x 2 km wide and is breached to the NW, from where a prominent lava flow extends to the coast and forms a lava delta. The caldera floor is surfaced by fresh-looking lava flows and also contains two cones that may have formed during the only historical eruption in 1917. This eruption deposited large blocks and 3 m of ash and lapilli on a village on the SE coast, prompting its evacuation.

Information Contacts: Emergency Management Office of the Commonwealth of the Northern Mariana Islands (EMO-CNMI) and USGS Volcano Hazards Program, PO Box 100007, Saipan, MP 96950, USA (URL: http://www.cnmihsem.gov.mp/ and http://volcanoes.usgs.gov/nmi/activity/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL://httphotspot.higp); Robert J. Stern, University of Texas at Dallas, 800 W Campbell Rd Richardson, TX 75080; and Yoshi Tamura, Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan.


Ambae (Vanuatu) — May 2013 Citation iconCite this Report

Ambae

Vanuatu

15.389°S, 167.835°E; summit elev. 1496 m

All times are local (unless otherwise noted)


Minor activity likely continuing into early 2013

In our May 2011 Bulletin we reported that there was increased degassing at Aoba (also known as Ambae) starting December 2009 through at least April 2010. This report summarizes notices pereiodically posted by the Vanuatu Geohazards Observatory (VGO) and covers the time interval from 4 June 2011 through 26 February 2013. The Vanautu Volcano Alert Level (VVAL) remained at 1 (on a scale of 0-4.)

Observations on 4 June 2011 revealed that small explosions had been occurring from the crater lake and were accompanied by local ashfall around the crater. Some villagers in the N and W parts of the island had observed the explosions.

Based on analysis of data collected by the Vanuatu Meteorology and Geohazards Department (VMGD), the Vanuatu Geohazards Observatory reported that a small series of explosions from Aoba occurred on 10 July 2011. On July 11, VGO noted that there had been recent increases in activity from Ambae and that local earthquakes were volcanic. Satellite images collected by the Ozone Monitoring Instrument showed sulfur dioxide emissions. Photos showed that the volcano was quiet on 12 July 2011, although ongoing earthquakes were detected.

According to the VGO, Ambanga villagers reported that minor activity at Aoba began in December 2012. The OMI instrument detected strong gas emissions on 18 and 25 January 2013; the emissions continued at a lower level through 7 February. Field observations by the Geohazards team during 30 January-2 February 2013 confirmed that activity had significantly changed. Data retrieved from a monitoring station also confirmed ongoing activity. Satellite images acquired on 3 and 26 February 2013 detected substantial sulfur dioxide emissions.

No MODVOLC Thermal Alerts were issued in the previous year ending 16 July 2013.

Geologic Background. The island of Ambae, also known as Aoba, is a massive 2,500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Information Contacts: Vanuatu Geohazards Observatory (URL: http://www.vmgd.gov.vu/vmgd/); and Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Ambrym (Vanuatu) — May 2013 Citation iconCite this Report

Ambrym

Vanuatu

16.25°S, 168.12°E; summit elev. 1334 m

All times are local (unless otherwise noted)


Roiling lava lake and related observations through mid-2013

In our previous Ambrym report, we described ongoing plumes, some bearing ash rising to over 6 km altitude through early June 2011 (BGVN 36:05). The volcano has been known to contain two molten, turbulent lava lakes since August 1999, and that continues at least through June 2011, which was the last time lava-lake activity was noted in a report by the Vanuatu Geohazards Observatory (VGO). Our reporting observations drew heavily on government reports of 3 April 2009 and 29 July 2013. The former report also discussed water supply and other issues of public health and safety associated with inhabiting an active volcano. Vanuatu is located in the South Pacific NE of Australia (figures 24 and 25).

Figure (see Caption) Figure 24. A location map showing Ambrym volcano on Ambrym Island in the South Pacific. Australia is at lower left. On larger map, Ambrym is shown in Vanuatu labeled in red. Map came from Polacci and others (2012).
Figure (see Caption) Figure 25. Map of Ambrym emphasizing risk. Green is low hazard, yellow is medium hazard, and red is high hazard for both areas near the crater and along main stream valleys and their lower, less confined areas at low elevation. Note the two craters, Marum and Benbow, both containing active lava lakes. Courtesy of the Government of Vanuatu (from the 3 April 2009 report by the Vanuatu Natural Disaster Committee).

Reynolds (2010) posted videos of lava lake behavior seen in September 2010. Figure 26 is a screenshot taken from the Reynolds' video of the turbulent lava lake with a climber in the foreground. The high definition videos showed an exceedingly agitated lake surface, everywhere disturbed and molten, without any chilled material in evidence. Violent upwellings of lava occurred continuously. Some fraction of the videos show climbers in the foreground, at one point descending a steep slope or vertical drop by a single rope secured from above (abseiling or rappelling).

Figure (see Caption) Figure 26. A screen capture from a video of Marum, one of Ambrym's two active lava lakes, taken on unstated day in September 2010. Courtesy of James Reynolds (typhoonfury.com and earthuncut.tv).

On 27 June 2011, the VGO reported that data collected from Ambrym's monitoring network showed significant daily degassing and occasional explosions in the crater. Field observers noted that the level of the lava lakes was high. During June, villages reported minor ashfall and that acid rain affected agriculture in general in some areas W, S, and E. The Alert Level remained at 1 (on a scale of 0-4).

During the previous 12 months prior to mid-July 2013, MODVOLC thermal alerts were frequent, on the order of several a week to multiple per day, as would be expected for a volcano with active lava lakes. The alerts referred to the lava lakes in Benbow and Marum craters (figure 25).

On 21 June 2013, VGO reported that satellite images on 2, 4, 11, 14, and 16 June detected gas emissions from Ambrym. Emissions of minor amounts of ash and substantial amounts of gas from the active vents had been detected during the previous week. The report warned that communities on the island, especially those downwind of Ambrym, may experience ashfall and acid rain that could damage the environment and contaminate water. The Alert Level remained at 1. Based on pilot observations and analyses of satellite imagery, the Wellington Volcanic Ash Advisory Center (VAAC) reported that on 19 July 2013 an ash plume rose to an altitude of 3 km a.s.l. and drifted 185 km NW.

VGO reported that activity at Ambrym slightly increased to a minor eruptive phase, and a seismic swarm was detected between 2400 and 0700 on 26 July 2013. The Alert Level remained at 1.

Gas fluxes are generally high for Vanuatu volcanoes and have been the subject of regular reporting online and several recent reports in the literature (for example, Bani and others, 2009; Bani and others, 2012).

References. Bani, P., C. Oppenheimer, V.I. Tsanev, S.A. Carn, S.J. Cronin, R. Crimp, J.A. Calkins, D. Charley, M. Lardy, and T.R. Roberts, 2009, Surge in sulfur and halogen degassing from Ambrym volcano, Vanuatu, Bulletin of Volcanology, 71(10), 1159-1168, doi:10.1007/s00445-009-0293-7.

Bani, P., C. Oppenheimer, P. Allard, H. Shinohara, V. Tsanev, S. Carn, M. Lardy, and E. Garaebeti, 2012, First arc-scale volcanic SO2 budget for the Vanuatu archipelago, Journal of Volcanology and Geothermal Research, 211-212, 36-46, doi:10.1016/j.jvolgeores.2011.10.005.

Polacci, M, Baker, D, La Rue, A., Mancini, L., Allard, P., 2012, Degassing behaviour of vesiculated basaltic magmas: an example from Ambrym volcano, Vanuatu Arc, Journal of Volcanology and Geothermal Research, Vol. 233-234, 1 July 2012, pp. 55-64.

Reynolds, J., 2010, (Video) Abseiling towards a lava lake--extreme video From Marum volcano, Ambrym, Vanuatu (September 2010) YouTube (URL: https://www.youtube.com/watch?v=AtGT-_7Xoal) [also available at typhoonfury.com and earthuncut.tv].

Geologic Background. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides Arc. A thick, almost exclusively pyroclastic sequence, initially dacitic then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major Plinian eruption with dacitic pyroclastic flows about 1,900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.

Information Contacts: Vanuatu Geohazards Observatory, Department of Geology, Mines and Water Resources of Vanuatu (URL: http://geohazards.gov.vu/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Sciences and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http//hotspot.higp.hawaii.edu/); Wellington Volcanic Ash Advisory Centre (VAAC) (URL: http://vaac.metservice.com/); and NASA Global Sulfur Dioxide Monitoring Home Page, Goddard Space Flight Center, Sciences and Exploration Atmospheric Chemistry and Dynamics Laboratory, Code 614 (URL: http://so2.gsfc.nasa.gov/, http://so2.gsfc.nasa.gov/pix/daily/0813/vanuatu_0813z.html).


Dallol (Ethiopia) — May 2013 Citation iconCite this Report

Dallol

Ethiopia

14.242°N, 40.3°E; summit elev. -48 m

All times are local (unless otherwise noted)


Phreatic eruption in 1st week of January 2011

The Dallol volcano has not been the subject of any previous Bulletin reports; however, the hydrothermal features include diverse brightly colored hot springs that are both dramatic and intriguing. An explosive event at Dallol was noted by observers in January 2011. This report was given to us by Tadiwos Chernet.

Dallol is located in the Danakil Depression in the northern part of the Afar triangle of Ethiopia. The volcano is on the NNW trending Erta Ale axial, a rift segment that hosts a number of active volcanoes, including Erta Ale, itself the host of a perennial lava lake. The elliptical Dallol (figure 1), which rises gently to 60 m above the salt plain (48 m below sea level), has a summit crater (about 100 m diameter) that experienced a phreatic eruption in 1926.

Figure (see Caption) Figure 1. Dallol with salt pools and deposits in the foreground. Photograher uncertain but this photo was apparently online since 2011. Bulletin editors found it on multiple websites including Vieweird.com.

Nearby residents of Almeda observed unusual dark colored smoke from the Dallol crater in the first week of January 2011. The event, which was not strong enough to be recorded by satellite remote sensing, left dark-gray ash and sulfur deposits at Dallol hot springs, suggesting degassing from depth. This process was not unexpected given that the region contains many craters, and the Dallol crater, formed in 1926, was the result of a phreatic eruption. Previous phreatic eruptions at Dallol and the surrounding salt plain have left behind bubbling acid brine pools best explained by a number of active maar craters. Those craters are obscured by the thick evaporite succession and frequent marine invasions of the salt plain during the Holocene.

Evaporites and Geothermal reservoir. According to Chernet, an adjacent salt-crusted depression that lies 120 m below sea level was linked to the Gulf of Zula on the Red Sea in the Pleistocene by the narrow extensional Alid graben to the N. The Alid graben is floored by fissure basalts and the active Alid and Jallua rhyolitic volcanoes. An evaporite succession in the sedimentary basin is mostly bedded halite, but includes minor inter-beds of clay shale, gypsum, anhydrite, and a thick bed of potash. Citing Barberi et al. (1972), Chernet indicated that the deposits, over 1,000 m thick, have continued for 200,000-25,000 years and attest to a number of marine ingressions into the depression which have left behind a number of brine lakes.

At Dallol, a salt dome rises as a notable topographic and geologic feature (figure 1). On the salt dome, several springs with boiling, supersaturated, and extremely acidic waters are discharging on salt cones.

Citing Varet (2010), Chernet stated that geothermal reservoirs, which reside below the evaporite succession, evidently recharge from precipitation on the NW plateau. This suggests the potential for a renewable geothermal energy supply in the area.

Figure (see Caption) Figure 2. (a & b) Two, 3-dimensional representations of the Dallol dome and the subsurface spring sources venting at the surface to feed surface evaporites. Courtesy of Research and Development Center, (Ministry of Mines, P.O. Box 486, Addis Ababa, Ethiopia). Courtesy of Carniel and others (2010), citing a personal communications from M. Rivas (2006).

The salt cones are tall, brilliantly colored mounds of salt with intervening pools of yellow, orange and blue-green brine. These colors may result from oxidation state of species in solution, such as ferrous chloride to ferric chloride.

Dallol waters are characterized by very high total dissolved solids (up to 525 g/kg). The waters can be grouped into three chemical suites, all of which contain high levels of chloride. Two representative water samples were collected and analyzed. One of the samples was from a hot springs with a 110C temperature that solidified shortly after collection, indicating salt supersaturation. An X-ray diffraction pattern of the solidified product showed the presence of bishofite (MgCl2*6H2O). The other was a brine water of pH 0.2. The chemical composition of the samples was that of concentrated sea water.

According to Chernet, X-ray diffraction of samples from hydrothermal deposits within the crater shows that the major constitutents of most samples are halite, sulfur, calcite,. sodalite, and hematite, with minor levels of silica. Metallic oxides and potassium and/or fluorine impurities have given the sites a brown, yellow, or bluish color.

Chernet noted that frequent earthquakes of magnitude 4.5-5.5 occur in the vicinity of Dallol, as reflected by cracks healed with later salt deposits and a number of phreatic eruptions.

References. Barberi, F., Borsi, S., Ferrara, G., Marinelli, G.; Santacroce, R.; Tazieff, H., Varet, J., 1972, Evolution of the Danakil depression (Afar, Ethiopia) in light of radiometric age determinations, The Journal of Geology, v. 80, iss. 6, p. 720-729.

Carniel, R., Muñoz Jolis, E., Jones, J., 2010, A geophysical multi-parametric analysis of hydrothermal activity at Dallol, Ethiopia, Journal of African Earth Sciences, vol. 58, p. 812-819. (Article cited personal communications from M. Rivas, 2006).

Chernet, T., Dallol Volcano and Danakil Depression: Earth Resources and Geo-hazards, 2012, Magmatic Rifting and Active Volcanism Conference, 11-13 January 2012, (Session 3), Afar Rift Consortium, Addis Ababa, Ethiopia. (http://www.see.leeds.ac.uk/afar/new-afar/conference/talks.html).

Darraha, T.H., Tedesco, D., Tassid, F., Vasellid, O., Cuocob, E., Poredaf, RJ, 2013, Gas chemistry of the Dallol region of the Danakil Depression in the Afar region of the northern-most East African Rift, Chemical Geology, vol. 339, p. 16-29.

Nobile, A., C. Pagli, Keir, D., Wright, T. J., Ayele, A., Ruch, J., and Acocella, V., 2012, Dike-fault interaction during the 2004 Dallol intrusion at the northern edge of the Erta Ale Ridge (Afar, Ethiopia), Geophys. Res. Lett., v. 39, L19305.

Varet, J., 2010, Contribution to Favorable Geothermal Site Selection In the Afar Triangle, ARGEO-C3, Third East African Rift Geothermal Conference, Djibouti, 22-25 November 2010, p. 139-154.

Geologic Background. Numerous phreatic explosion craters dot the Salt Plain NNE of the Erta Ale Range in one of the lowest areas of the desolate Danakil depression. These craters mark Earth's lowest known subaerial volcanic vents. The most recent of these craters, Dallol, lies 48 m below sea level and was formed during an eruption in 1926. Colorful hot brine springs are found in the Dallol area. Another phreatic explosion was observed in January 2011.

Information Contacts: Tadiwos Chernet, Research and Development Directorate, Ministry of Mines, P.O.Box 486, Addis Ababa, Ethiopia.


Fuego (Guatemala) — May 2013 Citation iconCite this Report

Fuego

Guatemala

14.473°N, 90.88°W; summit elev. 3763 m

All times are local (unless otherwise noted)


Continuous activity and a VEI 3 eruption during 13-14 September 2012

In this report we highlight Fuego's ongoing eruptive activity during January 2011-March 2013. Elevated activity occurred during May-September 2012 and included regular thermal, gas, and ash emissions with occasional lava fountaining and pyroclastic flows. Activity peaked during 13-14 September 2012 with a VEI 3 (Volcanic Explosivity Index; where 3 is considered moderate (Newhall and Self, 1982)) summit eruption and SW-directed pyroclastic flow.

During this reporting period, continuous monitoring efforts by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) included seismic monitoring, regular ground-based observations, and field visits. The Washington Volcanic Ash Advisory Center (VAAC) regularly included monitoring data from INSIVUMEH with satellite remote sensing emissions announcements. We also summarize a recent international collaboration between INSIVUMEH and the International Volcano Monitoring Fund (IVM-Fund) during 2010-2013.

Local observers reported ashfall, shockwaves, and lahars. According to INSIVUMEH, during 2011-2013, ashfall and explosive sounds were frequently reported by communities located within the W sector and up to 8 km of Fuego's summit. Lahars occurred on the S-sector flank in the Taniluyá, Ceniza, Santa Teresa, Las Lajas, and Trinidad drainages (figure 16). Those drainages were also hazardous due to channelization of pyroclastic flows, block avalanches, and lava flows (figure 17); significant events occurred in mid-to-late 2012 and February 2013 (described later in this report). On the SE flank, Las Lajas was frequently affected by pyroclastic flows, and the drainages Taniluyá and Ceniza (SW flank) occasionally contained active lava flows and block avalanches.

Figure (see Caption) Figure 16. This location map includes villages (numbered), observation sites in Panimaché I (FO-1) and Sangre de Cristo (FO-2), and primary drainages located within 15 km of Fuego's summit vent (red star). Elevation contours are shown for 100 m intervals. Pyroclastic flow deposits from 13 September 2012 are shown as dark gray areas within Ceniza, Trinidad, El Jute, and Las Lajas drainages. Courtesy of Rüdiger Escobar-Wolf (Michigan Technological University).
Figure (see Caption) Figure 17. This annotated photograph is centered on Fuego's SW flank, the location of the Ceniza drainage, which channeled the major pyroclastic flow of 13 September 2012. The yellow dotted line marks the centerline of the pyroclastic flow; the orange lines enclose the region burned and scoured by ash cloud surges. Courtesy of INSIVUMEH.

Thermal anomaly detection during 2011-2013. Hotspots from the summit region were detected by satellite remote sensing instruments including MODIS (onboard the Terra and Aqua satellites), Landsat 7, and EO-1 Advanced Land Imaging (ALI) throughout this reporting period.

The MODVOLC thermal alert system recorded ~90 significant anomalies between 1 January 2011 and 1 January 2012, ~375 between 1 January 2012 and 1 January 2013 when explosive activity escalated, and ~255 between 1 January 2013 and 31 March 2013 when lava flows were active near the summit region (figure 18). Thermal anomalies were detected by satellite images at least once per month from January 2011 through March 2013 except for July 2011, suggesting poor weather may have inhibited satellite observations that month (note that heaviest rainfall typically occurs during June-October (The World Bank, 2013)). During July 2011, ground-based observations of nighttime incandescence were noted in INSIVUMEH's Report # 1863; other reports that month highlighted the effects of heavy rain from tropical storms and Hurricane Calvin.

Figure (see Caption) Figure 18. During 1 January 2011-31 March 2013, the MODVOLC system frequently detected elevated temperatures in the area of Fuego's summit. This series of images includes hotspots detected during three time periods: 2011, 2012, and 1 January-31 March 2013. Courtesy of the Hawai`i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System.

MODVOLC continued to detect hotspots during late April 2013 totaling 22 pixels during 21-28 April. Thermal anomalies became rare during May and June 2013; one pixel was detected on three different days.

Regular images captured by ALI and Landsat 7 detected variable incandescence from Fuego's summit during 2011-2013 (figure 19). During 2011, hotspots were mainly located at Fuego's summit; however, during March and December, distinctively elongate, incandescent lava flows extended from the summit to the SW (figure 19A and 19B).

Figure (see Caption) Figure 19. Satellite images from 2011-2013 detected incandescence from Fuego's summit area. (A) This ALI image from 3 February 2011 showed a small region of incandescence isolated at the summit. (B) A Landsat 7 image from 7 November 2011 revealed a ~300 m incandescent flow originating from the summit and extending down the SW flank. (C) This Landsat 7 image from 4 September 2012 (nine days before the VEI 3 eruption began) captures intense incandescence that extends in three directions from the summit; some image distortion is present from cloudcover and artifact stripes (on the left-hand side). Distinctive yellow regions indicate lava reaching at least 500 m SE and SW. (D) This ALI image from 20 March 2013 captures a lava flow extending ~1,500 m SW from the summit crater within the upper region of the Ceniza drainage; some cloudcover blocks the middle region of the lava flow, but the red glow is visible and especially bright at the termination point SW of the clouds. Image processing by Rüdiger Escobar-Wolf (Michigan Technological University); courtesy of NASA/USGS.

Summit incandescence extending SW, SE, and in the immediate summit area was visible during 2012; some of the strongest incandescence extended at least 1 km from the summit to the SW during November-December. Incandescent flows directed SE appeared in April, June, and September. On 4 September 2012, three narrow flows were visible from the summit extending ≥ 500 m from the summit within the S sector; despite significant cloudcover that day and image artifacts, the lava flows were well-defined (figure 19C).

Satellite images from December 2012 through January 2013 included a long lava flow that persisted in the SW drainage (Ceniza), although cloudcover frequently obscured the full view of Fuego's SW quadrant. That incandescent lava flow remained visible in satellite images until late February 2013. Incandescence was isolated at the summit in early March, but on 20 March incandescence re-appeared within the Ceniza drainage and extended ~2,000 m SW of the summit (figure 19D).

Effusive activity during 2011-2013. The style of eruptive activity at Fuego changed near the end of 2010 when lava effusion events started to occur more frequently than explosive eruptions (figure 20). "At a very general level, the more Strombolian eruptions happen typically during lava effusion times and are much smaller than the more Vulcanian eruptions," commented Rüdiger Escobar-Wolf (Michigan Technological University) with respect to Fuego's more than 12 year-long eruption. Continuous unrest (background-level explosions and effusion) was frequently punctuated by short periods of elevated activity during the preceding six years and, during 2012 and 2013, this activity was interrupted by several significant episodes: in 2012, 25-26 May; 10-11 June; 3-4 and 13-14 September; and in 2013, 17-18 February; 3-4 and 19-20 March (figure 19D).

Figure (see Caption) Figure 20. Fuego time series from late 1999 to early 2013 with color codes indicating eruption style (Escobar-Wolf, 2013). Beginning in 1999, the eruption mainly consisted of periods of explosive events (color coded as green) and lava effusion (coded as gray); this constant unrest is considered background activity that has been occasionally interrupted with significant episodes (red lines). This timeline was created and provided by Rüdiger Escobar-Wolf, Michigan Technological University.

The Washington VAAC released an increasing number of notices for the aviation community about volcanic ash throughout 2011- March 2013 (table 8). During 2011, these announcements rarely contained calculated plume altitudes due to poor viewing conditions with satellite remote sensing. Data from INSIVUMEH supplemented these reports with direct observations from Fuego Volcano Observatory, located in Panimaché, 8 km SW of Fuego. On 1 January, 8 January, 23 October, and 24 December 2011, reported plume altitudes were less than 5.2 km a.s.l. and had drift speeds in the range of 2.5-10 m/s, drifting S and SW of Fuego's peak.

Table 8. The Washington VAAC released regular advisories due to emissions from Fuego during 2011-March 2013. Date, time, altitude, drift direction, and reporting sources are included as well as comments that described additional eruption characteristics such as thermal anomalies and weather conditions that may have affected observations. Drift velocities and plume width were also calculated when viewing conditions were optimal. INSIVUMEH was a frequent contributor to these reports; other reporting sources included the satellite GOES-2 (NOAA geostationary weather satellite), MWO (local Meteorological Watch Office), Guatemala City's (MGGT) meteorological reports (METAR), and the global numerical weather prediction models GFS and NAM. Courtesy of Washington VAAC.

Date - Time (UTC) Altitude (km) Drift Direction VAAC Sources Comments
01 Jan 2011 - 1515 5.2 9 km wide line; W 10 m/s GOES-13. GFS WINDS. Several small emissions.
08 Jan 2011 - 1015 5.2 18.5 km wide plume; SW 2.6-5 m/s GOES-13. GFS WINDS. Multiple exhalations since 08/0600 UTC; these explosions have been seen in satellite before dissipating.
13 Feb 2011 - 0504 -- -- GOES-13. INSIVUMEH. INSIVUMEH reported increased activity within the summit area; low height emissions of volcanic ash moving W; hot spot was also detected in short wave infrared imagery.
14 Feb 2011 - 0427 -- -- GOES-13. INSIVUMEH. INSIVUMEH continued to report low levels of volcanic ash near the summit.
15 Feb 2011 - 0427 -- -- GOES-13. INSIVUMEH. Only steam reported.
23 Oct 2011 - 1327 -- -- GOES-13. Information received about a possible volcanic ash eruption.
23 Oct 2011 - 1245 4.3 W 2.6-5 m/s GOES-13. GFS WINDS. Confidence in height of volcanic ash is medium-high based on movement and density of ash in models and satellite imagery.
22 Nov 2011 - 1530 -- -- GOES-13. INSIVUMEH. Ash observed at 1530 UTC.
22 Nov 2011 - 1745 -- -- Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH observed thin plume of possible ash moving SW at 5 m/s at 1530 UTC. This weak plume was observed in satellite imagery at 1415 UTC but had dissipated by 1545 UTC.
02 Dec 2011 - 1845 -- -- Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH reported emission of gases near the summit and light ash that was too small to see in clear satellite imagery. Ash was reported to 305 m above the summit and dispersing SW around 18.5 km.
06 Dec 2011 - 1845 -- -- GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH reported volcanic ash cloud to 3 km observed at 1600 UTC. No ash was observed in satellite imagery.
24 Dec 2011 - 1904 -- -- GOES-13. INSIVUMEH SEISMIC DETECTION. Small narrow plume of unknown content began around 1645 UTC; VAAC received information suggesting a possible ash eruption.
24 Dec 2011 - 1845 4 5.6 km wide line; S 2.5 m/s GOES-13. INSIVUMEH SEISMIC DETECTION. Small plume of gases with possible ash extended 9 km; small puff seen in visible imagery started around 1645 UTC and drifted S 2.5 m/s; estimated height 4 km a.s.l. with wind forecast uncertain. Plume was projected to dissipate within 6 hours.
25 Dec 2011 - 0015 -- -- GOES-13. A possible eruption at 1845 UTC; ash not identifiable in satellite imagery; there were no reports of ash.
03 Jan 2012 - 2041 -- -- GOES-13. Possible volcanic ash detected in visible imagery at 2015 UTC moving SE.
03 Jan 2012 - 2045 5 3.7 km wide line; S 2.6 - 5 m/s GOES-13. GFS WINDS. INSIVUMEH. Small puff seen in visible imagery at 5 km a.s.l. moving SE 3.5 m/s. At 2045 UTC the leading edge was 12 km SE of summit and dispersing. Plume was projected to dissipate within 6 hours.
16 Jan 2012 - 1724 -- -- INSIVUMEH. The VAAC received information suggesting a possible volcanic ash emission.
16 Jan 2012 - 1740 -- -- GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH reported ash to 4.3 km; no ash seen in imagery through 1715 UTC with clear skies.
18 Jan 2012 - 1215 6.7 W at 5-7.5 m/s GOES-13. GFS WINDS. Visible and multi-spectral imagery showed a single puff of gas and ash moving W from the summit; ash was projected to dissipate within a few hours as it continued W. A hotspot was detected.
01 Feb 2012 - 1645 -- -- GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH reported ash to ~5 km at 01/1600 UTC; ash not observed in satellite imagery even with sparse clouds.
01 Apr 2012 - 1315 5 9.3 km wide line; SW 2.6-5 m/s  GOES-13. GFS WINDS. NAM WINDS. Plume extended 13 km WSW from the summit; well-defined hotspot seen in imagery; forecast confidence was low based on latest GFS and NAM.
19 May 2012 - 0915 -- -- GOES-13. GFS WINDS. INSIVUMEH. Ash was not seen in satellite imagery due to darkness; hotspot was visible; INSIVUMEH reported volcanic ash up to 5.5 km a.s.l. to 40 km SW of the summit.
19 May 2012 - 1515 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. INSIVUMEH Photos. Ash was not seen in satellite imagery due to cloudcover; a strong hotspot was visible in satellite multispectral imagery; seismicity was high.
19 May 2012 - 2045 -- -- GOES-13. GFS WINDS. METAR.
INSIVUMEH.
Volcanic ash was not detected in satellite imagery due to extensive cloud cover; INSIVUMEH indicated pyroclastic flows likely and ashfalls have been observed.
20 May 2012 - 0245 -- -- GOES-13. GFS WINDS. Ash was not observed in satellite imagery due to cloudcover; hotspot had decreased in intensity and late afternoon bulletin indicated decreased energy.
20 May 2012 - 1415 -- -- GOES-13. NAM WINDS. INSIVUMEH. No ash was observed in imagery although there were thick clouds in the area; INSIVUMEH reported ash emissions up to 3,000 m above the summit moving SW.
20 May 2012 - 1945 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. No ash was seen in imagery due to cloudcover; seismic signal has almost gone to background but with very occasional bursts that may contain volcanic ash.
21 May 2012 - 0045 -- -- GOES-13. GFS WINDS. INSIVUMEH. No volcanic ash detected due to cloudcover; INSIVUMEH's evening report only mentioned occasional emission of ash to 4 km a.s.l. or just above the crater drifting SW and dispersed within 9.3 km; seismic activity was back to normal with only occasional small bursts.
25 May 2012 - 1542 -- --; GOES-13. INSIVUMEH. Eruption of lava began around 1300 UTC; some volcanic ash was possible.
25 May 2012 - 1615 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. METAR. Pilot Report. INSIVUMEH. No plume was seen in satellite imagery due to partly cloudy conditions; pilot report of ash to 7 km a.s.l. moving SW; lava flows generated volcanic ash and gas; no explosive eruption seen in the seismic records; ash was forecasted to moving SW; a strong hotspot was visible in satellite imagery.
26 May 2012 - 0415 -- -- GOES-13. GFS WINDS. Volcanic ash was not detected in satellite imagery due to extensive cloudcover; INSIVUMEH indicated constant pyroclastic flows and reports of ashfall.
26 May 2012 - 1015 -- -- GOES-13. GFS WINDS. SEISMIC
DETECTION.
Volcanic ash was not seen due to darkness and weather conditions; strong hot spot was visible in satellite imagery and seismic activity remained elevated.
26 May 2012 - 1615 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. Ash was not seen in imagery due to cloud cover; INSIVUMEH indicated that ash and gas emissions continued.
26 May 2012 - 2215 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. Ash was not seen in satellite imagery due to cloudcover; INSIVUMEH reported decreasing seismicity; a hot spot persisted in multispectral imagery.
27 May 2012 - 0415 -- -- GOES-13. INSIVUMEH. INSIVUMEH indicated ongoing lava flows; decreasing seismic activity and no mention of ashfall in the most recent report.
05 Jun 2012 - 1732 -- -- GOES-13. INSIVUMEH. INSIVUMEH reported increasing activity and suggested that an explosive eruption with little or no warning was possible; hot spot was seen in satellite imagery but no volcanic ash due to cloud cover.
06 Jun 2012 - 1729 -- -- GOES-13. INSIVUMEH. INSIVUMEH reported intermittent explosions expelling ash and gas up to ~600 m above the summit; they warned that an explosive eruption with little or no warning was possible.
07 Jun 2012 - 1715 -- -- GOES-13. INSIVUMEH. INSIVUMEH reported activity that was limited to within 11 km of the summit; no ash was visible in satellite imagery due to partly cloudy conditions.
11 Jun 2012 - 0945 -- -- Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH. No ash seen in satellite imagery due to nighttime darkness; hotspots see for last few hours. INSIVUMEH reported ash to 5 km.
11 Jun 2012 - 1545 -- -- GOES-13. INSIVUMEH. No ash was seen in imagery although there was some cloudcover; there was a strong hotspot occasionally seen in shortwave imagery; INSIVUMEH reported continuous ash emissions up to 15 km to the W and WNW of volcano.
21 Jun 2012 - 1552 -- -- Tegucigalpa MWO. GOES-13.
GEOPHYSICAL INST. EMAILED PHOTOS.
No ash detected due to cloudcover; INSIVUMEH reported ash moving E from rockfalls and aided by heat of lava flows; bit hotspots were visible through clouds.
21 Jun 2012 - 2138 -- -- GOES-13. GFS WINDS. No ash detected in visible satellite imagery due to cloudcover; hotspot seen in infrared imagery.
22 Jun 2012 - 0340 -- -- GOES-13. GFS WINDS. No ash seen in visible or multispectral satellite imagery due to night time darkness and cloudcover; hotspot observed prior to clouds moving in 22/0015 UTC.
03 Sep 2012 - 1415 4.3/5.2 5.6 km wide line; SW 5-7.5 m/s
7.4 km wide line; W 2.6-5 m/s
GOES-13. GFS WINDS. Ash plume height confidence is medium, the estimation is based on models and history of volcanic activity; a well-defined hotspot was seen overnight.
03 Sept 2012 - 2015 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. Due to clouds, no good detection of ash but before the clouds arrived, faint ash was seen W-SW as far as 27.7 km; strong hotspots due to lava flows and rockfalls.
04 Sep 2012 - 0145 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. No ash detected due to clouds and darkness; multiple hotspots were seen due to rockfalls and lava flows; some ashfall was reported SW of the summit up to 13 km.
04 Sep 2012 - 0445 4.5 W 2.6-5 m/s GOES-12. GFS WINDS. INSIVUMEH SEISMIC DETECTION. A plume was visible in multispectral imagery extending about ~145 km W of the summit.
04 Sep 2012 - 1015 4.5 W 2.6-5 m/s GOES-13. A continuous emission of ash was visible in multispectral imagery extending ~145 km W of volcano; large hotspot was detected by shortwave imagery.
04 Sep 2012 - 1615 -- -- GOES-13. GFS WINDS. INSIVUMEH. Ash was not seen due to weather conditions; strong hotspot remains in thermal imagery and INSIVUMEH reported elevated seismic activity.
04 Sep 2012 - 2145 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. No ash or hotspots detected due to thick clouds; INSIVUMEH reported continued lava flows and rockfalls that generated ash to ~4.5 km a.s.l. moving SW; ashfall was reported up to 15 m SW and W of the summit.
05 Sep 2012 - 1545 -- -- GOES-13. INSIVUMEH. Ash not seen in the satellite imagery due to partly cloudy skies; a faint hotspot was visible in the morning; INSIVUMEH confirmed that no ash emissions were detected.
13 Sep 2012 - 1115 5 W 7.5 m/s GOES-13. GFS WINDS. INSIVUMEH. Faint plume was detected with multispectral imagery that extended ~111 km W; INSIVUMEH reported ash up to 1,000 m above the summit and moving W and SW.
13 Sep 2012 - 1602 4.5 /6.7 SW 7.5 m/s / SW 7.5-10 m/s GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH reported new emission to 3,000 m above the summit W and SW of the summit. 13/1602 UTC image showed a dense ash plume spreading W and SW. Imagery through 13/1632 UTC showed dense volcanic ash emissions continuing.
13 Sep 2012 - 2045 7.3 W 10-13 m/s GOES-13. GFS WINDS. METAR.
INSIVUMEH.
Ash plume was 148 km wide and extended 226 km W of summit; ash was reported at MGGT METAR station.
14 Sep 2012 - 0045 7.3 W 10-13 m/s GOES-13. GFS WINDS. METAR.
INSIVUMEH.
Ash plume was 111 km wide and extended 417 W of the summit; ash closest to summit was obscured by cloudcover and was likely rained out; METAR from MGGT continued to report ash.
14 Sep 2012 - 0710 4.3 /7.3 W 5 m/s / W 5 m/s GOES-13. GFS WINDS. INSIVUMEH. A bright hotspot persisted with a small plume in multispectral imagery extending 36 km to the W of the summit; latest report indicated current activity was more intermittent and lower in height; larger area to 7.3 km a.s.l. continued to dissipate about 648 km to W of summit moving W.
14 Sep 2012 - 1245 4 /7.3 W 7.5-10 m/s / W 10-13 m/s GOES-13. GFS WINDS. METAR.
INSIVUMEH.
Multispectral imagery showed dissipating ash to 7.3 km a.s.l. between 370 km and 926 km W moving W; in addition, continuous attached plume to 4 km a.s.l. was seen moving SW; local surface observations reported 4 km a.s.l.
14 Sep 2012 - 1845 6 W 10 m/s GOES-13. GFS WINDS. INSIVUMEH. A dissipating area of ash, about ~1,000 km W of the summit, was detected in multispectral imagery; no ash was seen near the summit at 1845 UTC; INSIVUMEH reported ash emissions within 15 km of the summit.
15 Sep 2012 - 0045 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. No ash was detected in satellite imagery; the previous plume located S of Mexico had dispersed around 14/2200 UTC. INSIVUMEH reported weaker seismic activity with rockfalls generating ash plumes to 4 km a.s.l. and 15 km W-SW of the summit; a strong hotspot was visible.
29 Sep 2012 - 1245 -- -- GFS WINDS. GOES-14. INSIVUMEH. In the morning, satellite imagery detected discreet puffs of ash moving W and WSW from the summit; INSIVUMEH reported ash 500 m to 900 m above the summit with fine ashfall.
17 Feb 2013 - 0544 -- -- GOES-13. INSIVUMEH. INSIVUMEH reports incredible outpouring of lava from the crater which is confirmed by brilliant hot spot in satellite imagery; INSIVUMEH reported no ash plume at the moment, but emissions are possible over the next few hours up to 10 km to the S and SW of the summit.
17 Feb 2013 - 1315 5 W 2.6-5 m/s Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH. In the morning, visible imagery showed a plume of ash extending 18.5 km to the W of the volcano; INSIVUMEH reported ash to 4.8 km a.s.l.
17 Feb 2013 - 1445 5 W Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH. Imagery showed ash moving W-SW and S from the volcano; at 17/1445 UTC ash extended 18.5 km SW and 5.6 km S of the volcano.
17 Feb 2013 - 2015 5.2 0-5 m/s Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH. Ongoing emissions of lava with gas and light ash; in imagery the ash is mixed with clouds and, due to light winds spreading N-W-SW from the summit ~13 km; this is mainly a lava event but some light ashfall was being reported in cities on the slopes of the volcano.
18 Feb 2013 - 0815 -- -- GOES-13. GFS WINDS. INSIVUMEH. Ongoing lava emission with gases and light ash; no ash detected due to large thunderstorm that developed SW of summit and regional cloudcover. INSIVUMEH reported in the afternoon that less energetic lava, gas, and ash events were occurring.
03 Mar 2013 - 2345 -- -- GOES-13. GFS WINDS. INSIVUMEH. Lava emission with occasional light ash due to rockfalls and small venting; hotspot due to lava but no ash was visible in satellite imagery; plume drifted up to 9 km according to INSIVUMEH; wind forecast was light and variable, so the plume was expected to remain close to the summit region.
04 Mar 2013 - 0334 -- -- GOES-13. GFS WINDS. INSIVUMEH. An INSIVUMEH special report indicated that a new stage of emissions began and possible ash fall was likely around 18.5 km from the summit. Ash was not seen in multispectral satellite imagery; a very large hotspot was observed with infrared.
04 Mar 2013 - 0845 -- -- GOES-13. GFS WINDS. Ash was not seen in overnight satellite imagery; very large and bright hotspot was detected with infrared sensors; emissions of gas and ash were likely.
04 Mar 2013 - 1315 4.3 moving NE 5-7.5 m/s GOES-13. GFS WINDS. INSIVUMEH. Ongoing emissions; satellite imagery showed a faint ash plume 13 km wide and extending 42.5 km NE of the summit; a very bright hot spot was detected with infrared sensors.
04 Mar 2013 - 1915 -- -- GOES-13. GFS WINDS. INSIVUMEH. Ongoing emissions; ash was too light to be seen in visible satellite imagery although reports indicate that ash was present; a strong hot spot persisted.
05 Mar 2013 - 0115 -- -- Tegucigalpa MWO. GOES-13. Ongoing activity; Tegucigalpa MWO canceled Sigmet for the event; a well-defined hotspot was visible in multi-spectral imagery; no ash was present in the last visible images of the day.
18 Mar 2013 - 1345 4.3 moving SW 2.6-5 m/s Tegucigalpa MWO. GOES-13. GFS WINDS. Very light volcanic ash emissions; MWO indicated ash moving SW; the ash had a SSW component in satellite imagery and was very light in nature.
18 Mar 2013 - 1945 -- -- GOES-13. GFS WINDS. INSIVUMEH. Emissions of gas and occasional light ash were near the summit; no ash was detected or reported in cloudy conditions; INSIVUMEH reported near-summit emissions of gas and occasional, very light ash below 4.3 km a.s.l. and within 9 km of the summit.
19 Mar 2013 - 2232 -- -- GOES-13. GFS WINDS. INSIVUMEH. INSIVUMEH reported ash to 5 km a.s.l. at 19/2045 UTC moving SE at 5 m/s; ash not visible in imagery; special observatory report indicated elevated activity with the volcano; a persistent hotspot was present since 1915 UTC and had become increasingly bright in the past hour.
20 Mar 2013 - 0415 -- -- GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. Ash plume was not identifiable in multispectral satellite imagery; a bright hotspot was detected with infrared sensors; occasional bursts of seismic activity were reported; SIGMET reports ash to 5 km a.s.l. moving SE at 5 m/s.
20 Mar 2013 - 1015 -- -- GOES-13. GFS WINDS. Near summit emissions of gases and occasional light volcanic ash; although brilliant hot spot was readily apparent in satellite imagery, no ash was detected under partly cloudy conditions.
21 Mar 2013 - 1332 5.5 E 7.5 m/s GOES-13. GFS WINDS. Intermittent emissions; ash emissions and a persistent hotspot were observed in satellite imagery in clear skies; several discreet puffs were noted; ash plume extends ~32 km to the ESE of the volcano.
28 Mar 2013 - 1315 4.6 W 2.6 - 5 m/s GOES-13. INSIVUMEH. ECMWF HIRES WINDS. Continuous emissions; a series of emissions has resulted in an ash plume extending up to 18.5 km to the WSW of the summit.
30 Mar 2013 - 1415 5 S 8 m/s GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. INSIVUMEH reported degassing with occasional bursts of ash at 1240 UTC, 1330 UTC, and 1415 UTC; multibursts of gas and ash seen moving to S and SE from the summit extending 55.5 km from the summit and dispersing; light ashfall was reported within 18.5 km of the summit.
30 Mar 2013 - 1945; 5 S 2.6-5 m/s GOES-13. GFS WINDS. Ongoing emissions; satellite imagery showed a 20 km wide plume of light ash extending 13 km S of the summit; ash was expected to disperse within 6 hours.
31 Mar 2013 - 1345 -- -- GOES-13. GFS WINDS. INSIVUMEH. Ongoing emissions; ash not seen in satellite imagery under clear skies; however, sun may be preventing light ash from being observed; ash had been reported in the village of Panimaché.
31 Mar 2013 - 1945 -- -- GOES-13. GFS WINDS. INSIVUMEH. Continuous gas emissions with occasional short bursts of light ash; INSIVUMEH reported continued gas emissions with short bursts of light ash moving S; ashfall was reported within 9.3 km of the summit; ash not seen in satellite imagery due to cloud cover around the summit.

During 2011, INSIVUMEH reported that Fuego's activity included small-scale explosions and effusive lava flows. Lava flow activity was reported mainly during late March, late April, June, and early July. The longest lava flows traveled SW within the Ceniza and Santa Teresa drainages. Maximum flow lengths were in the range of 100-200 m and were frequently incandescent at night during spalling events.

Escalating summit activity during 2012. In early 2012, three VAAC advisories included plume altitudes as high as 6.7 km a.s.l. and drift directions up to 7.5 m/s S, SW, and W (table 8). INSIVUMEH reported that during the first week of January 2012, the Alert Level was raised to Yellow due to elevated activity; incandescent explosions were observed during 18-19 and 23 January. Lava flows and intermittent incandescent spatter continued from the summit throughout the rest of this reporting period (2011-March 2013).

The Coordinadora Nacional para la Reducción de Desastres (CONRED) announced Alert Level Orange (third highest on a four-color scale) and evacuations from El Porvenir in Alotenango (9 km ENE) on 19 May due to escalating activity (figure 21). Energetic Strombolian eruptions occurred during 19-20 and 25-27 May. Pyroclastic flows during 25-26 May were directed E and SE (impacting the Las Lajas and El Jute drainages), unlike previous events that concentrated flows within the W sector. Significant populations, resorts, and infrastructure such as the RN-14 road are located along the Las Lajas and El Jute drainages.

Figure (see Caption) Figure 21. A plot of the daily average RSAM (Real-time Seismic-Amplitude Measurement) from Fuego's seismic station FG3 during January through September 2012. Notable peaks include eruptions during 19-20, 26-27 May and 11 June; the effusive eruption of 1 July; the 3 September eruption, lahars, and lava flows; and the 13 September eruption. During this time period, seismicity was dominated by long-period (LP) earthquakes generated by processes such as explosions, fluid movement, lava flows, and block avalanches. Courtesy of INSIVUMEH.

During May-June, there were ~20 VAAC advisories that highlighted INSIVUMEH observations and the possibility of ash plumes; satellite observations and calculations of plume altitudes, however, were not available (table 8). INSIVUMEH reported lava flows throughout May-August (extending up to 1.7 km from the summit and as wide as 25 m) and pyroclastic flows occurred during May.

Increased explosivity at Fuego during September 2012. During the first week of September 2012, the Washington VAAC issued advisories describing ash plumes up to 5.2 km a.s.l. (table 8). A large event, on 3 September, generated two ash plumes dispersing SW and W, the former was ~5.5 km wide, and the latter was ~7.5 km wide. Ash plumes and hot spots continued to be visible within satellite images through 4 September (figure 19C) with INSIVUMEH reporting a lack of ash clouds on 5 September, followed by a break in reports until the major eruption on 13 September.

Beginning at 0400 on 13 September, a significant eruption occurred which led to evacuations from local communities within a 10-km radius (figures 22 and 23). At 0715, a vertical plume erupted from the summit. Large pyroclastic flows were generated between 0900 and 1000 local time which became channelized within two drainages. Within the Las Lajas drainage (on the SE flank), flows reached as far as 2 km from the summit; within the Ceniza drainage (SSW flank), they traveled as far as 7.7 km, stopping just 3 km short of Panimaché. On 14 September, the Washington VAAC reported ash plumes up to 7.3 km a.s.l. that drifted W at ~10 m/s (table 8).

Figure (see Caption) Figure 22. On 13 September 2012, a large plume of ash erupted from Fuego and pyroclastic flows descended the flanks. Between 0900 and 1000 local time, a lateral cloud and a tall plume expanded from the summit. The sharp peak to the right of Fuego is Agua volcano. This photo was taken from a viewpoint near the base of Pacaya volcano, ~30 km S of Guatemala City. Photo courtesy of Kent Caldwell.
Figure (see Caption) Figure 23. Comparison views of Fuego made from the city of Antigua (~18 km from Fuego) looking SW. (Top) This view from the center of Antigua, was taken on 21 March 2008 at 0915 when volcanic unrest was dominated by intermittent, impulsive eruptions which generated short gas-and-ash plumes (see figure 20 for the timeline of explosive vs. effusive activity). Photo courtesy of Kyle Brill (Michigan Technological University). (Bottom) This photo taken at ~0900 on 13 September 2012 captures a view SW of the ongoing explosive eruption that continued through 14 September. Photo courtesy of Luis Echeverria (Xinhua Press/Corbis).

In a special report by INSIVUMEH, the 13-14 September 2013 eruption was described as the largest explosive event within the last 13 years; they assigned the event VEI 3 (Volcanic Explosivity Index) based on the volume of pyroclastic material. This was the first eruption since 1974 that directly impacted the S and SW zones of Fuego, areas within 5-7 km of the summit that contained numerous small villages (figure 24). Approximately 10,600 people were evacuated from Panimaché I, Panimaché II, Sangre de Cristo, Morelia, and El Porvenir (figure 16) to the town of Santa Lucía Cotzumalguapa (18 km SW). INSIVUMEH estimated that ~5 mm of ashfall accumulated in those regions closest to the channelized pyroclastic flows. Ashfall damaged coffee and other agricultural crops in the region and congested the air, decreasing visibility in many communities within 10 km of the summit.

Figure (see Caption) Figure 24. Two hybrid graphics each merging a regional map and MODIS image centered on Fuego (at the red pushpin icon). (A) Results captured at 1030 local time showing a plume generated by the eruption covered approximately ~900 km2. (B) At 1330 local time, the ash plume covered approximately ~2,500 km2, with less density; 47 municipalities in seven departments were primarily affected. The ash extends off this graphic and later reached Chiapas, Mexico. Image modified from CATHALAC, 2012.

Prior to the eruption, there wsa a notable increase in LP seismicity and high-amplitude tremor that lasted for hours. INSIVUMEH seismic records became saturated between 0947 and 0949, the time period when observers noted ash plumes rising from the summit (figure 7). During the explosive event that began at 0400 on 13 September 2012, a lava flow advanced 300 m down the flank from the S side of the summit crater. At roughly the same time, a vertical plume rose from the crater and drifted SW; strong ENE winds rapidly spread the ash into the coastal Suchitepéquez Department. At 0715 the ash plume had risen up to 2 km above the summit crater; by 1500 that day, a diffuse ash plume was reported over the S region Mexico's Chiapas Province. The ash continued to expand W and NW on 14 September, and was ~100 km wide and more than 415 km W of the summit (table 8 and figure 10); ash persisted in the atmosphere for more than 36 hours.

Figure (see Caption) Figure 25. A large ash plume drifted W and NW from Fuego on 14 September 2012; observations were made at 0045, 0700; 1300; and 1900 local time and remote sensing measurements determined an altitude of ~7 km a.s.l. These graphics notified the aviation community about airspace containing ash plumes. Note that "VA to FL 240" means "volcanic ash to flight level 24,000 (~7 km)." Courtesy of Washington VAAC.

Seismicity and surface activity returned to low levels after the powerful 13-14 September 2012 eruption. Field studies conducted by INSIVUMEH determined that the Las Lajas, El Jute, Trinidad, and Ceniza drainages received the largest concentration of volcanic material during the eruption, making these regions susceptible to lahars with the onset of the rainy season.

Within the Ceniza drainage, in particular, pyroclastic flows had extended ~8 km (figures 17 and 26) and had deposited tree branches and trunks (many that were charred) within the canyon along with large (1-3 m diameter) blocks and volcanic bombs. Preliminary assessments of the deposits within the Ceniza drainage determined that ~13,000,000 m3 of material had been deposited and was already becoming mobilized.

Figure (see Caption) Figure 26. During field investigations immediately after the 13 September 2012 eruption, INSIVUMEH surveyed the Ceniza drainage to assess both the damage and potential new hazards from lahars. This area sits in the region of Siquinala and San Andrés Osuna, ~13 km SSW of Fuego's summit. Courtesy of INSIVUMEH.

Assessments by INSIVUMEH at the end of 2012 determined that two months of heavy rain had cut deep incisions into the new deposits and that loose, fine-grained volcaniclastic material had already migrated down to the road crossing at Siquinala and San Andrés Osuna, ~13 km SSW of the summit. The study also described the increased vulnerability of the road access for Siquinala and the community of La Róchela (figure 16) due to possible stream capture by Ceniza with Platanares. A narrow (~15 m) zone of the Ceniza drainage had been filled with volcaniclastic material, changing the drainage profile in a location ~2 km upstream from an important stream crossing. The Ceniza drainage had been migrating laterally toward the Platanares over time, especially due to erosion following Tropical Storm Agatha in 2010.

Explosive and effusive activity continued during September 2012-March 2013.From late September 2012 through March 2013, INSIVUMEH documented ash plumes (100-1,300 m above the crater), incandescent spatter (50-200 m above the crater), lava flows (mainly flowing 100-900 m down the SW flank), and lahars. In 2012, hot lahars were reported on 1 June, and later on 27 September and 3 October. Lava flows were frequently channelized within the Ceniza, Trinidad, and Taniluya drainages (SW flank). The last significant VAAC report of 2012 highlighted discreet puffs of ash that reached a maximum of 900 m above the crater on 29 September (table 8).

Large pyroclastic flows on 16 and 17 February 2013 traveled 3 km down the Ceniza drainage (table 8). Ash plumes generated on 16 February caused ashfall in communities up to 12 km from the summit, primarily SW. On 17 February there were collapses at lava-flow fronts.

On 4 March 2013 there were large lava flows following incandescent explosions up to 100 m above the crater (table 8).

On 19 March an explosive eruption occurred with effusive lava flows; a ~5 km a.s.l. ash plume was detected by the Washington VAAC (table 8). Lava fountaining reported on 20 March rose 300-400 above the crater; a ~1.5 km long lava flow within the Ceniza drainage was also observed that day (figure 19D). Incandescent explosions were frequently observed through the rest of the month.

International collaboration aids monitoring capabilities in 2013. In 2010, a partnership was established between INSIVUMEH observatories and the International Volcano Monitoring Fund (IVM-Fund), a non-profit organization based in Seattle, WA. After a successful project to improve monitoring efforts at the Santiaguito Volcano Observatory (OVSAN), the IVM-Fund began working with the Fuego Volcano Observatory (OVFGO), located in Panimaché, in 2012. During March 2013, this observatory received significant support from the IVM-Fund and international donors. Jeff Witter, president and CEO of the IVM-Fund, delivered ~$4,500 worth of field equipment to OVFGO to help outfit the observers and contribute to volcano monitoring capacity in Guatemala (figure 27). Additional visits to Guatemala are planned once sufficient funds are raised to continue the IVM-Fund's collaborative work with Guatemalan volcanologists. Volcano monitoring support projects between the IVM-Fund and INSIVUMEH are planned to address additional needs at OVFGO and OVSAN.

Figure (see Caption) Figure 27. On 21 March 2013, INSIVUMEH technician Amilcar Cardenas (left) and Edgar Barrios (far side of river) measure the width of Taniluya drainage to collect baseline data for monitoring geomorphologic changes in the canyon. This drainage is particularly susceptible to lahars and pyroclastic flows. Courtesy of Jeff Witter (IVM-Fund).

References. CATHALAC, 2012, "Preliminary Analysis of the Eruption of Volcan de Fuego, Guatemala -- 13 September 2012," posted on 27 September 2012, https://servirglobal.net/Global/Articles/tabid/86/Article/1169/preliminary-analysis-of-the-eruption-of-volcan-de-fuego-guatemala-13-september.aspx, accessed on 17 July 2013.

Escobar-Wolf, R., 2013, Volcanic processes and human exposure as elements to build a risk model for Volcán de Fuego, Guatemala [PhD Dissertation]: Houghton, MI, Michigan Technological University.

Newhall, C.G., and Self, S., 1982, The volcanic explosivity index (VEI): An estimate of explosive magnitude for historical volcanism, Journal of Geophysical Research: 87, 1231-1238.

The World Bank, 2013, Country Data: Guatemala Climate Change, http://data.worldbank.org/country/guatemala, accessed on 18 June 2013.

Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Information Contacts: Gustavo Chigna M., Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), Ministero de Communicaciones, Transporto, Obras Públicas y Vivienda, 7a. Av. 14-57, zona 13, Guatemala City 01013, Guatemala (URL: http://www.insivumeh.gob.gt/inicio.html); Coordinadora Nacional para la Reducción de Desastres (CONRED), Av. Hincapié 21-72, Zona 13, Guatemala City, Guatemala (URL: http://conred.gob.gt/www); Washington Volcanic Ash Advisory Center (VAAC), NOAA Science Center Room 401, 5200 Auth road, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); Rüdiger Escobar-Wolf, Michigan Technological University, Department of Geological and Mining Engineering and Science, Houghton, MI, USA (URL: http://www.geo.mtu.edu/); Hawai`i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System (MODVOLC), School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai`i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Jeff Witter, International Volcano Monitoring Fund (IVMF) (URL: http://www.ivm-fund.org/guatemala-fuego/); NASA/USGS Landsat Program (URL: https://landsat.usgs.gov/); and NASA ALI (URL: http://eo1.gsfc.nasa.gov/).


Gaua (Vanuatu) — May 2013 Citation iconCite this Report

Gaua

Vanuatu

14.27°S, 167.5°E; summit elev. 797 m

All times are local (unless otherwise noted)


Hazard status raised; emissions continue into 2013; plume observed from above

In our June 2012 Bulletin report (BGVN 37:06), we noted ongoing eruptions from Gaua during much of 2011.

On 5 December 2011, the Vanuatu Meteorology and Geohazards Department (VMGD) changed the status of Gaua volcano from a dormant to an active volcano. An index map showing Vanautu appears in the Ambrym report in this issue.

The Wellington Volcanic Ash Advisory Center (VAAC) reported that on 29 April 2013 a plume from Gaua was observed from an aircraft. Absent were further comments. Satellite imagery did not indicate ash. Astronauts on the International Space Station saw and photographed Gaua's E-blowing plume on 31 May 2013 (figure 24).

Figure (see Caption) Figure 24. Steam plume from Gaua volcano as photographed from the International Space Station on 31 May 2013. For scale, the island is 20 km in diameter. Note N arrow at lower right. This is Astronaut photograph ISS036-E-5647, taken on Expedition 36 with a Nikon D3S digital camera using a 400 mm lens, and is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Laboratory, Johnson Space Center. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Original caption was by William L. Stefanov, Jacobs/JETS at NASA-JSC.

The Alert Level of Gaua remained at level 1 (out of 4) signifying that changes in Gaua's activity could occur without, or with little, warning. VMGD continued this status through at least mid-August 2013, although they noted as slight increase in tremor since their June report.

This status indicates that ash falls will continue to be expected in areas exposed to trade winds. Strong degassing of the volcano could be accompanied with acid rainfall.

During the year ending in mid-July 2013, there were no MODVOLC thermal alerts.

Geologic Background. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank in 1962 ended a long period of dormancy.

Information Contacts: Vanuatu Geohazards Observatory (URL: http://www.vmgd.gov.vu/vmgd/); Vanuatu Meteorology and Geohazards Department (URL: http:// http://www.meteo.gov.vu/); Wellington Volcanic Ash Advisory Center (VAAC) (URL: vaac.metservice.com); and Hawai'i Institute of Geophysics and Planetology, MODVOLC Thermal Alert System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i , 2525 Correa Road, Honolulu, HI 96822 USA (URL: http://modis.higp.hawaii.edu/).


Kilauea (United States) — May 2013 Citation iconCite this Report

Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)


Summary of highlights for 2010-2012

The following is a concise summary of reports by the U.S. Geological Survey-Hawaiian Volcano Observatory (HVO) on Kilauea volcano covering the 3 years 2010-2012. Volcano highlights for 2009 were covered in BGVN 38:02.

Figure 209 shows a map of the lava-flow field on Kilauea's east rift zone as of 26 July 2013. On this map some of the older lava flows are labeled with the years during which they were active. Other maps appearing in earlier Bulletin reports indicated important features such as Napau crater, Pu'u 'O'o. HVO posts both Daily and Weekly updates on Kilauea activity (at links provided in the Information Contacts section below).

Figure (see Caption) Figure 209. Small-scale map showing Kilauea's east rift zone flow field as of 26 July 2013. The Peace Day flow, carried lava from the vent area to the ocean, and the inactive Kahauale'a flow from early 2013, are light reddish orange and labeled "2011-2013.". The active flow called Kahauale'a 2 flow N of Pu'u 'O'o, is shown in shades of red, with bright red showing expanded coverage since June 2011. Older lava flows are labeled with the years in which they were active. Flows during 1983-1986 (episodes 1-48b) are shown in gray; during 1986-1992 (episodes 48c-49) in pale yellow; during 1992-2007 (episode 50-55) in tan; and during 2007-2011 (episodes 58-60) in pale orange. The location of the Peace Day lava tube is shown by the yellow line, but where the tube crosses the coastal plain it has not been mapped. The interval between the contours depicting the topographic high at Pu'u 'O'o is 5 m. Courtesy of USGS/HVO.

The Hawaiian Volcano Observatory (HVO) celebrated its centennial in January 2012 and the 30th year of Kilauea's ongoing eruption, now active at its summit and east rift zone, on 3 January 2013.

Orr and others (2012) summarized Kilauea's 30-year-long eruption, furnishing the following excerpt from the 2010-2012 period in that report.

Summary of 2010-2012. Regarding this interval, Orr and others (2012) made the following comments. "In January 2010 . . . the tube system broke down [enabling lava to escape from the tube] and surface flows began moving toward the east, encroaching on the Kalapana area once again. Three more houses were destroyed between July 2010 and March 2011, when the surface flows faltered.

"2011-2013: History Repeats Itself.

"Pu'u 'O'o began to refill slowly during 2010, and by early March 2011, the crater floor was within 65 feet (20 meters) of the crater's east rim. On March 5, 2011, following rapid summit deflation and increased seismicity, the crater floor of Pu'u 'O'o collapsed. Within a few hours, it had dropped 380 feet (115 meters). Shortly thereafter, lava broke to the surface between Pu'u 'O'o and Napau Crater, marking the start of the Kamoamoa fissure eruption, which was active through March 9. Reminiscent of Kilauea's 1997 and 2007 East Rift Zone fissure eruptions, the Kamoamoa eruption cut the lava supply to the active tube, causing activity on the flow field to die.

"After 2 weeks of quiet, lava reappeared in Pu'u 'O'o on March 26, and a perched lava lake developed as the crater refilled. In late June, wholesale uplift of the crater floor raised the entire lava lake until its surface was higher than the eastern and western crater rims. Leaks from the "ring" fault bounding the uplifted area resulted in lava overflowing the crater for the first time since 2004, sending flows down the southwestern flank of Pu'u 'O'o. {Note that this is discussed further below.}

"On August 3, 2011, the crater floor of Pu'u 'O'o collapsed again when lava burst through Pu'u 'O'o's west flank, burying the western base of the cone in a massive flood of lava. The floor of the crater dropped 260 feet (80 meters), accompanied by the collapse of large slabs of rock from the crater walls into the resulting pit. The flow on the west side of Pu'u 'O'o diminished greatly after the first several hours but remained active until August 15.

"As in March, lava returned to Pu'u 'O'o within days of the August outbreak, but this time the crater filled quickly. By September 10, lava had begun to overflow the crater again, with flows spilling toward the northeast and southwest. This activity ended on September 21, when the northeastern flank of the cone fractured and lava began pouring out.

"Confined to a shallow valley between older Pu'u 'O'o flow fields, lava turned again toward the volcano's S coast. In March 2012, lava flows destroyed another house-the 214th since 1983-within the now-abandoned Royal Gardens subdivision {approximate location shown in figure 209}.

"Unlike past years, however, eruptive activity throughout 2012 was relatively weak. Lava flows were almost always active on the coastal flow field but failed to make significant forward progress. Finally, in late November, lava reached the coastline for the first time in nearly 11 months, forming a small and sporadic ocean entry. This marked the end to the longest period without an ocean entry since lava first reached the water in 1986.

"As the eruption enters its 31st year in 2013, it is showing no signs of stopping, despite the recent slow down in activity. What Kilauea Volcano has in store next remains to be seen. Although recent patterns suggest continued activity on the East Rift Zone, this could change abruptly. Even a return to Kilauea's more explosive past is possible (see USGS Fact Sheet 2011-3064, Kilauea-an Explosive Volcano in Hawai'i, available at http://pubs.usgs.gov/fs/2011/3064 {Swanson and others, 2011}). What is certain is that Kilauea will remain an active volcano for millennia to come."

More details on 2010-2012 events. HVO reporting disclosed events presented below (tables 6-8), including a brief summary of 2010-2012 events (table 5), a broad overview of the eruption during 2007-2012 (table 6), and several of the notable collapses during 2010-2011 (table 7).

Table 6. Brief summary of events at Kilauea during the period 2010-2012. Courtesy of various USGS/HVO reports (periodic, fact sheets, etc.).

Date(s) Event
04 Jan 2010 Cessation of Waikupanaha ocean entry after 22 months
25 Jan-10 Mar 2010 Persistent flow through Royal Gardens and out onto the coastal plain
Feb or Mar 2010 Small collapse of E wall Pu'u 'O'o crater rim
29 Apr-30 Nov 2010 New ocean entries of lava at Ki, Puhi-o-Kalaikini, and 'Ili'ili
May, Jul, and Aug 2010 Portions of N rim of Pu'u 'O'o fall into crater
May-Jun 2010 Lava erupted on S wall and NE side of Pu'u 'O'o crater
Late July, 27 Nov 2010 2 houses destroyed in Kalapana Gardens subdivision
Sep-Dec 2010 Eruption of vent on W edge of Pu'u 'O'o crater
Nov 2010-Feb 2011 Increase in long-term inflation of Pu'u 'O'o crater
2011 East rift zone eruption episodes 58-61 (see Table 6)
Jan, early Feb 2011 Ocean entries at 2 previous areas, Puhi-o-Kalaikini and Ki
17 Feb 2011 House destroyed in Kalapana Gardens subdivision
05 Mar 2011 Beginning of eruption Episode 59 (see table 6); floor of Pu'u 'Æ crater began collapsing; new fissures opened between Napau Crater and Pu'u 'O'o
26 Mar 2011 Beginning of eruption Episode 60 (see table 6); lava filled collapse crater of Pu'u 'O'o and uplifted lake floor
24 July 2011 Lava flow from ring fracture along SW margins of Pu'u 'O'o crater
03 Aug 2011 Lava lake draining through from lower W flank of Pu'u 'O'o; lake completely drained within several hours, leaving a rubble-filled depression ~80 m below its pre-collapse level
20 Aug 2011 Beginning of eruption Episode 61; Pu'u 'O'o refilled and overflowed
21 Sep 2011 Lava broke through the upper E flank of the Pu'u 'O'o cone; Pu'u 'O'o crater subsided ~20 m; flow (Peace Day flow) resulted in a channelized 'a'a' flow to SW
22 Sep 2011 Channelized 'a'a' flow stalled; fissure and open channel crusted over by mid-Oct 2011
09 Dec 2011 Flow reached ocean entry by evening 9 Dec 2011
2012 Peace Day flow continued to be active
Early 2012 Subsidence in Pu'u 'O'o crater continued; outgassing events on crater floor
02 Mar 2012 House in Royal Gardens subdivision destroyed
End of Aug 2012 Deflation phase led to lowering of lava lake beneath Pu'u 'O'o crater ; lava began erupting and filled in NW pit by Sep 2012.

Table 7. An overview of the Kilauea East Rift Zone (ERZ) eruption during 2007-2012 (eruption episodes 57-61) including (from left) episodes, dates, (approximate in some cases) vent locations, and estimated volume of erupted material. HVO subdivides 30-year-long Pu`u `O`o eruption into episodes. Each new episode denotes vigorous new eruptive activity either from a different vent or commencing after a pause or slowdown. Some episodes are well defined; others more arbitrary. The day and time of various episodes may vary slightly with different instrumentation. The dates in the table signify the duration of the episode or episodes. Courtesy of M. Patrick (USGS) and various USGS/HVO reports.

Dates Episode(s) Vent location Est. volume (km3)
1 Jul 2007-5 Mar 2011 57-58 Crater fill and fissures E of Pu'u 'O'o 0.63
05 Mar-09 Mar 2011 59 Kamoamoa fissures 0.003
26 Mar-15 Aug 2011 60 Pu'u 'O'o overflows and W flank vent 0.04
20 Aug 2011-present 61 Pu'u 'O'o overflows and Peace Day flow 0.15

Table 8. For Kilauea, a list containing several notable collapses and/or explosive events during 2010-2011. Courtesy of various USGS/HVO reports and Matthew Patrick, USGS/HVO.

Date Time (HST) Notes
11 Feb 2010 1551 Collapse in vent; continuous lava lake started
26 Apr 2010 1409 Collapse in vent; lava lake doubled in size
17 Jan 2011 2311 Series of explosions
21 Jan 2011 1430 Explosion
14 Feb 2011 0908 Series of explosions
15 Feb 2011 0305 Series of explosions
20 Feb 2011 0049 Explosion
03 Mar 2011 1236 Series of explosions
21 Dec 2011 1655 Explosion

30-year long eruption summary comments. Table 9 and figure 210 present general information about the total 30-yr eruption period.

Table 9. Selected eruption statistics for the entire 30-year during 1983 to January 2013. Courtesy of Orr and others (2013) and various USGS/HVO reports.

Feature Statistic
Area covered 125.5 km2
New land on coast 2.02 km2
Volume erupted (dense rock equivalent) ~4 km3
Thickness along coast 10 to 35 m
Pre-1983 area covered in 2012 0.4 km2
Net total of land added to the island (Nov 1986–Dec 2012) 2.015 km2
Coastal highway covered by lava 14.3 km
Structures destroyed 214
Pu'u 'O'o maximum height 255 m in 1987; 171 m in 2012
Pu'u 'O'o crater size 300-450 m

Satellite images. To provide a comparison, NASA Earth Observatory prepared both a natural-color satellite image from 6 June 2011 (figure 210a), and a black-and-white aerial photograph from 25 March 1977 (figure 210b). As the authors noted, the images both show the landscape surrounding Napau Crater and Pu'u 'O'o. Lava flows that are more than a century old are covered by a dense forest of ohia lehua and tree ferns forest (green in the 2011 image). Flows from eruptions in 1965, 1968, and 1969 are much lighter than the forest in the 1977 image, but difficult to differentiate from one another. By comparison, the 2011 image shows profound changes in the landscape.

Weathered lava from the initial Napau Crater vent is almost indistinguishable from the older (1968 and 1969) lavas that cover most of the crater floor. In January 1997, a fresh line of fissures opened within Napau Crater, erupting lava during Episode 54 of the Pu'u 'O'o-Kupaianaha eruption. Additional cracks and fissures split the earth between Napau Crater and Pu'u 'O'o in the March 2011 Kamoamoa Fissure Eruption (Episode 59), spreading black lava through the forest. Scorched forest appears reddish-brown along the edges of the lava flows. Since 9 March 2011, lava flows have originated from Pu'u 'O'o(figure 210a, upper right). A lava pond is visible within the crater, and a system of lava tubes carries molten rock underground to the southeast. Brown lavas surrounding the crater flowed directly from the lava pond.

Figure (see Caption) Figure 210. Two images-a natural-color satellite image from June 6, 2011 (A), and a black-and-white aerial photograph from March 25 (B), 1977-show the landscape surrounding Napau Crater and Pu'u 'O'o. Lavas of different ages cover the surface. Lava flows that are more than a century old are covered by a dense forest (green in the 2011 image) of ohia lehua and tree ferns. Flows from eruptions in 1965, 1968, and 1969 are much lighter than the forest in the 1977 image, but difficult to differentiate from one another. The 2011 image shows dramatic changes in the landscape. Weathered lava from the initial Napau Crater vent is almost indistinguishable from the older (1968 and 1969) lavas that cover most of the crater floor. In January 1997, a fresh line of fissures opened within Napau Crater, erupting lava during episode 54 of the Pu'u 'O'o-Kupaianaha eruption. Additional cracks and fissures split the earth between Napau Crater and Pu'u 'O'o in the March 2011 Kamoamoa Fissure Eruption (Episode 59), spreading black lava through the forest. Scorched forest appears reddish-brown along the edges of the lava flows. Since 9 March 2011, lava flows have originated from Pu'u 'O'o (image upper right). A lava pond is visible within the crater, and a system of lava tubes carries molten rock underground to the southeast. Brown lavas surrounding the crater flowed directly from the lava pond. Images taken from Simmon (2012).

References. Orr, T., Heliker, C., and Patrick, M., 2012, The ongoing Pu'u'O'o eruption of Kilauea Volcano, Hawai'i-30 years of eruptive activity, U.S. Geological Survey Fact Sheet 2012-3127, 6 p. (URL: http://pubs.usgs.gov/fs/2012/3127/; accessed 15 August 2013).

Simmon, R., 2012, 30th Anniversary of the Pu'u 'O'o Eruption on Kilauea, NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=80091).

Swanson, D., Fiske, D., Rose, T., Houghton, B, and Mastin, L., 2011, Kilauea-an explosive volcano in Hawai'i, U.S. Geological Survey Fact Sheet 2011-3064, 4 p (URL: http://pubs.usgs.gov/fs/2011/3064/; accessed 15 August 2013).

USGS/HVO, 2012, Kilauea's east rift zone (Pu'u 'O'o) eruption 1983 to present, 13 April 2012, 14 p. (URL: http://hvo.wr.usgs.gov/kilauea/summary/#Mar2011; accessed 15 August 2013).

USGS/HVO, 2013, Maps, July 26, 2013 - Kilauea, Kilauea's east rift zone flow field, web site (URL: http://www.wr.usgs.gov/maps; accessed 15 August 2013).

Geologic Background. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.

Information Contacts: Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawai'i National Park, HI 96718, USA (URL: https://volcanoes.usgs.gov/observatories/hvo/, Daily updates, https://volcanoes.usgs.gov/observatories/hvo/activity/kilaueastatus.php, and Weekly updates, https://volcanoes.usgs.gov/observatories/hvo/volcanowatch/).


Pavlof (United States) — May 2013 Citation iconCite this Report

Pavlof

United States

55.417°N, 161.894°W; summit elev. 2493 m

All times are local (unless otherwise noted)


Eruption in May-June 2013 with lava flows and ash emissions to ~8.5 km a.s.l.

Pavlof, the most active volcano in the Aleutian arc, erupted on 13 May 2013. Before this, it had most recently erupted on 15 August 2007, following an 11-year period of quiescence. The eruption that began in May 2013 continued through June before slowly subsiding to background levels by 8 August. Pavlof generated several ash plumes during the six-week eruption that disrupted aviation, including an 8-km high plume on 24 June. As in past Pavlof eruptions, the recent eruptions fluctuated in intensity. This report briefly discusses earthquake data during 2007-2011 and, in greater detail, the series of eruptions during May and June 2013.

According to Mangan and others (2009), Pavlof has discharged more than 40 recorded eruptions within the previous 200 years, producing mostly basaltic andesite to andesite products. That work, discussed in a separate subsection near the end of this report, also discusses the adjacent 12x19 km Emmons Lake caldera (a chain of nested calderas) on Pavlof's SW flank (figure 5). The Emmons Lake Volcanic Center (ELCV) is used to collectively describe the entire complex, including the nested caldera, intra-caldera stratovolcanoes, and the adjacent stratovolcanoes (including Pavlof) to the NE.

Figure (see Caption) Figure 5. Maps showing both the location of Pavlof on the lower Alaska Peninsula (upper left) and showing more details of the complex, including the elongate Emmons Lake caldera and six stratovolcanoes. The lake occupies but a small volume of the caldera, which is breached to the SE. Taken from Mangan and others (2009).

According to the Alaska Volcano Observatory (AVO), 48 earthquakes were located beneath Pavlof in 2007, the year of the previous eruption. During the following non-eruptive years, AVO reported 9 earthquakes centered at Pavlof in 2008, 7 earthquakes in 2009, 19 in 2010, and 13 in 2011. As of this writing, AVO has not yet published 2012 earthquake data.

Eruption in May 2013. On 13 May 2013, seismicity increased at 0800 and an intense thermal anomaly was observed at the summit in satellite imagery. Several spikes in seismicity occurred between 0900 and 1000. AVO noted that similar patterns of seismicity and elevated surface temperatures in previous cases had signaled the onset of eruptive activity at Pavlof. The Volcanic Alert Level was increased to Watch (the second highest category of four) and the Aviation Color Code was increased to Orange (the second highest category of four).

On 14 May 2013, pilot reports and satellite images indicated a spatter-fed lava flow that had advanced about 0.5 km down the N flank. The advancing lava had also generated debris-laden deposits, presumably from the interaction of hot lava with snow and ice on the flank. According to AVO, a diffuse ash plume drifted about 160 km NE at an altitude of 4.6 km before dissipating. Minor ashfall was reported the evening of 14 May in a mining camp 80 km NE of the volcano. No other nearby communities reported ashfall. Minor steam-and-ash emissions from the summit were visible from Cold Bay (~58 km SW).

During 14-15 May 2013, elevated seismicity persisted. Steam-and-ash clouds observed with a web camera at Cold Bay (55 km W of the volcano) occasionally rose to an altitude of 6.1 km. Residents in Cold Bay observed incandescence from the summit during the night. On 15 May a pilot reported a dark ash cloud drifting ENE at an altitude of 6.1 km.

On 16 May, AVO observed lava fountaining at the summit and a continuous ash, steam, and gas cloud extending 50-100 km downwind at an altitude of about 6.1 km. Satellite images showed persistent elevated surface temperatures at the summit and on the NW flank, consistent with lava fountaining at the summit and the resulting lava flow.

During 18-19 May 2013, reports noted that a narrow plume of steam, ash, and gas occasionally rising up to an altitude of 6.7 km and drifting SE was visible in satellite and pilot images (figures 6 and 7). Pilots noted that lava fountaining and ash emission continued. Overnight, trace amounts of ash fell on the community of Sand Point (88 km E). During the afternoon on 19 May, pilots reported that ash plumes rose to altitudes of 4.6-6.7 km. Trace amounts of ash fell in Nelson Lagoon (78 km NNE) during 19-20 May.

Figure (see Caption) Figure 6. Photograph of Pavlof taken on 18 May 2013 by astronauts aboard the International Space Station. The space station was ~770 km away and S-SE of the volcano when the photograph was taken. The volcanic plume extended SE over the North Pacific Ocean. Residing next to Pavlof is the white, seemingly ash free stratovolcano Pavlof Sister. Courtesy of NASA Earth Observatory with credit for caption and processing to Robert Simmon, (NASA Earth Observatory) and G. M. Gentry (DB Consulting Group at NASA-JSC).
Figure (see Caption) Figure 7. Photo of Pavlof eruption taken by a commercial pilot on 18 May 2013. Plume direction was not identified, but based on the NASA photo taken the same day (figure 6), the plume is drifting SE and the volcano in the foreground is Pavlof Sister (NE of Pavlof). Courtesy of Brandon Wilson (PenAir) and provided by AVO/Alaska Division of Geological & Geophysical Surveys.

News articles (Associated Press, PRNewswire, Alaska Dispatch) stated that during 19-21 May 2013 two regional airlines canceled flights to several remote communities and delayed or re-routed other flights. On 21 May AVO reported that a low-level plume of steam, gas, and ash occasionally rose to an altitude of 6.1 km and drifted NNE. Trace amounts of ash again fell in Nelson Lagoon.

AVO reported that seismic tremor markedly declined around 1100 on 21 May 2013 and was followed through 23 May by the detection of small discrete events, likely indicative of small explosions, by an infrasonic pressure sensor (Chaparral model 2.5 at site PN7). Although cloud cover prevented satellite observations, elevated surface temperatures at the vent were detected. On 22 May a pilot report and photographs indicated weak steam-and-gas emissions containing little to no ash.

The eruption continued at a lower level during 24-26 May. Neither evidence of elevated surface temperatures nor a plume were observed in partly clear satellite images during 24-25 and 27 May. Clouds obscured views on 26 May. The Volcanic Alert Level was lowered to Advisory and the Aviation Color Code was lowered to Yellow on 28 May.

According to AVO, Pavlof emitted ash on 4 June at about 1100, as observed in satellite images and by pilots. Satellite images showed an ash cloud drifting SE, and pilots estimated that the cloud was at an altitude of 5.8 km. Weak seismicity that began at 1057 accompanied the emissions, and then continued. AVO increased the Volcanic Alert Level to Watch and increased the Aviation Color Code to Orange.

AVO reported that ash emissions continued during 5-11 June 2013, accompanied by tremor and explosion signals. Overnight during 4-8 June, satellite images detected elevated surface temperatures near the vent consistent with lava effusion and fountaining. Elevated surface temperatures persisted until 14 June. On 5 and 6 June, an ash plume drifted 40-45 km W and SW at altitudes of 4.3-5.5 km based on pilot estimates. During 8-10 June, an ash plume drifted 20-53 km SE. During 12-14 June, ash emissions were intermittent and minor; ash plumes remained below an altitude of 6.1 km and mostly drifted SE.

During 14-15 June 2013, seismicity decreased. Minor emissions probably ceased, but web-camera views were partially obscured by clouds. On 17 June no plumes were visible in satellite images, and web camera views showed mostly cloudy conditions.

During 17-18 June, tremor amplitude increased slightly, and elevated surface temperatures were again detected in satellite images. A small ash plume rose from the crater. The eruption continued during 19-25 June, with tremor and occasional explosions. Cloud cover prevented web camera views. Elevated surface temperatures continued to be detected during 19-20 and 24 June. A small ash plume from the summit vent was also detected in a satellite image on 19 June, and possibly during 20-22 June.

On 24 June, seismicity increased to the strongest level to date during 2013 and included continuous intense tremor and frequent small explosions likely associated with lava fountaining and ash production. Seismicity remained high on 25 June. Satellite images and pilot observations indicated that a plume drifted W at altitudes as high as 8.2-8.5 km. Satellite images also detected a strong thermal anomaly at the summit. Trace amounts of ash fell in King Cove (48 km SW). According to a news report (Reuters), regional air traffic was again cancelled or re-routed.

According to AVO, seismicity declined during 25-26 June and consisted of intermittent bursts of tremor and occasional small explosions. Satellite images showed a plume containing small amounts of ash drifting NW, and strong thermal anomalies at the summit. Pilot reports on 26 June indicated that plumes rose to altitudes between 6.1-7.6 km during the morning and then to heights just above the summit later that day. Seismicity during 26 June-1 July continued at low levels and consisted primarily of intervals of continuous, low-level tremor. Thermal anomalies at the summit detected in satellite images were strong during 26-29 June and weak during 30 June-1 July.

AVO reported that activity further declined during 1-2 July; tremor and explosions were no longer detected in seismic and pressure sensor data. Satellite images did not detect elevated surface temperatures, volcanic gas, or ash emissions, and there were no visual observations from pilots or from webcam images of any eruptive activity since 26 June. Consequently, AVO lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory.

On 8 August, AVO reported that no lava or ash emissions had been observed at Pavlof since 26 June and the volcano had exhibited gradually declining levels of unrest. Seismicity was at background levels. Thus, AVO lowered the Aviation Color Code to Green and the Volcano Alert Level to Normal.

Mangan and others (2009) discussion. Mangan and others (2009) cite Power and others (2004) as stating that background (non-eruptive) seismicity at Pavlof occurs as infrequent long-period earthquakes at focal depths between 20-40 km. Mangan and others contend that while only a few of these events at most occur annually, they are a stable feature attributed to quasi-steady fluxing of basaltic magma and exsolved CO2 in a deep dike and sill complex. According to the article, the seismic network at Pavlof is poorly situated to detect deep seismicity under the Emmons Lake caldera.

Mangan and others state, "All witnessed [Emmons Lake Volcanic Center] ELVC eruptions have occurred outside the caldera [,specifically] at Pavlof, the most active volcano in the entire arc. Pavlof's slopes are extensively mantled with tephra and pyroclastic debris produced during [its] historical strombolian, vulcanian, and lava fountain events (Miller et al., 1998). Limited precursory seismicity herald Pavlof eruptions (McNutt, 1989) and, to the extent studied, negligible precursory ground deformation (Lu et al., 2003; Z. Lu personal communication 2008). Of the 20 eruptions occurring since the installation of Pavlof's seismic network (1973), 13 eruptions have occurred with less than 24 h of warning. Pavlof is essentially an "open vent" volcano with magma rising aseismically through a thermally well-groomed conduit. High-frequency volcano-tectonic earthquakes, characteristic of magma rise through brittle crust, are virtually absent."

Figure 8 presents Mangan and others (2009) conceptualization of the plumbing beneath the ELVC, which includes Pavlof.

Figure (see Caption) Figure 8. Conceptual cross-section through the Emmons Lake Volcanic Center looking at a vertical plane parallel to the volcanic axis. The drawing shows two distinct plumbing systems drawing from a common magmatic source at more than 20 km depth. Courtesy of Mangan and others (2009).

The other volcano of the ELVC considered to have high likelihood of eruption is Mt. Hague (Waythomas and others, 2006). That study also presents a set of hazard maps for the complex.

References. Mangan, M., Miller, T., Waythomas, C., Trusdell, F., Calvert, A., and Layer, P., 2009, Diverse lavas from closely spaced volcanoes drawing from a common parent: Emmons Lake Volcanic Center, Eastern Aleutian Arc, Earth and Planetary Science Letters, Vol. 287, pp. 363-372.

Waythomas, CF; Miller, TP, and Mangan, MT, 2006, Preliminary Volcano Hazard Assessment for the Emmons Lake Volcanic Center, Alaska, U.S. Geological Survey Scientific Investigations Report 2006-5248 (URL: http://pubs.usgs.gov/sir/2006/5248/).

Geologic Background. The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a)U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: http://www.avo.alaska.edu/), b)Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c)Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://www.dggs.alaska.gov/); Associated Press (URL: http://www.ap.org/); PRNewswire (URL: http://www.prnewswire.com); Alaska Dispatch (URL: http://www.alaskadispatch.com/); and Reuters (URL: http://www.reuters.com/).


Veniaminof (United States) — May 2013 Citation iconCite this Report

Veniaminof

United States

56.17°N, 159.38°W; summit elev. 2507 m

All times are local (unless otherwise noted)


Ongoing sporadic eruptions as late as 6 October 2013

In our last report on Veniaminof (figure 12) (BGVN 33:05), we noted that on 22 February 2008 several minor ash bursts had occurred, a process common in ten's of Bulletin and predecessor Smithsonian reports going back to 1983 (SEAN 08:05). In this report we provide a brief summary of activity from 1 March 2008 into October 2013, an interval including several episodes with lava flows, ash bursts, elevated seismicity, and ash fall. During 4 May 2008-7 June 2013 the available data suggest comparative quite, although during part of that time the volcano lacked a seismic monitoring system. During the reporting interval, the Aviation Alert Level often shifted between Orange and Yellow (high to intermediate values on a scale from Green to Red). As discussed below, there was also an interval without seismic monitoring announced 17 November 2009 when the hazard status was termed 'unassigned' owing to a seismic instrument outage. This report omits detailed seismic data published by the USGS (eg. Dixon and Stilher, 2009; Dixon and others, 2012). On 30 August 2013 ash plumes rose to over 6 km altitude.

Figure (see Caption) Figure 12. Location of Veniaminof on the Alaskan Peninsula. Map courtesy of AVO.

Table 1 synthesizes available AVO reporting on Veniaminof behavior during February 2008 through 6 October 2013. See their reports for more details. During the interval 4 May 2008 to 7 June 2013 the volcano was often quietly steaming, although seismicity increased during part of May 2009. Several highlights follow. Weather permitting, satellite images showed some days with high elevated surface temperatures at the cinder cone inside the caldera consistent with lava effusion. For example, during 24 July-30 July 2013, a "river of lava" flowed down the cone. As discussed in a subsection below, several noteworthy images were acquired in mid-2013 showing ash and thermal signatures on the volcano. On 30 August 2013 the plume reached over 6 km altitude as an unusually vigorous eruptive event ensued. The last lava emissions of the reporting interval took place on 6 October 2013.

Table 1. Representative dates and noteworthy eruptive or non-eruptive intervals at Veniaminof during March 2008 through late August 2013. Courtesy of AVO.

Date Ash plume altitude and movement Other comments
Late Feb through May 2008 Below 2.7 km Sporadic increases in seismic and eruptive activity were noted since 11 February, including tremor episodes that lasted 1-2 minutes and occurred several times per hour. Broadly during late February 2008, AVO noted both small ash bursts with local ashfall at the crater accompanied by seismicity, and occasional high thermal fluxes.
4 May 2008-7 June 2013 (Steaming) 7-26 May 2009, often quiet steaming with generally low to occasional high seismicity and with absence of thermal anomalies. No reports during other portions of the interval 4 May 2008 to 7 June 2013. Seismic station outage announced 17 November 2009, with seismic reports returning 8 June 2013.
19 June 2013 4.6 km NE Cloudy weather sometimes prevented views of the caldera, although most days satellite images showed very high elevated surface temperatures at the cinder cone inside the caldera consistent with lava effusion. On 19 June, residents in Sandy River reported ash bursts.
24-30 July 2013 4.5 km NW Lava effusion, a "river of lava," flowing down the cone.
14-20 August 2013 3.7 km W and then SSE AVO reported that during 13-15 August seismic tremor at Veniaminof was high, and persistent elevated surface temperatures consistent with lava effusion were visible on satellite imagery. An 18 August webcamera image revealed minor ash emissions. On 19 August a helicopter overflight revealed two lava flows On 20 August, trace ash fall reported in Perryville ((32 km SSE); they also heard hearing explosions; infrasound equipment in Dillingham (322 km NE) also detected impulses.
21 Aug-20 Oct 2013 4.6-6.7 km SE 27-29 Aug, episodic tremor bursts interpreted as lava effusion and emissions; prominent satellite thermal anomalies. On 30 Aug, some of the strongest emissions since the eruption began in June 2013; ongoing into early Sept but diminishing in late Sept, and without evidence of eruption in satellite and webcamera data on and around 20 Sept. A lava effusion was recognized 6 October, then waning by mid-October.

As noted above and in table 1, non-eruptive steaming prevailed at the volcano during much or all of the interval 4 May 2008-7 May 2009. On 17 November 2009 AVO announced that Veniaminof was one of four volcanoes in Alaska that they could no longer monitor because of seismic station outages. They then shifted both their Alert Level of Normal and the Aviation Color Code of Green to the category "unassigned." AVO stated that these volcanoes "will likely remain without real-time seismic monitoring until next summer, when necessary upgrades at these and other networks will occur. As at other volcanoes without real-time seismic networks, AVO will continue to use satellite data and reports from pilots and ground observers to detect signs of eruptive activity."

Following the announced station outage, the next update at Veniaminof was on 8 June 2013.

Pilots of aircraft PEN241 saw on 27 August 2013 intermittent ash discharges at 1720 UTC . "Occasional ash to [~3 km a.s.l.] moving NNE. Cloud height up to [~4 km a.s.l.] every 2-5 minutes." This reporting was transmitted to Air Traffic authorities and then to Bulletin editors via the Volcanic Activity Reporting Form (VAR; Appendix 2 of Federal Aviation Administration, 2012). Reports like these are valuable to engineers and scientists who benefit from the direct observations provided by pilots.

During 6-7 May 2009, seismic activity from Veniaminof increased, prompting AVO to raise the Volcanic Alert Level to Advisory and the Aviation Color Code to Yellow. Small magnitude earthquakes occurred at rates of 5-10 per hour during quieter periods and 1-3 per minute during periods of more intense activity. Visual observations indicated typical steaming from the summit caldera cone. Seismicity remained elevated during 8-12 May 2009. On 26 May 2009, AVO reported that seismicity from Veniaminof had decreased during the previous week. The Volcanic Alert Level was lowered to Normal and the Aviation Color Code was lowered to Green.

During 2010-12 the volcano was relatively quiet (table 1). There were no AVO weekly reports on Veniaminof during this interval.

On 13 June 2013, low-level emissions led the AVO to increase the aviation color code to orange. The Anchorage Volcanic Ash Advisory Center (VAAC) reported on 15 June 2013 that the eruptions had ended, but AVO still reported intermittent activity continuing through 8 July 2013. In addition, MODVOLC had detected 248 thermal alerts during 14 June-11 July 2013 (figure 13).

Figure (see Caption) Figure 13. This image of Veniaminof displays MODVOLC thermal alerts from 14 June 2013 to 11 July 2013. Thermal alerts from MODVOLC are derived from data collected by the MODIS thermal sensors aboard the Aqua and Terra satellites and processed by the Hawaii Institute of Geophysics and Planetology using the MODVOLC algorithm. Note that the hotspots (red) are clustered in the immediate region of the summit and are not wildfires.

July 2013 activity. Figure 14 shows a satellite image from 4 July 2013 portraying both ash desposits on the snow surface and the thermal signature of an ongoing lava flow. On 8 July 2013, AVO reported that nearly continuous, low-level volcanic tremor had occurred during the previous 24 hours. Cloudy satellite images detected thermal anomalies (figure 14). Web camera images from Perryville (32 m SSE) showed incandescence from the Veniaminof intracaldera cone.

Figure (see Caption) Figure 14. This satellite image from 4 July 2013 shows thermal emissions from an active lava flow as detected by shortwave infrared data, The image also shows ash deposits covering the snow fields that engulf the volcano. N is to the top. The ash appears as radial spokes due to deposition during changing wind directions. The lava flow was active at the time of this photo, extending southward from the vent. Image courtesy of Alaska Volcano Observatory.

AVO reported that the ongoing low-level eruption of Veniaminof, characterized by lava effusion and emission of minor amounts of ash and steam, continued during 26 June-8 July 2013, indicated by nearly continuous volcanic tremor and occasional small explosions detected by the seismic network. Figure 15 shows a photo taken on 26 June. Satellite images showed elevated surface temperatures at the cinder cone inside the caldera consistent with lava effusion. During 26-30 June web camera images from Perryville showed a small light-colored plume rising above the cone to just above the rim of the caldera, and night time images showed persistent incandescence from the cone. The Volcano Alert Level remained at Watch and the Aviation Color code remained at Orange.

Figure (see Caption) Figure 15. Steam rising from the active intracaldera cone of Veniaminof. The photo was taken from ~600 m elevation, looking SW toward the volcano on 26 June 2013. Photo courtesy of Will Lawrence.

2008-2011 seismicity. According to Dixon and others (2009) and additional AVO reports, the monitoring network for Veniaminof included nine stations, at least through 2011. The network experienced intermittent outages (eg. figure 16 of broken solar panel.) The number of recorded earthquakes between 2008-2011 is presented in table 1.

Figure (see Caption) Figure 16. Helena Buurman works to remove smashed solar panels at station VNFG- one of the main repeaters in the Veniaminof network (17 July 2010). Photo courtesy of Cyrus Read.

Table 2. Veniaminof VT and LF earthquakes detected during 2008-2011. Because of occasional equipment outages, values in the table may under-represent actual numbers. Values for 2012 were not yet available. Sources included Dixon and others (2008, 2009, 2010, 2011).

Year Earthquakes located Volcano-tectonic (VT) Low frequency (LF)
2008 17 14 3
2009 4 3 1
2010 22 18 4
2011 7 6 1

2009 annual seismicity. The Aniakchak, Cerberus, Gareloi, Great Sitkin, Pavlof, Veniaminof, and Wrangell subnetworks had insufficient numbers of located earthquakes to calculate a Mc. The Mc ranged from -0.1 to 1.5 for the individual subnetworks.

2010 annual seismicity. The seismograph networks on Aniakchak, Korovin, and Veniaminof were repaired in 2010. There were many station outages in the previous two years.

Seismicity at Veniaminof and Westdahl were the only areas in which an increase over the seismicity in 2009 was noted. The increase in seismicity at Veniaminof was a result of a small swarm of activity northwest of the active cone in late July.

2011 annual seismicity. There were fewer station outages and more than four were operating during the year. Veniaminof had insufficient numbers of located earthquakes in 2011 to calculate a magnitude completeness.

References. Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, C.K., 2011, Catalog of earthquake hypocenters at Alaskan Volcanoes: January 1 through December 31, 2010: U.S. Geological Survey Data Series 645, 82 p.

Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, C.K., 2012, Catalog of earthquake hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011: U.S. Geological Survey Data Series 730, 82 p.

Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, Cheryl, 2010, Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2009: U.S. Geological Survey Data Series 531, 84 p.

Dixon, J.P., and Stihler, S.D., 2009, Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2008: U.S. Geological Survey Data Series 467, 86 p.

Federal Aviation Administration, 2012, Aeronautical Information Manual, Official Guide to Basic Flight Information and ATC Procedures (issued 9 February 2012; with revisions as late as 22 Aug ust 2013) (URL: http://www.faa.gov/air_traffic/publications/atpubs/aim/index.htm).

Geologic Background. Veniaminof, on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.

Information Contacts: Alaska Volcano Observatory, a cooperative program of a)U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA URL: http://www.avo.alaska.edu/); b)Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320 USA and c)Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://www.dggs.alaska.gov/); Anchorage Volcanic Ash Advisory Center (VAAC), 6930 Sand lake Road Anchorage, AK 99502-1845 USA (URL: http://vaac.arh.noaa.gov/); and Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alert System, School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http:hotspot.higp.hawaiii.edu/).


Yasur (Vanuatu) — May 2013 Citation iconCite this Report

Yasur

Vanuatu

19.532°S, 169.447°E; summit elev. 361 m

All times are local (unless otherwise noted)


Explosive activity continued into at least early 2013

In BGVN 36:05, we reported that on 12 May 2011, the Vanuatu Geohazards Observatory (VGO) reported, based on information collected by the Vanuatu Meteorology and Geohazards Department, that a OMI (ozone monitoring instrument) satellite image showed strong degassing of SO2 from Yasur volcano during the previous week (see map of this island volcano in figure 42 of BGVN 36:05). On 1 June 2011, the Vanuatu Volcano Alert Level (VVAL) was raised from 2 to 3, following increasing explosive activity during May, then lowered to 2 on 13 June (table 3).

Table 3. The Vanuatu Volcanic Alert Level (VVAL) scale for the six volcanoes monitored by Vanuato Geohazard Observatory (Yasur, Lopevi, Ambrym, Aoba, Gaua, and Suretamatai). Courtesy of Vanuatu Geohazards Observatory.

VVAL Description
Lvl. ? Insufficient monitoring to make assessment.
Lvl. 0 Normal low-level activity.
Lvl. 1 Increased activity, danger near crater only.         
Lvl. 2 Moderate eruptions, danger close to the volcano vent, within parts of Volcanic Hazards Map Red Zone.
Lvl. 3 Large eruption, danger in specific areas within parts of Volcanic Hazards Map Red and Yellow Zones.    
Lvl. 4 Very large eruption, island-wide danger (including areas within Red Yellow and Green Zones).

During the week of 7-12 July 2012, VGO observed that explosive activity at Yasur became stronger and more frequent, and shifted from Strombolian to sub Plinian. Bombs ejected from the vents fell in the crater, around the summit area, and on the tourist walk and parking area (within the red zone, figure 43). The explosions were heard, felt, and observed from nearby villages and schools. Activity at all three volcanic vents was characterized by degassing, ash emissions, and ejection of bombs. On 13 July 2012, the Alert Level was raised to 3.

VGO reported an OMI satellite image on 1 April 2013 showed diffuse SO2 from Yasur. Explosive activity increased on 2 April 2013, with explosions becoming stronger and more frequent, and continued to slightly increase through 28 May. Bombs again fell around the summit area, the tourist walk, and the parking area. Moderate ash emissions and ashfall occurred on 2, 4, and 5 April, and 5 and 8 May 2013. Photos included in the report showed dense white plumes on 23 and 24 May. The Alert Level remained at 2 (on a scale of 0 4).

Volcano Ash Advisory Centre (VAAC) reports on Yasur. In many cases the VAAC lacked any satellite data and in cases where they did have data they frequently were unable to detect the plume or in other cases could not detect ash in the plume (table 4).

Table 4. Yasur volcano aviation reports (VAAs, Volcanic Ash Advisories) for the time interval 11 January 2009 to 10 June 2010. In many cases the information sources were the Vanuatu Geohazard Observatory (VGO). On 11 January the source was an AIREP, an aircraft report. Data provided courtesy of the Wellington Volcanic Ash Advisor Centre (VAAC).

Date (time UTC) Info Source (type of observation) Details Altitude (km) Drift or cited wind direction
11 Jan 2009 AIREP Plume sighted over volcano by aircraft (to ~4 km altitude, drifting SE). Ash not seen by VAAC analysts in satellite data. ~4km SE
29 May 2010 VGO Observatory reported plume, however no satellite image was made. ~2km Winds NE
30 May 2010 VGO Observatory reported plume, and a volcanic ash cloud was captured with a Modis image. ~2km Winds E
31 May 2010 VGO Observatory reported plume, and a volcanic ash cloud obscured the satellite image. ~2km Winds NE
01 Jun 2010 VGO Observatory reported plume, and a volcanic ash cloud obscured the satellite image. ~2km Winds N
02 Jun 2010 VGO Observatory reported plume, and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds N
03 Jun 2010 VGO Observatory reported plume, and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds E/NE
04 Jun 2010 VGO Observatory reported plume, and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds NE
05 Jun 2010 VGO Observatory reported a plume, and a volcanic ash could was unidentifiable on satellite image. A remark was made suggesting volcanic eruption may be easing. ~2km Winds NW
06 Jun 2010 VGO Observatory reported a plume,and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds NW
07 Jun 2010 VGO Observatory reported a plume, and satellite image was unavailable. ~2km Winds NW
08 Jun 2010 VGO Observatory reported a plume, and satellite image was unavailable. ~2km Winds NW
09 Jun 2010 VGO Observatory reported a plume, and satellite image was unavailable. ~2km Winds
10 Jun 2010 VGO Observatory reported a plume, and that no volcanic ash was visible on satellite image. ~2km Winds NE

Satellite Thermal Alerts. The MODIS/MODVOLC satellite thermal alert system has shown least 1 to 10 alerts each month over Yasur since the beginning of 2011. A lava lake has existed at Yasur for many years.

References. Allen, S.R., 2005, Complex spatter and pumice rich pyroclastic deposits from an andesitic caldera forming eruption:The Siwi pyroclastic sequence, Tanna, Vanuatu, Bulletin of Volcanology, v. 67, pp. 27 41.

Calmant, S., Pelletier, B., Lebellegard, P., Bevis, M., Taylor, F.W., and Phillips, D.A., 2003, New insights on the tectonics along the New Hebrides subduction zone based on GPS results, Journal of Geophysical Research, v. 108, no. B6, pp. 2319 2339.

Carnay, JN., and MacFarlane, A, 1979, Geology of Tanna, Aneityum, Futuna and Aniva, New Hebrides Geological Survey Report 1979, pp. 5 29.

Métrich, N., Allard, P., Aiuppa, A., Bani, P., Bertagnini, A., Shinohara, H., Parello, F., Di Muro, A., Garaebiti, E., Belhadj, O., and Massare, D., 2011, Magma and Volatile Supply to Post collapse Volcanism and Block Resurgence in Siwi Caldera (Tanna Island, Vanuatu Arc), Journal of Petrology, v. 52, no. 6, pp. 1077 1105; DOI: 10.1093/petrology/egr019.

Nairn, I.A., Scott, B.J., and Giggenbach, W.F., 1988, Yasur volcanic investigations, Vanuatu September 1988, New Zealand Geological Survey Report 1988, pp.1 74.

Pelletier, B., Calmant, S., and Pillet, R., 1998, Current tectonic of the Tonga New Hebrides region, Earth and Planetary Science Letters, v. 164, pp. 263 276.

Geologic Background. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous Strombolian and Vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.

Information Contacts: Vanuatu Geohazards Observatory, Department of Geology, Mines and Water Resources of Vanuatu (URL: http://www.geohazards.gov.vu); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov); MODIS/MODVOLC Thermal Alerts System, Hawai'i Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); and Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, URL: http://vaac.metservice.com/).

Atmospheric Effects

The enormous aerosol cloud from the March-April 1982 eruption of Mexico's El Chichón persisted for years in the stratosphere, and led to the Atmospheric Effects section becoming a regular feature of the Bulletin. Descriptions of the initial dispersal of major eruption clouds remain with the individual eruption reports, but observations of long-term stratospheric aerosol loading will be found in this section.

Atmospheric Effects (1980-1989)  Atmospheric Effects (1995-2001)

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements  Obituaries

Misc Reports

Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false. All of these types of additional reports are listed below by subject.

Additional Reports  False Reports