Kuchinoerabujima encompasses a group of young stratovolcanoes located in the northern Ryukyu Islands. All historical eruptions have originated from the Shindake cone, with the exception of a lava flow that originated from the S flank of the Furudake cone. The most recent previous eruptive period took place during October 2018-February 2019 and primarily consisted of weak explosions, ash plumes, and ashfall. The current eruption began on 11 January 2020 after nearly a year of dominantly gas-and-steam emissions. Volcanism for this reporting period from March 2019 to April 2020 included explosions, ash plumes, SO₂ emissions, and ashfall. The primary source of information for this report comes from monthly and annual reports from the Japan Meteorological Agency (JMA) and advisories from the Tokyo Volcanic Ash Advisory Center (VAAC). Activity has been limited to Kuchinoerabujima's Shindake Crater.

Volcanism at Kuchinoerabujima was relatively low during March through December 2019, according to JMA. During this time, SO₂ emissions ranged from 100 to 1,000 tons/day. Gas-and-steam emissions were frequently observed throughout the entire reporting period, rising to a maximum height of 1.1 km above the crater on 13 December 2019. Satellite imagery from Sentinel-2 showed gas-and-steam and occasional ash emissions rising from the Shindake crater throughout the reporting period (figure 7). Though JMA reported thermal anomalies occurring on 29 January and continuing through late April 2020, Sentinel-2 imagery shows the first thermal signature appearing on 26 April.

Figure 7. Sentinel-2 thermal satellite images showed gas-and-steam and ash emissions rising from Kuchinoerabujima. Some ash deposits can be seen on 6 February 2020 (top right). A thermal anomaly appeared on 26 April 2020 (bottom right). Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.

An eruption on 11 January 2020 at 1505 ejected material 300 m from the crater and produced ash plumes that rose 2 km above the crater rim, extending E, according to JMA. The eruption continued through 12 January until 0730. The resulting ash plumes rose 400 m above the crater, drifting SW while the SO₂ emissions measured 1,300 tons/day. Ashfall was reported on Yakushima Island (15 km E). Minor eruptive activity was reported during 17-20 January which produced gray-white plumes that rose 300-500 m above the crater. On 23 January, seismicity increased, and an eruption produced an ash plume that rose 1.2 km altitude, according to a Tokyo VAAC report, resulting in ashfall 2 km NE of the crater. A small explosion was detected on 24 January, followed by an increase in the number of earthquakes during 25-26 January (65-71 earthquakes per day were registered). Another small eruptive event detected on 27 January at 0148 was accompanied by a volcanic tremor and a change in tilt data. During the month of January, some inflation was detected at the base on the volcano and a total of 347 earthquakes were recorded. The SO₂ emissions ranged from 200-1,600 tons/day.

An eruption on 1 February 2020 produced an eruption column that rose less than 1 km altitude and extended SE and SW (figure 8), according to the Tokyo VAAC report. On 3 February, an eruption from the Shindake crater at 0521 produced an ash plume that rose 7 km above the crater and ejected material as far as 600 m away. As a result, a pyroclastic flow formed, traveling 900-1,500 m SW. The previous pyroclastic flow that was recorded occurred on 29 January 2019. Ashfall was confirmed in the N part of Yakushima Island with a large amount in Miyanoura (32 km ESE) and southern Tanegashima. The SO₂ emissions measured 1,700 tons/day during this event.

Figure 8. Webcam images from the Honmura west surveillance camera of an ash plume rising from Kuchinoerabujima on 1 February 2020. Courtesy of JMA (Weekly bulletin report 509, February 2020).

Intermittent small eruptive events occurred during 5-9 February; field observations showed a large amount of ashfall on the SE flank which included lapilli that measured up to 2 cm in diameter. Additionally, thermal images showed 5-km-long pyroclastic flow deposits on the SW flank. An eruption on 9 February produced an ash plume that rose 1.2 km altitude, drifting SE. On 13 February a small eruption was detected in the Shindake crater at 1211, producing gray-white plumes that rose 300 m above the crater, drifting NE. Small eruptive events also occurred during 20-21 February, resulting in gas-and-steam emissions that rose 200 m above the crater. During the month of February, some horizontal extension was observed since January 2020 using GNSS data. The total number of earthquakes during this month drastically increased to 1225 compared to January. The SO₂ emissions ranged from 300-1,700 tons/day.

By 2 March 2020, seismicity decreased, and activity declined. Gas-and-steam emissions continued infrequently for the duration of the reporting period. The SO₂ emissions during March ranged from 700-2,100 tons/day, the latter of which occurred on 15 March. Seismicity increased again on 27 March. During 5-8 April 2020, small eruptive events were detected, generating ash plumes that rose 900 m above the crater (figure 9). The SO₂ emissions on 6 April reached 3,200 tons/day, the maximum measurement for this reporting period. These small eruptive events continued from 13-20 and 23-25 April within the Shindake crater, producing gray-white plumes that rose 300-800 m above the crater.

Figure 9. Webcam images from the Honmura Nishi (top) and Honmura west (bottom) surveillance cameras of ash plumes rising from Kuchinoerabujima on 6 March and 5 April 2020. Courtesy of JMA (Weekly bulletin report 509, March and April 2020).

Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. The youngest cone, centrally-located Shindake, formed after the NW side of Furudake was breached by an explosion. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Information Contacts: Japan Meteorological Agency (JMA), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Soputan is a stratovolcano located in the northern arm of Sulawesi Island, Indonesia. Previous eruptive periods were characterized by ash explosions, lava flows, and Strombolian eruptions. The most recent eruption occurred during October-December 2018, which consisted mostly of ash plumes and some summit incandescence (BGVN 44:01). This report updates information for January 2019-April 2020 characterized by two ash plumes and gas-and-steam emissions. The primary source of information come from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and the Darwin Volcanic Ash Advisory Center (VAAC).

Activity during January 2019-April 2020 was relatively low; three faint thermal anomalies were observed at the summit at Soputan in satellite imagery for a total of three days on 2 and 4 January, and 1 October 2019 (figure 17). The MIROVA (Middle InfraRed Observation of Volcanic Activity) based on analysis of MODIS data detected 12 distal hotspots and six low-power hotspots within 5 km of the summit during August to early October 2019. A single distal thermal hotspot was detected in early March 2020. In March, activity primarily consisted of white to gray gas-and-steam plumes that rose 20-100 m above the crater, according to PVMBG. The Darwin VAAC issued a notice on 23 March 2020 that reported an ash plume rose to 4.3 km altitude; minor ash emissions had been visible in a webcam image the previous day (figure 18). A second notice was issued on 2 April, where an ash plume was observed rising 2.1 km altitude and drifting W.

Figure 17. Sentinel-2 thermal satellite imagery detected a total of three thermal hotspots (bright yellow-orange) at the summit of Soputan on 2 and 4 January and 1 October 2019. Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.

Figure 18. Minor ash emissions were seen rising from Soputan on 22 March 2020. Courtesy of MAGMA Indonesia.

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

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/); 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/); 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).

Heard Island is located on the Kerguelen Plateau in the southern Indian Ocean and contains Big Ben, a snow-covered stratovolcano with intermittent volcanism reported since 1910. Due to its remote location, visual observations are rare; therefore, thermal anomalies and hotspots detected by satellite-based instruments are the primary source of information. This report updates activity from October 2019 to April 2020.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed three prominent periods of strong thermal anomaly activity during this reporting period: late October 2019, December 2019, and the end of April 2020 (figure 41). These thermal anomalies were relatively strong and occurred within 5 km of the summit. Similarly, the MODVOLC algorithm reported a total of six thermal hotspots during 28 October, 1 November 2019, and 26 April 2020.

Figure 41. Thermal anomalies at Heard from 29 April 2019 through April 2020 as recorded by the MIROVA system (Log Radiative Power) were strong and frequent in late October, during December 2019, and at the end of April 2020. Courtesy of MIROVA.

Six thermal satellite images ranging from late October 2019 to late March showed evidence of active lava at the summit (figure 42). These images show hot material, possibly a lava flow, extending SW from the summit; a hotspot also remained at the summit. Cloud cover was pervasive during the majority of this reporting period, especially in April 2020, though gas-and-steam emissions were visible on 25 April through the clouds.

Figure 42. Thermal satellite images of Heard Island’s Big Ben showing strong thermal signatures representing a lava flow in the SW direction from 28 October to 17 December 2019. These thermal anomalies are located NE from Mawson Peak. A faint thermal anomaly is also captured on 26 March 2020. Satellite images with atmospheric penetration (bands 12, 11, and 8A), courtesy of Sentinel Hub Playground.

Geologic Background. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The historically active Mawson Peak forms the island's high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.

Information Contacts: 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).

The Kikai caldera is located at the N end of Japan’s Ryukyu Islands and has been recently characterized by intermittent ash emissions and limited ashfall in nearby communities. On Satsuma Iwo Jima island, the larger subaerial fragment of the Kikai caldera, there was a single explosion with gas-and-steam and ash emissions on 2 November 2019, accompanied by nighttime incandescence (BGVN 45:02). This report covers volcanism from January 2020 through April 2020 with a single-day eruption occurring on 29 April based on reports from the Japan Meteorological Agency (JMA).

Since the last one-day eruption on 2 November 2019, volcanism at Kikai has been relatively low and primarily consisted of 107-170 earthquakes per month and intermittent white gas-and-steam emissions rising up to 1.3 km above the crater summit. Intermittent weak hotspots were observed at night in the summit in Sentinel-2 thermal satellite imagery and webcams, according to JMA (figures 14 and 15).

Figure 14. Weak thermal hotspots (bright yellow-orange) were observed on 7 January (top) and 6 April 2020 (bottom) at Satsuma Iwo Jima (Kikai). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

Figure 15. Incandescence at night on 10 January 2020 was observed at Satsuma Iwo Jima (Kikai) in the Iodake crater with the Iwanogami webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, January 2nd year of Reiwa [2020]).

Weak incandescence continued in April 2020. JMA reported SO₂ measurements during April were 400-2000 tons/day. A brief eruption in the Iodake crater on 29 April 2020 at 0609 generated a gray-white ash plume that rose 1 km above the crater (figure 16). No ashfall or ejecta was observed after the eruption on 29 April.

Figure 16. The Iwanogami webcam captured a brief gray-white ash and steam plume rising above the Iodake crater rim on Satsuma Iwo Jima (Kikai) on 29 April 2020 at 0609 local time. The plume rose 1 km above the crater summit. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, April 2nd year of Reiwa [2020]).

Geologic Background. Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Fuego is a stratovolcano in Guatemala that has been erupting since 2002 with historical eruptions that date back to 1531. Volcanism is characterized by major ashfalls, pyroclastic flows, lava flows, and lahars. The previous report (BGVN 44:10) detailed activity that included multiple ash explosions, ash plumes, ashfall, active lava flows, and block avalanches. This report covers this continuing activity from October 2019 through March 2020 and consists of ash plumes, ashfall, incandescent ejecta, block avalanches, and lava flows. The primary source of information comes from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Washington Volcanic Ash Advisory Center (VAAC), and various satellite data.

Summary of activity October 2019-March 2020. Daily activity persisted throughout October 2019-March 2020 (table 20) with multiple ash explosions recorded every hour, ash plumes that rose to a maximum of 4.8 km altitude each month drifting in multiple directions, incandescent ejecta reaching a 500 m above the crater resulting in block avalanches traveling down multiple drainages, and ashfall affecting communities in multiple directions. The highest rate of explosions occurred on 7 November with up to 25 per hour. Dominantly white fumaroles occurred frequently throughout this reporting period, rising to a maximum altitude of 4.5 km and drifting in multiple directions. Intermittent lava flows that reached a maximum length of 1.2 km were observed each month in the Seca (Santa Teresa) and Ceniza drainages (figure 128), but rarely in the Trinidad drainage. Thermal activity increased slightly in frequency and strength in late October and remained relatively consistent through mid-March as seen in the MIROVA analysis of MODIS satellite data (figure 129).

Table 20. Activity summary by month for Fuego with information compiled from INSIVUMEH daily reports.

Figure 128. Sentinel-2 thermal satellite images of Fuego between 21 November 2019 and 20 March 2020 showing lava flows (bright yellow-orange) traveling generally S and W from the crater summit. An ash plume can also be seen on 21 November 2019, accompanying the lava flow. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

Figure 129. Thermal activity at Fuego increased in frequency and strength (log radiative power) in late October 2019 and remained relatively consistent through February 2020. In early March, there is a small decrease in thermal power, followed by a short pulse of activity and another decline. Courtesy of MIROVA.

Activity during October-December 2019. Activity in October 2019 consisted of 6-20 ash explosions per hour; ash plumes rose to 4.8 km altitude, drifting up to 25 km in multiple directions, resulting in ashfall in Panimaché I and II (8 km SW), Morelia (9 km SW), San Pedro Yepocapa (8 km NW), Sangre de Cristo (8 km WSW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, La Rochela and San Andrés Osuna. The Washington VAAC issued multiple aviation advisories for a total of nine days in October. Continuous white gas-and-steam plumes reached 4.1-4.4 km altitude drifting generally W. Weak SO₂ emissions were infrequently observed in satellite imagery during October and January 2020 (figure 130) Incandescent ejecta was frequently observed rising 200-400 m above the summit, which generated block avalanches that traveled down the Seca (W), Taniluyá (SW), Ceniza (SSW), Trinidad (S), El Jute, Honda, and Las Lajas (SE) drainages. During 3-7 October lahars descended the Ceniza, El Mineral, and Seca drainages, carrying tree branches, tree trunks, and blocks 1-3 m in diameter. During 6-8 and 13 October, active lava flows traveled up to 200 m down the Seca drainage.

Figure 130. Weak SO2 emissions were observed rising from Fuego using the TROPOMI instrument on the Sentinel-5P satellite. Top left: 17 October 2019. Top right: 17 November 2019. Bottom left: 20 January 2020. Bottom right: 22 January 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

During November 2019, the rate of explosions increased to 5-25 per hour, the latter of which occurred on 7 November. The explosions resulted in ash plumes that rose 4-4.8 km altitude, drifting 10-20 km in the W direction. Ashfall was observed in Panimaché I and II, Morelia, Santa Sofía, Porvenir, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa. Multiple Washington VAAC notices were issued for 11 days in November. Continuous white gas-and-steam plumes rose up to 4.5 km altitude drifting generally W. Incandescent ejecta rose 100-500 m above the crater, generating block avalanches in Seca, Taniluyá, Trinidad, Las Lajas, Honda, and Ceniza drainages. Lava flows were observed for a majority of the month into early December measuring 100-900 m long in the Seca and Ceniza drainages.

The number of explosions in December 2019 decreased compared to November, recording 8-19 per hour with incandescent ejecta rising 100-400 m above the crater. The explosions generated block avalanches that traveled in the Seca, Taniluya, Ceniza, Trinidad, and Las Lajas drainages throughout the month. Ash plumes continued to rise above the summit crater to 4.8 km drifting up to 25 km in multiple directions. The Washington VAAC issued multiple daily notices almost daily in December. A continuous lava flow observed during 6-15, 21-22, 24, and 26 November through 9 December measured 100-800 m long in the Seca and Ceniza drainages.

Activity during January-March 2020. Incandescent Strombolian explosions continued daily during January 2020, ejecting material up to 100-500 m above the crater. Ash plumes continued to rise to a maximum altitude of 4.8 km, resulting in ashfall in all directions affecting Morelia, Santa Sofía, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, El Porvenir, Finca Palo Verde, Rodeo, La Rochela, Alotenango, El Zapote, Trinidad, La Reina, and Ceilán. The Washington VAAC issued multiple notices for a total of 12 days during January. Block avalanches resulting from the Strombolian explosions traveled down the Seca, Ceniza, Taniluyá, Trinidad, Honda, and Las Lajas drainages. An active lava flow in the Ceniza drainage measured 150-600 m long during 6-10 January.

During February 2020, INSIVUMEH reported a range of 4-16 explosions per hour, accompanied by incandescent material that rose 100-500 m above the crater (figure 131). Block avalanches traveled in the Santa Teresa, Seca, Ceniza, Taniluya, Trinidad, Las Lajas, Honda, La Rochela, El Zapote, and San Andrés Osuna drainages. Ash emissions from the explosions continued to rise 4.8 km altitude, drifting in multiple directions as far as 25 km and resulting in ashfall in the communities of Panimache I and II, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, Rodeo, La Reina, Alotenango, Yucales, Siquinalá, Santa Lucia, El Porvenir, Finca Los Tarros, La Soledad, Buena Vista, La Cruz, Pajales, San Miguel Dueñas, Ciudad Vieja, San Miguel Escobar, San Pedro las Huertas, Antigua, La Rochela, and San Andrés Osuna. Washington VAAC notices were issued almost daily during the month. Lava flows were active in the Ceniza drainage during 13-20, 23-24, and 26-27 February measuring as long as 1.2 km.

Figure 131. Incandescent ejecta rose several hundred meters above the crater of Fuego on 6 February 2020, resulting in block avalanches down multiple drainages. Courtesy of Crelosa.

Daily explosions and incandescent ejecta continued through March 2020, with 8-17 explosions per hour that rose up to 500 m above the crater. Block avalanches from the explosions were observed in the Seca, Ceniza, Trinidad, Taniluyá, Las Lajas, Honda, Santa Teresa, La Rochela, El Zapote, San Andrés Osuna, Morelia, Panimache, and Santa Sofia drainages. Accompanying ash plumes rose 4.8 km altitude, drifting in multiple directions mostly to the W as far as 23 km and resulting in ashfall in San Andrés Osuna, La Rochela, El Rodeo, Chuchu, Panimache I and II, Santa Sofia, Morelia, Finca Palo Verde, El Porvenir, Sangre de Cristo, La Cruz, San Pedro Yepocapa, La Conchita, La Soledad, Alotenango, Aldea la Cruz, Acatenango, Ceilan, Taniluyá, Ceniza, Las Lajas, Trinidad, Seca, and Honda. Multiple Washington VAAC notices were issued for a total of 15 days during March. Active lava flows were observed from 16-21 March in the Trinidad and Ceniza drainages measuring 400-1,200 m long and were accompanied by weak to moderate explosions. By 23 March, active lava flows were no longer observed.

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: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); 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); 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); Crelosa, 3ra. avenida. 8-66, Zona 14. Colonia El Campo, Guatemala Ciudad de Guatemala (URL: http://crelosa.com/, post at https://www.youtube.com/watch?v=1P4kWqxU2m0&feature=youtu.be).

The current moderate explosive eruption of Ebeko has been ongoing since October 2016, with frequent ash explosions that have reached altitudes of 1.3-6 km (BGVN 42:08, 43:03, 43:06, 43:12, 44:12). Ashfall is common in Severo-Kurilsk, a town of about 2,500 residents 7 km ESE, where the Kamchatka Volcanic Eruptions Response Team (KVERT) monitor the volcano. During the reporting period, December 2019-May 2020, the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

During December 2019-May 2020, frequent explosions generated ash plumes that reached altitudes of 1.5-4.6 km (table 9); reports of ashfall in Severo-Kurilsk were common. Ash explosions in late April caused ashfall in Severo-Kurilsk during 25-30 April (figure 24), and the plume drifted 180 km SE on the 29th. There was also a higher level of activity during the second half of May (figure 25), when plumes drifted up to 80 km downwind.

Table 9. Summary of activity at Ebeko, December 2019-May 2020. S-K is Severo-Kurilsk (7 km ESE of the volcano). TA is thermal anomaly in satellite images. In the plume distance column, only plumes that drifted more than 10 km are indicated. Dates based on UTC times. Data courtesy of KVERT.

Figure 24. Photo of ash explosion at Ebeko at 2110 UTC on 28 April 2020, as viewed from Severo-Kurilsk. Courtesy of KVERT (L. Kotenko).

Figure 25. Satellite image of Ebeko from Sentinel-2 on 27 May 2020, showing a plume drifting SE. Image using natural color rendering (bands 4, 3, 2) courtesy of Sentinel Hub Playground.

Geologic Background. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion 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/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. Recent volcanism is characterized by multiple fissure eruptions, lava fountains, and lava flows (BGVN 44:11). The activity during this reporting period of November 2019-April 2020 is consistent with the previous eruption, including lava fountaining and lava flows. Information for this report comes from the Observatoire Volcanologique du Piton de la Fournaise (OVPF) and various satellite data.

Activity during November 2019-January 2020 was relatively low; no eruptive events were detected, according to OVPF. Edifice deformation resumed during the last week in December and continued through January. Seismicity significantly increased in early January, registering 258 shallow earthquakes from 1-16 January. During 17-31 January, the seismicity declined, averaging one earthquake per day.

Two eruptive events took place during February-April 2020. OVPF reported that the first occurred from 10 to 16 February on the E and SE flanks of the Dolomieu Crater. The second took place during 2-6 April. Both eruptive events began with a sharp increase in seismicity accompanied by edifice inflation, followed by a fissure eruption that resulted in lava fountains and lava flows (figure 193). MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed the two eruptive events occurring during February-April 2020 (figure 194). Similarly, the MODVOLC algorithm reported 72 thermal signatures proximal to the summit crater from 12 February to 6 April. Both of these eruptive events were accompanied by SO2 emissions that were detected by the Sentinel-5P/TROPOMI instrument (figures 195 and 196).

Figure 193. Location maps of the lava flows on the E flank at Piton de la Fournaise on 10-16 February 2020 (left) and 2-6 April 2020 (right) as derived from SAR satellite data. Courtesy of OVPF-IPGP, OPGC, LMV (Monthly bulletins of the Piton de la Fournaise Volcanological Observatory, February and April 2020).

Figure 194. Two significant eruptive events at Piton de la Fournaise took place during February-April 2020 as recorded by the MIROVA system (Log Radiative Power). Courtesy of MIROVA.

Figure 195. Images of the SO2 emissions during the February 2020 eruptive event at Piton de la Fournaise detected by the Sentinel-5P/TROPOMI satellite. Top left: 10 February 2020. Top right: 11 February 2020. Bottom left: 13 February 2020. Bottom right: 14 February 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Figure 196. Images of the SO2 emissions during the April 2020 eruptive event at Piton de la Fournaise detected by the Sentinel-5P/TROPOMI satellite. Left: 4 April 2020. Middle: 5 April 2020. Right: 6 April 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

On 10 February 2020 a seismic swarm was detected at 1027, followed by rapid deformation. At 1050, volcanic tremors were recorded, signaling the start of the eruption. Several fissures opened on the E flank of the Dolomieu Crater between the crater rim and at 2,000 m elevation, as observed by an overflight during 1300 and 1330. These fissures were at least 1 km long and produced lava fountains that rose up to 10 m high. Lava flows were also observed traveling E and S to 1,700 m elevation by 1315 (figures 197 and 198). The farthest flow traveled E to an elevation of 1,400 m. Satellite data from HOTVOLC platform (OPGC - University of Auvergne) was used to estimate the peak lava flow rate on 11 February at 10 m3/s. By 13 February only one lava flow that was traveling E below the Marco Crater remained active. OVPF also reported the formation of a cone, measuring 30 m tall, surrounded by three additional vents that produced lava fountains up to 15 m high. On 15 February the volcanic tremors began to decrease at 1400; by 16 February at 1412 the tremors stopped, indicating the end of the eruptive event.

Figure 197. Photo of a lava flow and degassing at Piton de la Fournaise on 10 February 2020. Courtesy of OVPF-IPGP.

Figure 198. Photos of the lava flows at Piton de la Fournaise taken during the February 2020 eruption by Richard Bouchet courtesy of AFP News Service.

Volcanism during the month of March 2020 consisted of low seismicity, including 21 shallow volcanic tremors and near the end of the month, edifice inflation was detected. A second eruptive event began on 2 April 2020, starting with an increase in seismicity during 0815-0851. Much of this seismicity was located on the SE part of the Dolomieu Crater. A fissure opened on the E flank, consistent with the fissures that were active during the February 2020 event. Seismicity continued to increase in intensity through 6 April located dominantly in the SE part of the Dolomieu Crater. An overflight on 5 April at 1030 showed lava fountains rising more than 50 m high accompanied by gas-and-steam plumes rising to 3-3.5 km altitude (figures 199 and 200). A lava flow advanced to an elevation of 360 m, roughly 2 km from the RN2 national road (figure 199). A significant amount of Pele’s hair and clusters of fine volcanic products were produced during the more intense phase of the eruption (5-6 April) and deposited at distances more than 10 km from the eruptive site (figure 201). It was also during this period that the SO2 emissions peaked (figure 196). The eruption stopped at 1330 after a sharp decrease in volcanic tremors.

Figure 199. Photos of a lava flow (left) and lava fountains (right) at Piton de la Fournaise during the April 2020 eruption. Left: photo taken on 2 April 2020 at 1500. Right: photo taken on 5 April 2020 at 1030. Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, April 2020).

Figure 200. Photo of the lava fountains erupting from Piton de la Fournaise on 4 April 2020. Photo taken by Richard Bouchet courtesy of Geo Magazine via Jeannie Curtis.

Figure 201. Photos of Pele’s hair deposited due to the April 2020 eruption at Piton de la Fournaise. Samples collected near the Gîte du volcan on 7 April 2020 (left) and a cluster of Pele’s hair found near the Foc-Foc car park on 9 April 2020 (right). Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, April 2020).

Geologic Background. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.

Information Contacts: Observatoire Volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, 14 route nationale 3, 27 ème km, 97418 La Plaine des Cafres, La Réunion, France (URL: http://www.ipgp.fr/fr); 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/); 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); GEO Magazine (AFP story at URL: https://www.geo.fr/environnement/la-reunion-fin-deruption-au-piton-de-la-fournaise-200397); AFP (URL: https://twitter.com/AFP/status/1227140765106622464, Twitter: @AFP, https://twitter.com/AFP); Jeannie Curtis (Twitter: @VolcanoJeannie, https://twitter.com/VolcanoJeannie).

Although tephrochronology has dated activity at Sabancaya back several thousand years, renewed activity that began in 1986 was the first recorded in over 200 years. Intermittent activity since then has produced significant ashfall deposits, seismic unrest, and fumarolic emissions. A new period of explosive activity that began in November 2016 has been characterized by pulses of ash emissions with some plumes exceeding 10 km altitude, thermal anomalies, and significant SO₂ plumes. Ash emissions and high levels of SO₂ continued each week during December 2019-May 2020. The Observatorio Vulcanologico INGEMMET (OVI) reports weekly on numbers of daily explosions, ash plume heights and directions of drift, seismicity, and other activity. The Buenos Aires Volcanic Ash Advisory Center (VAAC) issued three or four daily reports of ongoing ash emissions at Sabancaya throughout the period.

The dome inside the summit crater continued to grow throughout this period, along with nearly constant ash, gas, and steam emissions; the average number of daily explosions ranged from 4 to 29. Ash and gas plume heights rose 1,800-3,800 m above the summit crater, and multiple communities around the volcano reported ashfall every month (table 6). Sulfur dioxide emissions were notably high and recorded daily with the TROPOMI satellite instrument (figure 75). Thermal activity declined during December 2019 from levels earlier in the year but remained steady and increased in both frequency and intensity during April and May 2020 (figure 76). Infrared satellite images indicated that the primary heat source throughout the period was from the dome inside the summit crater (figure 77).

Table 6. Persistent activity at Sabancaya during December 2019-May 2020 included multiple daily explosions with ash plumes that rose several kilometers above the summit and drifted in many directions; this resulted in ashfall in communities within 30 km of the volcano. Satellite instruments recorded SO₂ emissions daily. Data courtesy of OVI-INGEMMET.

Figure 75. Sulfur dioxide anomalies were captured daily from Sabancaya during December 2019-May 2020 by the TROPOMI instrument on the Sentinel-5P satellite. Some of the largest SO2 plumes are shown here with dates listed in the information at the top of each image. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Figure 76. Thermal activity at Sabancaya declined during December 2019 from levels earlier in the year but remained steady and increased slightly in frequency and intensity during April and May 2020, according to the MIROVA graph of Log Radiative Power from 23 June 2019 through May 2020. Courtesy of MIROVA.

Figure 77. Sentinel-2 satellite imagery of Sabancaya confirmed the frequent ash emissions and ongoing thermal activity from the dome inside the summit crater during December 2019-May 2020. Top row (left to right): On 6 December 2019 a large plume of steam and ash drifted N from the summit. On 16 December 2019 a thermal anomaly encircled the dome inside the summit caldera while gas and possible ash drifted NW. On 14 April 2020 a very similar pattern persisted inside the crater. Bottom row (left to right): On 19 April an ash plume was clearly visible above dense cloud cover. On 24 May the infrared glow around the dome remained strong; a diffuse plume drifted W. A large plume of ash and steam drifted SE from the summit on 29 May. Infrared images use Atmospheric penetration rendering (bands 12, 11, 8a), other images use Natural Color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

The average number of daily explosions during December 2019 decreased from a high of 16 the first week of the month to a low of five during the last week. Six pyroclastic flows occurred on 10 December (figure 78). Tremors were associated with gas-and-ash emissions for most of the month. Ashfall was reported in Pinchollo, Madrigal, Lari, Maca, Achoma, Coporaque, Yanque, and Chivay during the first week of the month, and in Huambo and Cabanaconde during the second week (figure 79). Inflation of the volcano was measured throughout the month. SO₂ flux was measured by OVI as ranging from 2,500 to 4,300 tons per day.

Figure 78. Multiple daily explosions at Sabancaya produced ash plumes that rose several kilometers above the summit. Left image is from 5 December and right image is from 11 December 2019. Note pyroclastic flows to the right of the crater on 11 December. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-49-2019/INGEMMET Semana del 2 al 8 de diciembre de 2019 and RSSAB-50-2019/INGEMMET Semana del 9 al 15 de diciembre de 2019).

Figure 79. Communities to the N and W of Sabancaya recorded ashfall from the volcano the first week of December and also every month during December 2019-May 2020. The red zone is the area where access is prohibited (about a 12-km radius from the crater). Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-22-2020/INGEMMET Semana del 25 al 31 de mayo del 2020).

During January and February 2020 the number of daily explosions averaged 4-20. Ash plumes rose as high as 3.4 km above the summit (figure 80) and drifted up to 30 km in multiple directions. Ashfall was reported in Chivay, Yanque, and Achoma on 8 January, and in Huambo on 25 February. Sulfur dioxide flux ranged from a low of 1,200 t/d on 29 February to a high of 8,200 t/d on 28 January. Inflation of the edifice was measured during January; deformation changed to deflation in early February but then returned to inflation by the end of the month.

Figure 80. Ash plumes rose from Sabancaya every day during January and February 2020. Left: 11 January. Right: 28 February. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-02-2020/INGEMMET Semana del 06 al 12 de enero del 2020 and RSSAB-09-2020/INGEMMET Semana del 24 de febrero al 01 de marzo del 2020).

Explosions continued during March and April 2020, averaging 8-29 per day. Explosions appeared to come from multiple vents on 11 March (figure 81). Ash plumes rose 3 km above the summit during the first week of March and again the first week of April; they were lower during the other weeks. Ashfall was reported in Madrigal, Lari, and Pinchollo on 27 March and 5 April. On 17 April ashfall was reported in Maca, Ichupampa, Yanque, Chivay, Coporaque, and Achoma. Sulfur dioxide flux ranged from 1,900 t/d on 5 March to 10,700 t/d on 30 March. Inflation at depth continued throughout March and April with 10 +/- 4 mm recorded between 21 and 26 April. Similar activity continued during May 2020; explosions averaged 6-16 per day (figure 82). Ashfall was reported on 6 May in Chivay, Achoma, Maca, Lari, Madrigal, and Pinchollo; heavy ashfall was reported in Achoma on 12 May. Additional ashfall was reported in Achoma, Maca, Madrigal, and Lari on 23 May.

Figure 81. Explosions at Sabancaya on 11 March 2020 appeared to originate simultaneously from two different vents (left). The plume on 12 April was measured at about 2,500 m above the summit. Courtesy of OVI-INGEMMET (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-11-2020/INGEMMET Semana del 9 al 15 de marzo del 2020 and RSSAB-15-2020/INGEMMET Semana del 6 al 12 de abril del 2020).

Figure 82. Explosions dense with ash continued during May 2020 at Sabancaya. On 11 and 29 May 2020 ash plumes rose from the summit and drifted as far as 30 km before dissipating. Courtesy of OVI-INGEMMET (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya , RSSAB-20-2020/INGEMMET Semana del 11 al 17 de mayo del 2020 and RSSAB-22-2020/INGEMMET Semana del 25 al 31 de mayo del 2020).

Geologic Background. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Information Contacts: Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, Peru (URL: http://ovi.ingemmet.gob.pe); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); 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/); 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).

The eruption at Sheveluch has continued for more than 20 years, with strong explosions that have produced ash plumes, lava dome growth, hot avalanches, numerous thermal anomalies, and strong fumarolic activity (BGVN 44:05). During this time, there have been periods of greater or lesser activity. The most recent period of increased activity began in December 2018 and continued through October 2019 (BGVN 44:11). This report covers activity between November 2019 to April 2020, a period during which activity waned. The volcano is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT) and Tokyo Volcanic Ash Advisory Center (VAAC).

During the reporting period, KVERT noted that lava dome growth continued, accompanied by incandescence of the dome blocks and hot avalanches. Strong fumarolic activity was also present (figure 53). However, the overall eruption intensity waned. Ash plumes sometimes rose to 10 km altitude and drifted downwind over 600 km (table 14). The Aviation Color Code (ACC) remained at Orange (the second highest level on a four-color scale), except for 3 November when it was raised briefly to Red (the highest level).

Figure 53. Fumarolic activity of Sheveluch’s lava dome on 24 January 2020. Photo by Y. Demyanchuk; courtesy of KVERT.

Table 14. Explosions and ash plumes at Sheveluch during November 2019-April 2020. Dates and times are UTC, not local. Data courtesy of KVERT and the Tokyo VAAC.

KVERT reported thermal anomalies over the volcano every day, except for 25-26 January, when clouds obscured observations. During the reporting period, thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm recorded hotspots on 10 days in November, 13 days in December, nine days in January, eight days in both February and March, and five days in April. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, detected numerous hotspots every month, almost all of which were of moderate radiative power (figure 54).

Figure 54. Thermal anomalies at Sheveluch continued at elevated levels during November 2019-April 2020, as seen on this MIROVA Log Radiative Power graph for July 2019-April 2020. Courtesy of MIROVA.

High sulfur dioxide levels were occasionally recorded just above or in the close vicinity of Sheveluch by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite, but very little drift was observed.

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

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/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); 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/); 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); 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/).

The ongoing eruption at Dukono is characterized by frequent explosions that send ash plumes to about 1.5-3 km altitude (0.3-1.8 km above the summit), although a few have risen higher. This type of typical activity (figure 13) continued through at least March 2020. The ash plume data below (table 21) were primarily provided by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and the Darwin Volcanic Ash Advisory Centre (VAAC). During the reporting period of October 2019-March 2020, the Alert Level remained at 2 (on a scale of 1-4) and the public was warned to remain outside of the 2-km exclusion zone.

Table 21. Monthly summary of reported ash plumes from Dukono for October 2019-March 2020. The direction of drift for the ash plume through each month was highly variable; notable plume drift each month was only indicated in the table if at least two weekly reports were consistent. Data courtesy of the Darwin VAAC and PVMBG.

Figure 13.Satellite image of Dukono from Sentinel-2 on 12 November 2019, showing an ash plume drifting E. Image uses natural color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

During the reporting period, high levels of sulfur dioxide were only recorded above or near the volcano during 30-31 October and 4 November 2019. High levels were recorded by the Ozone Mapping and Profiler Suite (OMPS) instrument aboard the Suomi National Polar-orbiting Partnership (NPP) satellite on 30 October 2019, in a plume drifting E. The next day high levels were also recorded by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite on 31 October (figure 14) and 4 November 2019, in plumes drifting SE and NE, respectively.

Figure 14. Sulfur dioxide emission on 31 October 2019 drifting E, probably from Dukono, as recorded by the TROPOMI instrument aboard the Sentinel-5P satellite. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Geologic Background. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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/); 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/); 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).

Mount Etna is a stratovolcano located on the island of Sicily, Italy, with historical eruptions that date back 3,500 years. The most recent eruptive period began in September 2013 and has continued through March 2020. Activity is characterized by Strombolian explosions, lava flows, and ash plumes that commonly occur from the summit area, including the Northeast Crater (NEC), the Voragine-Bocca Nuova (or Central) complex (VOR-BN), the Southeast Crater (SEC, formed in 1978), and the New Southeast Crater (NSEC, formed in 2011). The newest crater, referred to as the "cono della sella" (saddle cone), emerged during early 2017 in the area between SEC and NSEC. This reporting period covers information from October 2019 through March 2020 and includes frequent explosions and ash plumes. The primary source of information comes from the Osservatorio Etneo (OE), part of the Catania Branch of Italy's Istituo Nazionale di Geofisica e Vulcanologica (INGV).

Summary of activity during October 2019-March 2020. Strombolian activity and gas-and-steam and ash emissions were frequently observed at Etna throughout the entire reporting period, according to INGV and Toulouse VAAC notices. Activity was largely located within the main cone (Voragine-Bocca Nuova complex), the Northeast Crater (NEC), and the New Southeast Crater (NSEC). On 1, 17, and 19 October, ash plumes rose to a maximum altitude of 5 km. Due to constant Strombolian explosions, ground observations showed that a scoria cone located on the floor of the VOR Crater had begun to grow in late November and again in late January 2020. A lava flow was first detected on 6 December at the base of the scoria cone in the VOR Crater, which traveled toward the adjacent BN Crater. Additional lava flows were observed intermittently throughout the reporting period in the same crater. On 13 March, another small scoria cone had formed in the main VOR-BN complex due to Strombolian explosions.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows multiple episodes of thermal activity varying in power from 22 June 2019 to March 2020 (figure 286). The power and frequency of these thermal anomalies significantly decreased between August to mid-September. The pulse of activity in mid-September reflected a lava flow from the VOR Crater (BGVN 44:10). By late October through November, thermal anomalies were relatively weaker and less frequent. The next pulse in thermal activity reflected in the MIROVA graph occurred in early December, followed by another shortly after in early January, both of which were due to new lava flows from the VOR Crater. After 9 January the thermal anomalies remained frequent and strong; active lava flows continued through March accompanied by Strombolian explosions, gas-and-steam, SO2, and ash emissions. The most recent distinct pulse in thermal activity was seen in mid-March; on 13 March, another lava flow formed, accompanied by an increase in seismicity. This lava flow, like the previous ones, also originated in the VOR Crater and traveled W toward the BN Crater.

Figure 286. Multiple episodes of varying activity at Etna from 22 June 2019 through March 2020 were reflected in the MIROVA thermal energy data (Log Radiative Power). Courtesy of MIROVA.

Activity during October-December 2019. During October 2019, VONA (Volcano Observatory Notice for Aviation) notices issued by INGV reported ash plumes rose to a maximum altitude of 5 km on 1, 17, and 19 October. Strombolian explosions occurred frequently. Explosions were detected primarily in the VOR-BN Craters, ejecting coarse pyroclastic material that fell back into the crater area and occasionally rising above the crater rim. Ash emissions rose from the VOR-BN and NEC while intense gas-and-steam emissions were observed in the NSEC (figure 287). Between 10-12 and 14-20 October fine ashfall was observed in Pedara, Mascalucia, Nicolosi, San Giovanni La Punta, and Catania. In addition to these ash emissions, the explosive Strombolian activity contributed to significant SO2 plumes that drifted in different directions (figure 288).

Figure 287. Webcam images of ash emissions from the NE Crater at Etna from the a) CUAD (Catania) webcam on 10 October 2019; b) Milo webcam on 11 October 2019; c) Milo webcam on 12 October 2019; d) M.te Cagliato webcam on 13 October 2019. Courtesy of INGV (Report 42/2019, ETNA, Bollettino Settimanale, 07/10/2019 - 13/10/2019, data emissione 15/10/2019).

Figure 288. Strombolian activity at Etna contributed to significant SO2 plumes that drifted in multiple directions during the intermittent explosions in October 2019. Top left: 1 October 2019. Top right: 2 October 2019. Middle left: 15 October 2019. Middle right: 18 October 2019. Bottom left: 13 November 2019. Bottom right: 1 December 2019. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.

The INGV weekly bulletin covering activity between 25 October and 1 November 2019 reported that Strombolian explosions occurred at intervals of 5-10 minutes from within the VOR-BN and NEC, ejecting incandescent material above the crater rim, accompanied by modest ash emissions. In addition, gas-and-steam emissions were observed from all the summit craters. Field observations showed the cone in the crater floor of VOR that began to grow in mid-September 2019 had continued to grow throughout the month. During the week of 4-10 November, Strombolian activity within the Bocca Nuova Crater was accompanied by gas-and-steam emissions. The explosions in the VOR Crater occasionally ejected incandescent ejecta above the crater rim (figures 289 and 290). For the remainder of the month Strombolian explosions continued in the VOR-BN and NEC, producing sporadic ash emissions. Isolated and discontinuous explosions in the New Southeast Crater (NSEC) also produced fine ash, though gas-and-steam emissions still dominated the activity at this crater. Additionally, the explosions from these summit craters were frequently accompanied by strong SO2 emissions that drifted in different directions as discrete plumes.

Figure 289. Photo of Strombolian activity and crater incandescence in the Voragine Crater at Etna on 15 November 2019. Photo by B. Behncke, taken by Tremestieri Etneo. Courtesy of INGV (Report 47/2019, ETNA, Bollettino Settimanale, 11/11/2019 - 17/11/2019, data emissione 19/11/2019).

Figure 290. Webcam images of summit crater activity during 26-29 November and 1 December 2019 at Etna. a) image recorded by the high-resolution camera on Montagnola (EMOV); b) and c) webcam images taken from Tremestieri Etneo on the southern slope of Etna showing summit incandescence; d) image recorded by the thermal camera on Montagnola (EMOT) showing summit incandescence at the NSEC. Courtesy of INGV (Report 49/2019, ETNA, Bollettino Settimanale, 25/11/2019 - 01/12/2019, data emissione 03/12/2019).

Frequent Strombolian explosions continued through December 2019 within the VOR-BN, NEC, and NSEC Craters with sporadic ash emissions observed in the VOR-BN and NEC. On 6 December, Strombolian explosions increased in the NSEC; webcam images showed incandescent pyroclastic material ejected above the crater rim. On the morning of 6 December a lava flow was observed from the base of the scoria cone in the VOR Crater that traveled toward the adjacent Bocca Nuova Crater. INGV reported that a new vent opened on the side of the saddle cone (NSEC) on 11 December and produced explosions until 14 December.

Activity during January-March 2020. On 9 January 2020 an aerial flight organized by RAI Linea Bianca and the state police showed the VOR Crater continuing to produce lava that was flowing over the crater rim into the BN Crater with some explosive activity in the scoria cone. Explosive Strombolian activity produced strong and distinct SO2 plumes (figure 291) and ash emissions through March, according to the weekly INGV reports, VONA notices, and satellite imagery. Several ash emissions during 21-22 January rose from the vent that opened on 11 December. According to INGV’s weekly bulletin for 21-26 January, the scoria cone in the VOR crater produced Strombolian explosions that increased in frequency and contributed to rapid cone growth, particularly the N part of the cone. Lava traveled down the S flank of the cone and into the adjacent Bocca Nuova Crater, filling the E crater (BN-2) (figure 292). The NEC had discontinuous Strombolian activity and periodic, diffuse ash emissions.

Figure 291. Distinct SO2 plumes drifting in multiple directions from Etna were visible in satellite imagery as Strombolian activity continued through March 2020. Top left: 21 January 2020. Top right: 2 February 2020. Bottom left: 10 March 2020. Bottom right: 19 March 2020. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Figure 292. a) A map of the lava field at Etna showing cooled flows (yellow) and active flows (red). The base of the scoria cone is outlined in black while the crater rim is outlined in red. b) Thermal image of the Bocca Nuova and Voragine Craters. The bright orange is the warmest temperature measure in the flow. Courtesy of INGV, photos by Laboratorio di Cartografia FlyeEye Team (Report 10/2020, ETNA, Bollettino Settimanale, 24/02/2020 - 01/03/2020, data emissione 03/03/2020).

Strombolian explosions continued into February 2020, accompanied by ash emissions and lava flows from the previous months (figure 293). During 17-23 February, INGV reported that some subsidence was observed in the central portion of the Bocca Nuova Crater. During 24 February to 1 March, the Strombolian explosions ejected lava from the VOR Crater up to 150-200 m above the vent as bombs fell on the W edge of the VOR crater rim (figure 294). Lava flows continued to move into the W part of the Bocca Nuova Crater.

Figure 293. Webcam images of A) Strombolian activity and B) effusive activity fed by the scoria cone grown inside the VOR Crater at Etna taken on 1 February 2020. C) Thermal image of the lava field produced by the VOR Crater taken by L. Lodato on 3 February (bottom left). Image of BN-1 taken by F. Ciancitto on 3 February in the summit area (bottom right). Courtesy of INGV; Report 06/2020, ETNA, Bollettino Settimanale, 27/01/2020 - 02/02/2020, data emissione 04/02/2020 (top) and Report 07/2020, ETNA, Bollettino Settimanale, 03/02/2020 - 09/02/2020, data emissione 11/02/2020 (bottom).

Figure 294. Photos of the VOR intra-crater scoria cone at Etna: a) Strombolian activity resumed on 25 February 2020 from the SW edge of BN taken by B. Behncke; b) weak Strombolian activity from the vent at the base N of the cone on 29 February 2020 from the W edge of VOR taken by V. Greco; c) old vent present at the base N of the cone, taken on 17 February 2020 from the E edge of VOR taken by B. Behncke; d) view of the flank of the cone, taken on 24 February 2020 from the W edge of VOR taken by F. Ciancitto. Courtesy of INGV (Report 10/2020, ETNA, Bollettino Settimanale, 24/02/2020 - 01/03/2020, data emissione 03/03/2020).

During 9-15 March 2020 Strombolian activity was detected in the VOR Crater while discontinuous ash emissions rose from the NEC and NSEC. Bombs were found in the N saddle between the VOR and NSEC craters. On 9 March, a small scoria cone that had formed in the Bocca Nuova Crater and was ejecting bombs and lava tens of meters above the S crater rim. The lava flow from the VOR Crater was no longer advancing. A third scoria cone had formed on 13 March NE in the main VOR-BN complex due to the Strombolian explosions on 29 February. Another lava flow formed on 13 March, accompanied by an increase in seismicity. The weekly report for 16-22 March reported Strombolian activity detected in the VOR Crater and gas-and-steam and rare ash emissions observed in the NEC and NSEC (figure 295). Explosions in the Bocca Nuova Crater ejected spatter and bombs 100 m high.

Figure 295. Map of the summit crater area of Etna showing the active vents and lava flows during 16-22 March 2020. Black hatch marks indicate the crater rims: BN = Bocca Nuova, with NW BN-1 and SE BN-2; VOR = Voragine; NEC = North East Crater; SEC = South East Crater; NSEC = New South East Crater. Red circles indicate areas with ash emissions and/or Strombolian activity, yellow circles indicate steam and/or gas emissions only. The base is modified from a 2014 DEM created by Laboratorio di Aerogeofisica-Sezione Roma 2. Courtesy of INGV (Report 13/2020, ETNA, Bollettino Settimanale, 16/03/2020 - 22/03/2020, data emissione 24/03/2020).

Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Information Contacts: Sezione di Catania - Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/it/); Toulouse Volcanic Ash Advisory Center (VAAC), Météo-France, 42 Avenue Gaspard Coriolis, F-31057 Toulouse cedex, France (URL: http://www.meteo.fr/aeroweb/info/vaac/); 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); Boris Behncke, Sonia Calvari, and Marco Neri, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: https://twitter.com/etnaboris, Image at https://twitter.com/etnaboris/status/1183640328760414209/photo/1).

Merapi is a highly active stratovolcano located in Indonesia, just north of the city of Yogyakarta. The current eruption episode began in May 2018 and was characterized by phreatic explosions, ash plumes, block avalanches, and a newly active lava dome at the summit. This reporting period updates information from October 2019-March 2020 that includes explosions, pyroclastic flows, ash plumes, and ashfall. The primary reporting source of activity comes from Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG, the Center for Research and Development of Geological Disaster Technology, a branch of PVMBG) and Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM).

Some ongoing lava dome growth continued in October 2019 in the NE-SW direction measuring 100 m in length, 30 m in width, and 20 m in depth. Gas-and-steam emissions were frequent, reaching a maximum height of 700 m above the crater on 31 October. An explosion at 1631 on 14 October removed the NE-SW trending section of the lava dome and produced an ash plume that rose 3 km above the crater and extended SW for about 2 km (figures 90 and 91). The plume resulted in ashfall as far as 25 km to the SW. According to a Darwin VAAC notice, a thermal hotspot was detected in HIMAWARI-8 satellite imagery. A pyroclastic flow associated with the eruption traveled down the SW flank in the Gendol drainage. During 14-20 October lava flows from the crater generated block-and-ash flows that traveled 1 km SW, according to BPPTKG.

Figure 90. An ash plume rising 3 km above Merapi on 14 October 2019.

Figure 91. Webcam image of an ash plume rising above Merapi at 1733 on 14 October 2019. Courtesy of BPPTKG via Jaime S. Sincioco.

At 0621 on 9 November 2019, an eruption produced an ash plume that rose 1.5 km above the crater and drifted W. Ashfall was observed in the W region as far as 15 km from the summit in Wonolelo and Sawangan in Magelang Regency, as well as Tlogolele and Selo in Boyolali Regency. An associated pyroclastic flow traveled 2 km down the Gendol drainage on the SE flank. On 12 November aerial drone photographs were used to measure the volume of the lava dome, which was 407,000 m3. On 17 November, an eruption produced an ash plume that rose 1 km above the crater, resulting in ashfall as far as 15 km W from the summit in the Dukun District, Magelang Regency (figure 92). A pyroclastic flow accompanying the eruption traveled 1 km down the SE flank in the Gendol drainage. By 30 November low-frequency earthquakes and CO2 gas emissions had increased.

Figure 92. An ash plume rising 1 km above Merapi on 17 November 2019. Courtesy of BPPTKG.

Volcanism was relatively low from 18 November 2019 through 12 February 2020, characterized primarily by gas-and-steam emissions and intermittent volcanic earthquakes. On 4 January a pyroclastic flow was recorded by the seismic network at 2036, but it wasn’t observed due to weather conditions. On 13 February an explosion was detected at 0516, which ejected incandescent material within a 1-km radius from the summit (figure 93). Ash plumes rose 2 km above the crater and drifted NW, resulting in ashfall within 10 km, primarily S of the summit; lightning was also seen in the plume. Ash was observed in Hargobinangun, Glagaharjo, and Kepuharjo. On 19 February aerial drone photographs were used to measure the change in the lava dome after the eruption; the volume of the lava had decreased, measuring 291,000 m3.

Figure 93. Webcam image of an ash plume rising from Merapi at 0516 on 13 February 2020. Courtesy of MAGMA Indonesia and PVMBG.

An explosion on 3 March at 0522 produced an ash plume that rose 6 km above the crater (figure 94), resulting in ashfall within 10 km of the summit, primarily to the NE in the Musuk and Cepogo Boyolali sub-districts and Mriyan Village, Boyolali (3 km from the summit). A pyroclastic flow accompanied this eruption, traveling down the SSE flank less than 2 km. Explosions continued to be detected on 25 and 27-28 March, resulting in ash plumes. The eruption on 27 March at 0530 produced an ash plume that rose 5 km above the crater, causing ashfall as far as 20 km to the W in the Mungkid subdistrict, Magelang Regency, and Banyubiru Village, Dukun District, Magelang Regency. An associated pyroclastic flow descended the SSE flank, traveling as far as 2 km. The ash plume from the 28 March eruption rose 2 km above the crater, causing ashfall within 5 km from the summit in the Krinjing subdistrict primarily to the W (figure 94).

Figure 94. Images of ash plumes rising from Merapi during 3 March (left) and 28 March 2020 (right). Images courtesy of BPPTKG (left) and PVMBG (right).

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities during historical time.

Information Contacts: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Center for Research and Development of Geological Disaster Technology (URL: http://merapi.bgl.esdm.go.id/, Twitter: @BPPTKG); 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/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/, Twitter: https://twitter.com/BNPB_Indonesia); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); 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/); Jamie S. Sincioco, Phillipines (Twitter: @jaimessincioco, Image at https://twitter.com/jaimessincioco/status/1227966075519635456/photo/1).

The first recorded eruption in 30 years at Russia's Chirpoi volcano was initially detected on 11 November 2012 by MODIS infrared satellite data and captured by the MODVOLC thermal alert system. The Sakhalin Volcanic Eruption Response Team (SVERT) reported satellite images that detected thermal anomalies over Snow, a volcanic crater on the S end of Chirpoi Island, beginning on 20 November 2012 (BGVN 38:12), which they interpreted as a possible lava flow on the SE flank. Sparse satellite observations by SVERT, MIROVA and MODVOLC thermal anomaly information, a single report from the Tokyo Volcanic Ash Advisory Center (VAAC), and a site visit to this remote location in the Kuril Islands in the western Pacific Ocean together suggest nearly continuous activity at Snow through mid-October 2016.

Activity during November 2012-April 2013. Continuous reports of activity between November 2012 and April 2013 began with strong MODVOLC thermal anomalies from MODIS satellite data first recorded on 11 November local time, followed by a report of thermal anomalies detected from SVERT on 20 November. Strong thermal anomalies were reported by MODVOLC for 12 days during November and nine days during December 2012, after which they did not appear again until July 2013. However, SVERT reported thermal anomalies in satellite data almost weekly through 26 April 2013. They also observed steam-and-gas emissions in satellite data a number of times between 15 December 2012 and 5 March 2013.

Activity during July 2013-June 2014. After about a 10 week break between thermal anomaly observations, the MODVOLC pixels reappeared on 8 July 2013, and SVERT reported a thermal anomaly on 14 July 2013 suggesting a new period of lava effusion. The MODVOLC anomalies were intermittent with only three in July, one each in August and September, and two in October 2013; they then disappeared until March 2014. A single MODVOLC thermal anomaly was recorded on 10 March 2014, one appeared on 2 June and two appeared on 25 June 2014.

SVERT reported anomalies twice in July 2013, three times in August and once on 1 September before picking up again in November. SVERT reported thermal anomalies every week in November 2013, and most weeks through the first week in May 2014. After weak anomalies during 2-4 June 2014, SVERT inferred cooling lava flows and lowered the Alert Level from Yellow to Green.

Steam-and-gas emissions were reported by SVERT only between 23 July and 12 August 2013, and not again until late October. Gas-and-steam emissions were common between 22 October and 25 November 2013 when a plume was observed in satellite imagery drifting 90 km SE, after which plumes were not observed until 15 March 2014. Twice in late March (20 and 27) steam-and-gas plumes were detected drifting SE (150 and 50 km). After 13 April 2014, plumes were not detected again until September.

Activity during August 2014-October 2016. Although SVERT kept the Alert Level at Green until 4 September 2014 when they raised it back to Yellow, MODVOLC thermal alert pixels in late June (two on the 25th) and on 10 August, suggest possible continued activity during the summer. When skies were clear, SVERT again detected thermal anomalies in satellite data beginning on 1 September 2014 and continuing most weeks until 8 June 2015. MODVOLC recorded thermal anomalies on 2 and 22 September, and 22 October 2014, but then was quiet until a strong signal reappeared in April 2015 with six days of multiple anomalies recorded during the month, and five days with anomalies in May. During this interval from September 2014 to June 2015, steam-and-gas plumes were reported twice each in September 2014, February, March, and April 2015, and on 25 May 2015.

While no data is available from SVERT between 9 June and 11 November 2015, the Aviation Color Code remained at Yellow, and single MODVOLC thermal alert pixels were recorded on 28 June, 19 and 30 July, two on 7 September, and one each on 5 October, 3 November, and 19 November 2015, suggesting some type of continued heat source such as a lava flow. In addition, MIROVA records for 2015 provide the strongest evidence for ongoing low-to-moderate volcanic activity throughout 2015 (figure 2).

Figure 2. Chirpoi thermal anomaly information from MIROVA for 2 Feb 2015 through 31 December 2016 showing Log Radiative Power measured from MODIS infrared satellite data. Continuous thermal anomalies throughout the period suggest an ongoing heat source such as a lava flows. Vertical axis VRP is Volcanic Radiative Power. Courtesy of MIROVA.

Visual confirmation of an effusive eruption at Chirpoi was made in October 2015. The website Volcano Discovery reported that "Passengers on board a Russian cruise ship (Ponant) documented the recent … eruption of Snow volcano. When passing the island in October 2015, lava flows were actively reaching the sea, creating spectacular littoral explosions." (figure 3). A video of the event from the cruise ship is also posted on the website.

Figure 3. Explosion of steam and rock fragments as lava from Snow volcano on Chirpoi Island enters the sea. Taken by a passenger on the Russian cruise ship Ponant, 8 October 2015. See complete video for additional imagery. Courtesy of Volcano Discovery, 2015.

SVERT reports were available again beginning in November 2015 and they reported that satellite images revealed thermal anomalies almost weekly from 11 November through 10 August 2016. They lowered the Alert Level to Green on 29 August 2016. MODVOLC thermal anomaly data was sparse in 2016 with only three reports of single anomalies on 5 February, 20 May, and 12 June 2016. Reports of steam-and-gas plumes observed in satellite imagery from SVERT were made on 12 and 14 November 2015, 24 March, and 20 and 23 April 2016. A plume that may have contained minor ash was observed by SVERT in satellite data drifting SW on 16 July, and one drifting 90 km N was noted during 22-24 July.

The Tokyo VAAC reported a possible eruption observed on satellite imagery at 1300 UTM on 6 March 2016 with a plume rising to 6.1 km altitude and drifting E. MIROVA data for 2016 again seems to confirm ongoing low to moderate thermally anomalous activity at Chirpoi until the middle of October when Radiative Power levels drop below 0.5 Watts VRP (figure 2).

Geologic Background. Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. The symmetrical Cherny volcano, which forms the central cone of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.

Information Contacts: Sakhalin Volcanic Eruption Response Team (SVERT), Institute of Marine Geology and Geophysics, Far Eastern Branch, Russian Academy of Science, Nauki st., 1B, Yuzhno-Sakhalinsk, Russia, 693022 (URL: http://www.imgg.ru/en/, http://www.imgg.ru/ru/svert/reports/); 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/, http://modis.higp.hawaii.edu/cgi-bin/modisnew.cgi); 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/); Volcano Discovery (URL: http://www.volcanodiscovery.com/chirpoi/news/55254/Chirpoi-volcano-Kurile-Islands-Russia-video-of-lava-entering-the-sea.html); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

An ash explosion from Kanlaon on 24 November 2015 was the start of activity that included intermittent ash emissions through December and during 29-31 March 2016 (BGVN: 4014). That activity was followed by decreasing tremor and steam plumes rising to as high as 800 during the first days of April 2016. A short series of explosions on 18 June 2016 were the last ash emissions through 2016, based on Philippine Institute of Volcanology and Seismology (PHIVOLCS) reports. The Alert Level remained at 1 (on a scale of 0-5) throughout the reporting period, indicating low level of volcanic unrest.

PHIVOLCS reported that ground deformation measurements from continuous GPS data as of 2 June 2016 indicated slight inflation of the edifice since December 2015. Weak to moderate emission of white steam plumes that rose 540 m during 15-17 June and drifted SW and NW.

A series of three eruptive events occurred on 18 June, beginning at 0919 and lasting 27 minutes. These events were recorded by the seismic monitoring network as consecutive explosion-type earthquakes that lasted 30, 42, and 29 seconds, respectively. The first event, a steam-and-gas explosion, generated a light gray-to-white ash plume that initially rose 1.5 km above the crater and then later to 3 km (figure 3). The second event, an ash eruption immediately following the first event, produced a dense black ash plume that rose 500 m. Lastly, a grayish ash plume rose 500 m. Minor ashfall was reported to the W in the barangays of Ara-al, San Miguel, and Yubo in La Carlota City (14 km W), Sag-ang in La Castellana (16 km SW), and Ilijan in Bago City (30 km NW). A diffuse sulfur odor was detected in Ara-al.

Figure 3. Photo sequence showing eruption plumes from Kanlaon at 0919 on 18 June 2016. Courtesy PHIVOLCS.

PHIVOLCS reported that during 20, 22-23, and 25-26 June white steam plumes rose as high as 800 m and drifted WNW, NW and SW; wispy steam plumes were observed on 27 June. Starting at 1640 on 23 June the seismic network recorded a 4-minute-long, explosion-type signal; weather clouds prevented visual observations of the summit area.

White plumes were again seen during 20-25 July. On 20 July plumes were a dirty-white color; on 21-22 they were of white steam; and on 25 July they rose 200 m and drifted NW and SW. Sulfur dioxide (SO2) emitted at the active vent averaged 234 tonnes/day on 21 July.

Ground deformation data from continuous GPS measurements as of 3 September 2016 indicated no significant change of the edifice since August 2016.

Geologic Background. Kanlaon volcano (also spelled Canlaon), the most active of the central Philippines, forms the highest point on the island of Negros. The massive andesitic stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller, but higher, historically active vent, Lugud crater, to the south. Historical eruptions, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P. Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/).

After two explosions at Langila produced ash plumes that rose to 1.5 and 2.1 km in early December 2012 (BGVN 41.01), no further information about the volcano's activity was available from the Rabaul Volcano Observatory or the Darwin VAAC until April 2016. This report discusses two new eruptions in 2016, one during 2 April-13 May and the other during 3 November-24 December. Observations of ash plumes continued into mid-January 2017.

Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were occasionally detected after 2012. During 2013, seven anomalies were reported during 23 October-1 December (4 pixels on 25 October); during 2014-2015, a possible anomaly was identified on 23 August 2014 NE of the crater and thus probably not associated with volcanic activity.

During 2016, the Darwin VAAC reported the ejection of several ash plumes during 2 April-13 May and 3 November-24 December (table 3). Most plumes rose between 2-3.3 km in altitude. MODVOLC thermal alerts were also seen during those two periods, with six anomalies during April and May, and one reported in November During 20-27 December 2016, five thermal anomalies were reported (most with more than one pixel). Two alert pixels in August were weak and somewhat E of the volcano, and probably not associated with activity.

Table 3. Ash plumes from Langila reported during April-May and November-December 2016. Observations are based on analyses of satellite imagery, ground observations by the Rabaul Volcano Observatory, and wind data; dates are based on local time. Courtesy of the Darwin VAAC.

The Mirova (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, also detected occasional hotspots during 2016 (figure 5). Most occurred during April-May and November-December, but a few intermittent anomalies were noted every month during June-October as well. The heat radiated by the volcanic activity (or Volcanic Radiative Power, as measured in watts) was mostly less than 0.5 W.

Figure 5. Plot of MIROVA thermal anomaly MODIS data during 7 January 2016-6 January 2017. Periods of more frequent anomalies in April-May and November-December 2016 correspond to reports of ash plumes. Courtesy of MIROVA.

Geologic Background. Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite basaltic-andesitic cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the north and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m.

Information Contacts: 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/); Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; 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/, http://modis.higp.hawaii.edu/); 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/).

Between 1996 and 2011 there were about 14 seismic swarms at Momotombo, along with fumarolic activity, and an explosion in 2006 (BGVN 37:02). According to the Instituto Nicaragüense de Estudios Territoriales (INETER), explosive activity that generated ash plumes resumed on 1 December 2015 and ended on 8 April 2016. The number of daily explosions increased beginning on 12 February 2016, with very high counts in the first half of March (figure 15).

Figure 15. Histogram of number of daily explosions between 1 December 2015 and 3 April 2016. The total number of explosions with ash emissions was 409 (438 overall), with 314 reported in March 2016 alone (76 percent of total); 88 explosions were detected during 1 December 2015-1 March 2016. The graph does not show the few small explosions during the week subsequent to 3 April 2016. Courtesy of INETER.

Activity during December 2015-January 2016. According to the Instituto Nicaragüense de Estudios Territoriales (INETER), an explosion at 0749 on 1 December 2015 generated a gas-and-ash plume that rose 1 km above the crater and drifted SW. Additional explosions at 0817, 0842, and 0855 generated ash plumes that rose 300 m. Gas emissions were visible the rest of the day. The Sistema Nacional para la Prevención, Mitigación y Atención de Desastres (SINAPRED) reported that during 1-2 December, explosions ejected incandescent tephra, and a slow-moving lava flow on the N flank was observed. According to a news report (La Prensa) that interviewed INETER officials, ashfall was reported in nearby communities to the W and SW, including La Concha (40 km SSE), Los Arcos, Flor de la Piedra, La Paz Centro, and Leóin. Some families in La Paz Centro (17 km SW) self-evacuated.

Based on satellite and webcam observations, and seismic data, the Washington Volcanic Ash Advisory Center (VAAC) reported that during 2-3 December 2015, ash plumes rose to an altitude of 2.4 km and drifted 90-225 km NW and WNW.

According to INETER and SINAPRED reports, activity continued through 10 December 2015. Fieldwork revealed a small, incandescent, circular crater halfway up the E flank that was fuming during the morning of 6 December. An explosion on 7 December destroyed part of the crater. On 10 December, SINAPRED reported that material had been accumulating in the crater since the beginning of the eruption on 1 December. Seismicity during 9-14 December was low and stable.

INETER reported that during 29-30 December 2015, no explosions were detected, though Real-time Seismic-Amplitude Measurements (RSAM) continued at moderate-to-high levels.

Three gas-and-ash explosions on 2 January 2016 (at 1333, 1426, and 1434) were noted in INETER and SINAPRED reports which excavated the remaining parts of the lava dome that had been emplaced about a month earlier. An ash plume rose 500 m above the crater, drifted S and SW, and caused ashfall in Puerto Momotombo (9 km WSW). Possible ash plumes from an explosion at 2129 were hidden by darkness. At 0420 on 3 January, an explosion ejected lava bombs 2 km away and caused ashfall in La Paz Centro. Lava flows had advanced as far as 2 km down the NE flank.

INETER reported that at 1209 on 12 January 2016, a large explosion ejected incandescent material onto the flanks and generated an ash plume that rose 4 km above the crater. Tephra was deposited on the E, NE, N, and NW flanks. Ash plumes drifted downwind and caused ashfall in the communities of Flor de Piedra, Amatistán, Guacucal (40 km N), La Palma, Puerto Momotombo (10 km WSW), La Sabaneta, Mira Lago, Asentamiento Miramar, Pancasán, René Linarte, Raúl Cabezas, and Betania. At around 0500 on 15 January, strong volcanic tremor was accompanied by small explosions in the crater; ejected ash and incandescent tephra were deposited on the W flank. Seismicity decreased during 16-17 January.

According to INETER, during 20-21 January both RSAM values and emissions were low. Volcanic tremor increased at 0900 on 22 January, causing RSAM values to rise to high levels. There were no emission changes. INETER recommended that the public stay at least 6 km away from the volcano.

INETER reported that during 26-29 January, RSAM values were at low to moderate levels, and gas emissions were at moderate levels. Crater incandescence from high-temperature gas emissions was observed at night during 26-27 January. A Strombolian explosion at 0344 on 30 January ejected tephra onto the E, NE, N, and NW flanks, and produced gas emissions. At 0529 on 31 January, another explosion also ejected gas, ash, and incandescent material. Ashfall was reported in the nearby communities of Boqueron, Puerto Momotombo, and La Sabaneta. Moderate levels of gas emissions drifted SW towards Puerto Momotombo.

Activity during February-April 2016. During 4-5 and 7-8 February, both RSAM values were low to moderate and emissions were at moderate levels. INETER reported moderate levels of gas emissions on 10 February; volcanic tremor and gas emissions increased to moderate-to-high levels the next day. An explosion on 12 February produced small ash emissions and ejected incandescent material onto the N and SE flanks. An explosion at 1305 on 15 February generated an ash plume that rose 2 km above the crater and ejected incandescent tephra onto the N and NE flanks.

INETER reported that during 16-17 February, two explosions accompanied by tremor produced ash emissions and ejected incandescent material onto the flanks. The first and largest explosion (at 0344) ejected incandescent tephra 800 m above the crater. RSAM values were at low-to-moderate levels. Based on webcam views and satellite images, the Washington VAAC reported that on 19 February, ash emissions rose to an altitude of 3.6 km and drifted SW and WSW. The next day, ash emissions drifted SW. On 21 February ash plumes drifted about 80 km W and 25 km E.

During 19 February-1 March, explosions were detected daily. Explosions produced ash plumes and ejected incandescent material onto the N, NE, E, and SE flanks. Ash plumes rose 1.7-2.3 km above the crater and drifted SW during 21-22 February; gas-and-ash plumes rose 1.8 km on 24 February; an ash plume rose 1 km on 25 February and a small gas-and-ash plume rose 300 m on 26 February. A pyroclastic flow traveled 3.5 km down the N and NW flanks during 23-24 February. Explosions on 27 February ejected tephra 300 m above the crater.

At 0646 on 1 March, explosions ejected gas and incandescent tephra, and an ash plume that rose 1.2 km lasted 16 minutes, causing the plume to widen and darken the sky. According to INETER, 53 small explosions during 2-3 March generated weak gas plumes that rose 300 m above the crater. On 3 March, some explosions produced ash plumes that drifted W and SW. RSAM values were at low to moderate levels. SINAPRED reported that during 5-6 March, there were 78 explosions for a total of 279 explosions detected since 1 December 2015. One of the most significant explosions occurred on 6 March. The next day gas-and-ash plumes rose as high as 1 km above the crater.

On 28 March, SINAPRED reported that 38 explosions, detected over a period of 24 hours, ejected gas-and-ash plumes and incandescent tephra. The strongest event occurred at 1140 on 27 March and generated a plume that rose 1 km.

SINAPRED reported that on 2 April, explosions produced gas-and-ash plumes and ejected incandescent tephra. According to INETER, three explosions during 5-6 April ejected incandescent material onto the flanks and produced gas-and-ash plumes that rose 500 m above the crater. During 6-7 April there were 27 small explosions. The explosions ejected some incandescent material and generated ash plumes that rose 200 m and drifted SW. RSAM values were low during 5-12 April.

Monthly INETER reports did not indicate any explosive activity after 8 April 2016. The August 2016 report indicated that seismicity was low, with only five volcano-tectonic earthquakes. The RSAM in August was a low 30 units.

Thermal anomalies during the 2015-16 eruption. Many thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were observed between 2-6 December 2015, primarily on the ENE flank. Subsequently, one anomaly was observed on 1 February, 2 February, and 15 February 2016. A weak possible hotspot on the E flank was also observed on 19 February, but it was slightly S of the previous hotspots.

The Mirova (Middle InfraRed Observation of Volcanic Activity) system, also based on analysis of MODIS data, detected several anomalies within 5 km of the crater during March 2016, but none thereafter through 2016. The heat radiated by the volcanic activity (or Volcanic Radiative Power, as measured in watts) was mostly less than 0.5 watts.

Before this latest activity, a weak hotspot was also detected by MODVOLC on 7 March 2012 near the N rim of the crater, and on 19 June 2014, somewhat further down the E flank than most of the other events; neither event may have been associated with volcanism; no volcanic activity was reported on those days.

Geologic Background. Momotombo is a young stratovolcano that rises prominently above the NW shore of Lake Managua, forming one of Nicaragua's most familiar landmarks. Momotombo began growing about 4500 years ago at the SE end of the Marrabios Range and consists of a somma from an older edifice that is surmounted by a symmetrical younger cone with a 150 x 250 m wide summit crater. Young lava flows extend down the NW flank into the 4-km-wide Monte Galán caldera. The youthful cone of Momotombito forms an island offshore in Lake Managua. Momotombo has a long record of Strombolian eruptions, punctuated by occasional stronger explosive activity. The latest eruption, in 1905, produced a lava flow that traveled from the summit to the lower NE base. A small black plume was seen above the crater after a 10 April 1996 earthquake, but later observations noted no significant changes in the crater. A major geothermal field is located on the south flank.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://webserver2.ineter.gob.ni/vol/dep-vol.html); Sistema Nacional para la Prevención, Mitigación y Atención de Desastres (SINAPRED), Edificio SINAPRED, Rotonda Comandante Hugo Chávez 50 metros al Norte, frente a la Avenida Bolívar, Managua, Nicaragua (URL: http://www.sinapred.gob.ni/); 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: http://www.ospo.noaa.gov/Products/atmosphere/vaac/, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); 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/); 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/); La Prensa (Nicaragua) (URL: http://www.laprensa.com.ni/).

Nyiragongo holds one of the world's largest lava lakes, having been observed since at least 1971 (CSLP 21-71). Lava flows in 1977 and 2002 had deadly consequences for the city of Goma, which lies about 15 km S of the summit. The last Bulletin (BGVN 39:04) summarized observations made by a team of scientists that visited the volcano during 30 May-9 June 2011, and Toulouse Volcanic Ash Advisory Center (VAAC) notices posted in July 2012. This report covers activity from November 2011 through December 2016. Ground reports of activity are infrequent, though there are intermittent tourist expeditions, and a visit by scientists in March 2016 provided visual observations detailing changes in the crater and vent morphology.

Excellent pictures of the lava lake within the crater were taken in June 2010 by photographer Olivier Grunewald, while on an expedition to the volcano with observatory scientists doing fieldwork. These images, 28 total, were provided by Nelson (2011) for a news article; three are shown below (figures 54-56).

Figure 54. The lava lake within the Nyiragongo crater, June 2010. Photo by Olivier Grunewald in Nelson (2011).

Figure 55. Close-up daytime view of lava overflowing from the elevated active pit within the summit crater, June 2010. Note person for scale at lower left. Photo by Olivier Grunewald in Nelson (2011).

Figure 56. Night view from the crater rim of lava overflowing from the elevated active pit within the summit crater, June 2010. Photo by Olivier Grunewald in Nelson (2011).

Emissions and thermal anomalies. A nearly daily record of thermal alerts identified from the MODIS Agua and Terra satellite sensors has been generated by MODVOLC since 2002; the MODVOLC and MIROVA systems recorded nearly daily thermal anomalies during 2015 and at least through December 2016.

According to NASA's Earth Observatory, a satellite image acquired on 15 November 2011 showed heat coming from the active lava lake. The Toulouse VAAC reported that, according to a Volcano Observatory Notices for Aviation (VONA) issued by OVG (Observatoire Volcanologique de Goma), a gas plume composed mostly of sulfur dioxide rose from the crater on 1 November 2012. Another satellite image, acquired on 29 July 2013 and analyzed by NASA's Earth Observatory, again showed incandescence coming from the active lava lake in the summit crater; a diffuse blue plume drifted N.

A satellite image from 29 January 2014 showed a gas-and-steam plume rising from Nyiragongo. On 9 February 2015, clear skies permitted a view from space of plumes venting from Nyamuragira (figure 57, top) and Nyiragongo (figure 57, bottom) volcanoes.

Figure 57. The natural-color satellite image above was acquired on 9 February 2015 by the Operational Land Imager (OLI) instrument on Landsat 8, showing a broad view of the region, with Nyamuragira to the N and Nyiragongo to the S, separated by a distance of about 15 km. Courtesy of NASA Earth Observatory.

New vent in crater, February 2016. Activity intensified on 28 February 2016, prompting OVG to dispatch a team of scientists to the crater. Starting at 0400 on 29 February, local residents began to hear frequent rumblings coming from the volcano almost every minute. These were likely caused by the opening of a new vent (observed the next day) and associated rockfalls inside the crater. During a 1-2 March field expedition, the scientists observed the new eruptive vent (figure 58), located at the NE end of the lowest crater terrace, outside the active lava lake (which had been in place since 2002) and just at the base of the near-vertical crater walls. The vent sits on the E-trending fracture zone that connects the summit vent with the prominent flank cone Baruta to the NE of the main edifice, near the village of Kibumba. Photos in the report suggest that the new vent sits atop a small spatter cone. Fresh lava flows had pooled onto the crater floor around the cone.

Figure 58. A new vent that had recently emerged on the E part of Nyiragongo's floor (terrace three) was first observed by OVG scientists on 1 March 2016. Photo courtesy of OVG.

Observers during a 10-11 March field expedition noted that activity in the new vent consisted in pulsating lava fountains and Strombolian bursts which ejected material of a few tens of meters high. Lava flows from the new vent extended around the central pit on 11 March (figure 59). Activity in the lava lake was intense; lava fountains were active in the N and E parts of the lake. Both the lava lake and crater vent were producing gas emissions (figure 60).

Figure 59. A view of the Nyiragongo summit crater on the night of 11-12 March 2016. The new vent on the E crater floor (right) produced lava flows that extended around the main lava lake.

Figure 60. A daytime view of the Nyiragongo summit crater during 11-12 March 2016. Gas emissions from the new vent on the E crater floor (right) and from the lava lake were visible. The second and third terraces are visible in this wider view.

On 26 March and 8 April 2016, the mainly effusive activity from the new vent continued with little change. Lava flows had surrounded the central pit (containing the main lava lake), covered most of the third terrace, and cascaded into the central vent at multiple locations.

A report from OVG on 12 April 2016 noted that activity had declined since 6 April 2016, and that the level of the lava lake had dropped. A report dated 17 April stated that some volcanic earthquakes had been located within 5 km E and 10-15 km N of the crater; continuous volcanic tremor was recorded during 0200-0400 on 17 April. In a photo dated 19 April the incandescent vent atop a spatter cone was visible. According to Volcano Discovery, local mountain guides reported that as of 30 May, no more lava flows were being produced from the vent, although bubbling lava was visible.

Ongoing activity through December 2016. Social media accounts and photos from a few tourist expeditions showed that the lava lake within the summit crater remained active during August-November 2016. Infrared data from MODIS instruments confirmed this persistent activity, with almost daily anomalies, through the end of December 2016.

Information from a weekly bulletin produced by the Goma Volcano Observatory, not available online, was reported by Radio Kivu. That report, for 27 December-2 January 2017, noted there was incandescence visible during 30-31 December, and that lava flows had overflowed the lake into the rest of the crater, accompanied by explosions and fountaining. A persistent gas plume can be seen during the day, which typically blows to the west.

Research on January 2002 eruption. In a recent article by Wauthier and others (2012), and summarized by Morton (2016), researchers reported finding evidence for linkage between the deadly January 2002 eruption (BGVN 26:12 and later) and a magnitude-6.2 earthquake eight months afterwards, centered 20 km S in the Lake Kivu region, partially destroying the town of Kalehe. Using satellite radar data (InSAR – Interferometric Synthetic Aperature Radar) to analyze ground deformation between the volcano and the lake before and after both the eruption and the earthquake, they inferred the formation of 20-km-long dike intrusion (figure 61, along the pink line between Nyiragongo and Lake Kivu).

Figure 61. (a) Shaded relief topographic map of the Goma area and Lake Kivu. (b) Inset shows the region between Nyiragongo and Lake Kivu; the Goma and Gisenyi urban areas highlighted in white. From Wauthier and others (2012).

References: Morton, M. C., 2016 (May/June), Double trouble: Volcanic eruption leads to strong earthquake eight months later, Earth, American Geosciences Institute, v.61, no. 5&6, p. 33 (www.earthmagazine.org).

Nelson, P., 2011 (28 February), Nyiragongo Crater: Journey to the Center of the World, boston.Com (URL: http://archive.boston.com/bigpicture/2011/02/nyiragongo_crater_journey_to_t.html). Photos by Olivier Grunewald.

Wauthier, C., Cayol, V., Kervyn, F., and d'Oreye, N., 2012 (May), Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis, Journal of Geophysical Research, Solid Earth, Geodesy and Gravity/Tectonophysics, v. 117, issue B5, 36 p.

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 (Goma Volcano Observatory), Goma, North Kivu, DR Congo; 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/); MIROVA - Middle InfraRed Observation of Volcanic Activity, A near real time volcanic hot-spot detection system based on the analysis of MODIS ( Moderate Resolution Imaging Spectroradiometer) data, a collaborative project between the Universities of Turin and Florence (Italy) (URL: http://www.mirovaweb.it/); Tom Pfeiffer, Volcano Discovery (URL: https://www.volcanodiscovery.com/nyiragongo/news); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Radio Kivu, Goma, North Kivu, DR Congo (URL: http://www.radiokivu1.org/page/article.php?action=articleread&tokena=1432).

An eruption at Rinjani that lasted two months, between 25 October and 24 December 2015 (BVGN 41:08) included ash plumes rising to 6 km altitude and lava flows from the Barujari cone that reached the Segara Anak lake within the caldera. A new eruption that began on 1 August 2016 generated ash plumes to about 10 km altitude. After another period of quiet, small-scale explosive activity on 27 September stranded a number of trekkers on the slopes and caused the Alert level to be raised to 2. No further activity was reported in 2016.

Based on satellite and pilot observations, the Darwin VAAC reported that an eruption on 1 August 2016 generated an ash plume that rose to an altitude of 9.8 km altitude and drifted S. The ash plumes were first visible in satellite images at 1150, and according to the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as the Centre for Volcanology and Geological Hazard Mitigation), passengers aboard a passing aircraft saw ash plumes rising 2 km above the crater (figure 27). The National Agency for Disaster Management (BNPB) noted that the Lombok International Airport closed at 1655 and was scheduled to reopen at 1000 the next day. Later on 1 August ash plumes rose to altitudes of 4.3-6.1 km altitude and drifted S, SW, and W. No plumes were visible at 1730; conditions had returned to normal levels, although BNPB warned that the public should stay at least 1.5 km away from the volcano.

Figure 27. Photo taken by an airline passenger of the explosive eruption at Rinjani on 1 August 2016. The plume was described as rising about 2 km above the crater. Image has been color adjusted to enhance contrast. Courtesy of PVMBG.

PVMBG reported that at 1445 on 27 September a small explosive eruption at Barujari Crater produced an ash plume rose that rose 2 km above the crater and drifted WSW. The eruption was preceded by an increase in seismicity, but the number and amplitude of the events were insignificant. The Alert Level was raised to 2, and the public was warned not to approach the crater within a 3-km radius.

Based on data from the Mount Rinjani National Park, BNPB reported that as many as 1,023 tourists were on Rinjani when it erupted on 27 September; officially only 464 people were registered to make the 3-day trek to the volcano and back. Officials began the evacuation of tourists that day.

The Jakarta Post reported on 1 October that the West Nusa Tenggara Disaster Mitigation Agency (BPBD NTB) had called on representatives of foreign countries to file a report if they had citizens still missing in the climbing area. The agency made the request following reports that 44 tourists had not yet returned from climbing the mountain. BPBD NTB head Muhammad Rum said it was possible that the climbers had returned, but had not yet been recorded, or had not passed through either of the two official entrances. The Jakarta Post reported on 5 December 2016 that hiking routes were once again open.

Geologic Background. Rinjani volcano on the island of Lombok rises to 3726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the west side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak (Samalas) caldera. The caldera formed during one of the largest Holocene eruptions globally in 1257 CE, which truncated Samalas stratovolcano. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the east end of the caldera. Historical eruptions dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Centre for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); 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/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Jakarta Post (URL: http://www.thejakartapost.com/).

An eruption at Sheveluch has been ongoing since 1999, and the activity there was previously described through August 2014 (BGVN 39:08). During 1 September 2014-28 February 2015 the same type of activity prevailed, with periods of strong explosions producing ash plumes as high as 11 km altitude. Most of the following data comes from Kamchatka Volcanic Eruption Response Team (KVERT) reports. Views of the volcano are often obscured by clouds.

KVERT reported that the explosive and effusive eruption continued into September 2014 through at least the end of February 2015. Activity was dominated by lava dome growth on the SE flank (N flank after mid-September), moderate ash explosions, fumarolic activity, and hot avalanches. According to KVERT, satellite data showed a thermal anomaly over the dome most days, when weather permitted observation. However, few MODVOLC alerts about MODIS thermal anomalies were recorded during the reporting period: two in September 2014, one in November, one in December, three in January 2015, and two in February.

Occasional strong explosions were reported by KVERT that produced ash plumes that rose as high as 11.5 km and drifted mostly in a northerly and easterly direction (NW to E). Strong explosions were recorded 2-3 times per month during September-November 2014, and about seven times per month during December 2014-February 2015. The Alert Level remained Orange (second highest) throughout the reporting period, except on 24 September, when it was briefly raised to Red due to strong explosions at 1238 that generated a large ash plume (207 x 250 km) that rose 11-11.5 km (figure 38); the Alert Level was lowered back to Orange that same day as the explosive activity subsided.

Figure 38. Photo of strong explosion on Sheveluch on 24 September 2014 that generated ash plumes which rose to at least 11 km in altitude. Photo by Y. Demyanchuk, Institute Volcanology and Seismology FEB RAS, KVERT.

In addition to the above activity, KVERT recorded a small pyroclastic flow on 7 January 2015 that descended the SE flank of the dome. Ashfall was reported in Klyuchi Village (50 km SW) on 12 January and in in Ust-Kamchatsk (85 km SE) on 4 March.

According to a news article (CNN), strong explosions on 28 February 2015 blew ash plumes across the Bering Sea into western Alaska and caused Alaska Airlines to cancel several flights. The article also indicated that an airlines spokesman mentioned that a similar cancellation had occurred in January.

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences, (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); 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/); Cable News Network (CNN), Turner Broadcasting System, Inc. (URL: http://www.cnn.com/).

Italy's Stromboli volcano, best known for lava fountain eruptions, has been essentially continuously active for at least the last 400 years. Confirmed historical observations of its eruptions go back 2,000 years. Frequent, mild explosive activity in 2013 was accompanied by lava flows and ash plumes (BGVN 40:11). Activity increased significantly during 2014 as reported by the Instituto Nazionale de Geofisica e Vulcanologia (INGV), Sezione de Catania, who monitors the gas geochemistry, deformation, and seismology, as well as the surficial activity. The Toulouse Volcanic Ash Advisory Center (VAAC) reports on ash plumes potentially affecting air travel. The activity at the summit consistently occurs from vents within two well defined north and south crater areas (figure 88) at the head of the Sciara del Fuoco, a large scarp that runs from the summit down the NW side of the island (see BGVN 36:09 for geologic map).

Figure 88. The crater terrace view of Stromboli from the SE (compare with figure 84, BGVN 40:11) showing active vents at the North and South Areas. Thermal image created 29 July 2014 by Luigi Lodato, INGV-OE, during an overflight by a Catania Coast Guard helicopter. Courtesy of INGV (Bollettino Stromboli 2014, 5 August).

A gradual increase of Strombolian activity from January through May 2014 was followed by small lava flows in June onto the Sciara del Fuoco. Several more lava flows in early July contributed to landslides that sent debris down the scarp into the ocean. In mid-July, four additional flows emerged and traveled down the scarp, with the flow on 19 July reaching the coastline. A strong surge in explosion frequency and intensity in early August caused 300-m-high fountains, followed by lava flows into the ocean for several days between 6 and 13 August. Minor ash emissions in early October sent plumes as high as 3 km altitude. Lava flows continued intermittently into October, but they no longer made it to the coast. Activity diminished significantly at the end of October 2014.

Activity during January-March 2014. After an explosive sequence on 25 December 2013 sent lapilli, bombs, and an ash plume above the summit craters, activity was quieter for several months. INGV reported that a medium-intensity explosive sequence of four events occurred from the S crater area on 4 January 2014. Lava fountaining with lapilli and bombs landing on the S part of the crater terrace and the S and E edges of the Sciara del Fuoco were reported, along with a minor landslide along the scarp. For the remainder of January, fountain explosion heights ranged from low (less than 80 m) to medium (less than 120 m) from the North (N) Area vents. Explosions of lapilli and bombs mixed with ash averaged 2-3 per hour. The South (S) Area vents sometimes exhibited medium-high-intensity (over 150 m) activity with discontinuous spattering, averaging 3-7 explosions per hour.

Only vent N1 in the North Area was active in February 2014. It was characterized by low- to medium-intensity explosive activity, emitting lapilli and bombs mixed with ash at a rate of 2-3 explosions per hour. In the South Area, vents S1, S3, and S4 were active at weak levels with emissions of fine ash mixed with some coarse material, at a rate averaging less than 6 explosions per hour.

Typical Strombolian activity during March included low- to medium-intensity explosive activity from both vent areas. A sequence of three explosions on 7 March from the South Vents led to the fallout of bombs on the upper side of the Sciara del Fuoco. At vent S1 vigorous activity on 14 March produced the rapid accumulation of lava fragments around the vent that flowed downward inside the terrace crater before subsiding. On 17 March small explosions at vent S3 briefly formed a new nearby vent with a persistent thermal anomaly. An increase in SO2 flux was observed in mid-March by INGV. The average frequency of explosions increased in the last week of March to 10-13 per hour, and the seismic amplitudes were also slightly higher in the second half of the month.

Activity during April-June 2014. Lapilli and bombs mixed with fine ash were typical from all vents during April 2014. The South Area had greater activity, with 3 or 4 vents active during the month, although the activity level was generally low- to medium-intensity in both areas. Frequency of events was generally average, ranging from 9 to 15 per hour. Activity in May 2014 was much the same as April in the N Area until the very end of the month when vent N2 began low-intensity explosive activity. All four vents in the S Area were active throughout May. Two intervals of high intensity spattering were reported on 13 and 19 May from the S Area vents. Explosion rates increased slightly during the month to averages of 11 to 18 per hour.

Activity continued to increase in both vent areas during June 2014. Explosions increased to a rate of more than 20 per hour several times during the month, accompanied by longer periods of spattering. Seismic tremor amplitudes also increased beginning at the end of May. Two periods of vigorous spattering led to lava flows. On 17 June, 70 minutes of vigorous spattering from vent S1 fed a lava overflow within the crater that flowed NE for a few tens of meters before cooling. On the morning of 22 June, vent N2 showed a marked increase in both frequency and intensity of activity. It was characterized by vigorous spattering and discrete bursts of high-intensity (over 200 m high) lava jets. The lava flowed from a crack at the edge of the vent and spread to the upper part of the Sciara del Fuoco. It flowed down the scarp for a few hundred meters before stopping early on 23 June. The South Area vents also had explosions over 200 m high beginning on 23 June. A lava flow emerged from vent S1 on 27 June; on 29 June, vent N2 produced two lava flows, the first remained within the crater, and the second, starting in the afternoon, continued flowing into 30 June, reaching the upper Sciara del Fuoco before stopping.

The first anomalies from the MODVOLC thermal alert system using MODIS satellite thermal data in 2014 appeared in early June and increased during the lava flow emissions that occurred at the end of the month.

Activity during July-October 2014. Three lava flows emerged from Vent N2 on 1, 4, and 7 July 2014. The first flowed E for two hours over the 29 June flow within the crater, and was followed later in the day by a second flow that moved towards the Sciara del Fuoco as did the flows on 4 and 7 July. Modest slumping of material around the western portion of the small pyroclastic cone that formed around Vent N2 led to a collapse and landslide that spread rapidly down the Sciara del Fuoco on 7 July. This led to a lava overflow on the upper part of the scarp for several hours during 7 July. Additional lava flows from Vent N2 occurred on 9 and 10 July as large blocks rolling down the scarp coalesced into a lava flow that continued until the evening of 10 July. Small landslides were triggered on the steep flanks of the scarp, and fine debris was carried downslope, almost to the coastline (figure 89).

Figure 89. An INGV thermal infrared camera located at 400 m elevation recorded effusive activity on 9 and 10 July 2014 at Stromboli. a) July 10, b) July 9, c) the arrows indicate small landslide events on the Sciara del Fuoco observed from the sea and also d) from an elevation of 190 m near the Observatory, during an inspection carried out by INGV-OE personnel on 14 July. Courtesy of INGV (Bollettino Stromboli 2014, 15 July).

Four lava flows emerged from vent N2 on 15, 16, 17, and 19 July, while activity at vent N1 continued as low- to high-intensity (up to 200 m high) explosions with lapilli and bomb ejections. The new flows were emplaced just north of the earlier flows. The flow on 19 July made it to the shoreline. Meanwhile, constant spattering and low-intensity explosions continued in the South area at all four vents. The locus of activity shifted during 21 and 22 July from the North Area to the South Area.

During 3 and 4 August, there was a strong surge in explosion frequency to averages of over 30 per hour with peaks of around 100 per hour. This resulted in high-intensity explosions (to over 300 m in height above the vents) from both the North and South Areas. A new lava overflow from the crater terrace began in the early afternoon of 6 August, following the same path down the center of the Sciara del Fuoco as other recent flows. Landslides of hot material quickly reached the coastline, raising large plumes of steam. Pulsating flows of lava later reached the coast and continued flowing into the early hours of 7 August. A new lava overflow from the N Area vents in the early morning of 7 August quickly formed a broad lava field at 600 m elevation and flowed onto the Sciara del Fuoco. Several arms of the lava flowed toward the coast and entered the sea (figure 90).

Figure 90. Three lava flows entering the sea at Stromboli, while two others, in the foreground, are about to reach the coastline. Taken from the SCT camera at 06:23 GMT on 7 August 2014. Courtesy of INGV (Stromboli Update, 7 August 2014, 0745 GMT).

Lava emissions continued from the N Area vents, reaching the coastline intermittently for several days, fanning out and covering large areas of the scarp, and generating steam jets and explosions with blocks of lava sent tens of meters high as the lava entered the ocean (figure 91). During this time, explosive activity decreased noticeably at the vents, while strong degassing continued. The lava continued to flow along the eastern edge of the Sciara del Fuoco with new flows covering earlier cooling flows as they traveled down the scarp to the coastline until 13 August. Lava effusion continued until mid-October but flows gradually retreated up the scarp, no longer reaching the sea.

Figure 91. Lava flows entering the sea at Stromboli during effusive activity on 10 August 2014. Courtesy of INGV (Stromboli Update, 10 August 2014, 1400 GMT).

Sporadic ash emissions in early October 2014 led to several reports from the Toulouse VAAC. Ash was reported in the vicinity of Stromboli at a low levels on 30 September, but it was not identifiable on satellite data. It was reported below 1.8 km altitude on 8 October, below 2.4 km on 9 October and below 3 km on 11 October.

A few intermittent MODVOLC thermal anomalies were recorded in July and then substantial anomalies appeared in August, with multiple-per-day continuously during 7-29 August. Almost daily multi-pixel anomalies continued in September and October, but ended abruptly on 28 October. Only one more anomaly was recorded on 8 November 2014. No additional reports on Stromboli were issued by INGV after the 16 October 2014 update.

Geologic Background. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Information Contacts: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/en/); Toulouse Volcanic Ash Advisory Center (VAAC), Météo-France, 42 Avenue Gaspard Coriolis, F-31057 Toulouse cedex, France (URL: http://www.meteo.fr/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: http://modis.higp.hawaii.edu/).

Continuous tremor, intervals with several explosions per day, and plumes rising to 5.5 km altitude were observed at Suwanosejima between 1 April 2013 and 14 December 2014 (BGVN 39:11). The data for this report, covering 5 January-11 September 2015, was gathered primarily from two key sources: the Tokyo Volcanic Ash Advisory Center (VAAC) and the Japan Meteorological Agency (JMA). Throughout the entire reporting period, no MODVOLC thermal anomalies were recorded, although the hazard status remained at Alert Level 2 (Do not approach the crater), on an increasing scale of 1-5. The Otake (also O-take) crater (figure 1) was the site of much of the activity during 2015.

Figure 19. Simplified map of the geology of Suwanosejima. The active crater, O-take (Oc), appears in the center of the small, sparsely populated island. Courtesy of Taketo Shimano.

In its Monthly Volcanic Activity Report for January 2015, JMA noted four explosive eruptions at the Otake crater, in addition to other occasional non-explosive eruptions. Grayish plumes accompanying the eruption rose as high as 1 km above the crater rim. On 25 January a field survey revealed a pit in the southeastern portion of the Otake crater which had formed since the previous survey on 8 November 2012.

Plumes in 2015 were reported by the VAAC in the months of January, February, April, July, August, and September. JMA served as the primary source for all of these VAAC notices; any additional sources are noted. The Tokyo VAAC reported that on 5 January ash plumes rose to altitudes of 1.5-1.8 km and drifted NE and SE, and were also observed by pilots. The VAAC also reported an explosion on 25 January, the same day as the field survey.

The Tokyo VAAC reported that during 11-12 and 14-15 February ash plumes rose to altitudes of 1.8-2.1 km and drifted E. JMA's monthly report for February 2015 indicated that twelve explosions occurred at Otake crater, in addition to occasional, non-explosive events. Grayish plumes accompanying the explosions rose as high as 1,500 m above the crater rim. According to the Suwanosejima branch of the Toshima Village administration, ash fall was observed at Kiriishi port (located ~3.5 km S. of Otake) on 26 February.

A very small eruption at the Otake crater on 5 March 2015 was noted by JMA. An event on 13 April reported by the Tokyo VAAC generated a plume that rose to an altitude of 2.1 km and drifted N. Explosions during 24-25 April generated plumes that rose to altitudes of 1.8-2.1 km and drifted N and SE.

JMA reported a continued high activity level at the Otake crater with very small eruptions recorded on 5 and 17 May 2015. No explosions were observed at the Otake crater in June. The Tokyo VAAC reported that ash plumes from small eruptions at Otake on 30-31 July rose to altitudes of 2.1-3 km and drifted E, SW, and W, as reported by pilots and seen in satellite data. Grayish plumes accompanying the eruption rose as high as 1,300 m above the crater rim. According to the Suwanosejima branch of the Toshima Village administration, ashfall was observed in a village ~4 km SSW of Otake on 31 July.

JMA's August 2015 report described small, occasional, non-explosive events at the Otake crater, with accompanying grayish plumes rising as high as 1.2 km above the crater rim. Volcanic "glow" was observed at the Otake crater occasionally at night with a high-sensitivity camera. According to the Toshima Village administration, ashfall 4 km SSW of Otake was again present on 1, 2, and 9 August. The Tokyo VAAC reported that ash plumes identified in satellite images rose to an altitude of 4 km on 2 August, and to 1.8 km on 21 August that drifted SE.

In the September 2015 report, JMA noted that volcanic activity had remained at high levels, with 89 explosions recorded at the Otake crater; 69 of those were on 24 September, the first time more than 50 explosions a day had been observed since 30 December 2013. Plumes accompanying the events rose as high as 1,500 m above the crater rim. Crater incandescence was observed at night with a thermal camera. According to the Toshima Village administration, ashfall was once again observed in a village 4 km SSW on 7 September. The Tokyo VAAC reported that on 13 September ash plumes rose to an altitude of 1.8 km and drifted SE. JMA noted that parts of local structures shook in association with explosions that occurred on 24 September. Explosions and rumbling were heard on the island.

Geologic Background. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

Small explosions have been recorded at Nicaragua's Telica volcano regularly since early in the 20th century. The last major eruptive episode began with a series of small explosions in March 2011 and culminated in greatly increased seismicity and several larger explosions during May that deposited ashfall in communities within 8 km of the volcano, and caused a small number of evacuations. Ash-bearing explosive activity died down by mid-June 2011, although steady degassing with gas-and-steam plumes continued. A small ash-and-gas explosion was reported on 25 September 2013.

On 7 May 2015 a new series of larger ash-and-gas explosions began. Nicaragua's Instituto Nicaragüense de Estudios Territoriales (INETER) provides monthly reports on seismic activity and monitoring of thermal and geochemical data as well as daily informational bulletins of volcanic activity; aviation advisories are also provided by the Washington Volcanic Ash Advisory Center (VAAC). Activity from June 2014 through August of 2016 is covered in this report.

A decrease in seismicity and increase in temperature within the summit crater at Telica in April 2015 preceded an ash-and-gas explosion on 7 May 2015 after several years of relative quiet. This was followed by a series of over 100 ash-bearing explosions in the following three weeks, the last on 28 May. Degassing from fumaroles continued without ash during June and the crater had cooled significantly by August. A new series of ash-and-gas explosion between 23 and 26 September 2015 sent ashfall to nearby communities and a few large volcanic bombs several hundred meters from the crater. The next series of explosions between 22 and 29 November sent ashfall to over 70 communities within 20 km of Telica. Incandescence was observed in a crack in the floor of the summit crater in December, but lava wasn't observed in the vent until 25 February 2016 after a sequence of gas explosions that lasted until 1 March. The lava and incandescence were observed until early May when explosions on 7-8 May 2016 were observed from a new vent in the N part of the crater. No further ash emissions were observed, and seismicity dropped significantly and remained quiet through August 2016.

Activity between June 2014 and May 2015. Remote temperature measurements of the summit crater floor at Telica showed a steady decline between May and July 2014 from an average of 417°C to 350°C, continuing a decline from values measured in 2013 that had been as much as 100°C hotter. During this time, few noises were heard and little incandescence from the crater was observed. There were no further reports until February 2015 when fresh landslides along the SE inner wall were observed blocking the vent; on a 25 February summit crater visit there was no noise, and few emissions from fumaroles were observed. Temperatures at the fumaroles on the SE, S and SW walls of the crater were around 150°C, and the floor of the crater was measured at 123°C with the Testo IR 820 thermometer. Gas emissions were more variable in March 2015, but again there was no noise or incandescence observed. The numbers of daily seismic events in March 2015, 3982, were generally within normal levels, ranging from a few to a few hundred per day, depending on type of seismicity.

The temperature at the floor of the crater in April 2015 had risen significantly to 412°C. The seismicity was also changed, with fewer total events (1,973). There was a noticeable drop in the number of events in the second half of April. As reported by INETER seismologist Virginia Tenorio, this decrease in number of events, accompanied by a narrowing of the frequency range to between 3 and 11 Hz, from a normally larger range of 3 to 30 Hz, also occurred prior to the last significant eruption in 2011.

Activity during May-August 2015. On 7 May 2015 at 1609 and 1615, INETER reported that Telica broke its "relative calm" since 26 September 2013 with two gas and ash explosions which rose about 200 m above the rim of the crater. This was the beginning of an eruptive period that included 902 seismically-detected explosions between 7 and 28 May, of which 104 were accompanied by volcanic ash (figure 35). Some also involved ejection of large incandescent lava blocks. Towns within 40 km in a generally W direction were affected by ashfall from these explosions.

Figure 35. Number of explosions per day at Telica during 7-31 May 2015. Top: Total explosions. Bottom: Explosions with ash. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

An explosion on 12 May ejected rocks 400 m high to the W. Minor ashfall was reported during May in El Realejo (35 km WSW), Corinto (40 km WSW), Posoltega (16 km SW), Guanacastal (20 km WSW), Quezalguaque (12 km SW), Chinandega (30 km W), El Viejo (35 km WNW), and Chichigalpa (20 km WSW). On 20 and 21 May, a series of explosions ejected one-m-diameter blocks up to 500 m from the crater. Many ash plumes were photographed by the INETER web camera located at the TELN seismic station on the E flank; others by INETER scientists at the volcano (figures 36-40).

Figure 36. Explosion at Telica on 8 May 2015 at 1002 local time. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

Figure 37. Explosion at Telica photographed by the web camera at seismic station TELN on the E flank, 17 May 2015, 0957 local time. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

Figure 38. Incandescent ejecta from Telica at 1906 local time on 20 May 2015. Photographed by the web camera at the TELN seismic station on the E flank. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

Figure 39. Block ejected from Telica on 23 May 2015. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

Figure 40. Ash explosion at Telica, 1000 local time 27 May 2015. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

On only two dates during May did these explosions initiate reports from the Washington VAAC; they reported ash emissions on 11 May rising to 1.8 km and drifting W, and twice on 26 May. The first plume on 26 May extended 75 km W below 3 km altitude, and a second drifted 117 km WNW of the summit at 4.3 km before dissipating.

Visits to the crater on 8 and 14 May revealed a new vent at the base of the S wall of the crater that formed during the 7 May explosion (figure 41). There was a substantial increase in temperature inside the crater from 150°C to 377°C between these dates. The first explosion with incandescent material was observed on 10 May. SO2 measurements of 1,000-1,500 tons per day (t/d) were taken during an explosion on 26 May (figure 42), and values were significantly higher than previous levels of around 300 t/d.

Figure 41. New vent on the S wall of the summit crater at Telica formed during the 7 May explosion. Photo taken 8 May 2015. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

Figure 42. Ash explosion at Telica, 26 May 2015 during which SO2 measurements of 1,000-1,500 tons per day (t/d) were measured. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Mayo 2015).

Seismicity in May was high, with 18,858 recorded events. The high number of volcano-tectonic events (VT) during the month (605) was associated with the ruptures that triggered explosions; they have a characteristic frequency of 4.5 to 10.0 Hz. Most of the VT events were located between 6 and 10 km below the surface. The majority of the total seismic events in May were related to degassing and gas explosions (18,087). Screw-type "tornillo" earthquakes are usually rare at Telica, but about 46 of them were observed in May.

The volcano remained relatively calm during June, with the number of daily seismic events typically at 10 or lower, far fewer than May. Even fewer seismic events (71) were recorded in July along with gas emissions that were variable but generally light. The most degassing came from fumaroles located on the inner walls of the crater where the temperature was measured at 298°C. On a 25 August visit to the crater, INETER technicians noted that the points where incandescence had been observed prior to May had disappeared, and temperatures at the fumaroles on the SW and NE walls ranged from 50°C to 160°C.

Activity during September 2015-August 2016. A new gas-and-ash explosion at 0800 on 23 September 2015 sent ash to the NW, W, and SW. The plume rose to 400 m above the crater. Other smaller explosions with small quantities of ash continued that day and the next. Ashfall was reported in the community of Guanacastal (20 km WSW). Additional medium-intensity explosions on 26 September ejected gas, ash, and rock fragments up to 500 m from the crater. Ash plumes reached 1,000 m above the crater and drifted W and NW. The Washington VAAC reported these emissions at 4.3 km altitude, drifting N and W about 45 km (figure 43). This second series of explosions opened a new vent on the N side of the crater floor, and gas emissions continued from both vents. Seismic events in September numbered 775.

Figure 43. Ash explosion at Telica at 0845 (local time) on 26 September 2015. Location uncertain but likely in the vicinity of Leon, about 20 km S of the volcano. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Septiembre 2015).

During October, no ash explosions were recorded, although 2,921 total seismic events were reported. On 22 November 2015 a new series of explosions began, lasting for eight days. That day, the Washington VAAC reported an ash plume to 2.4 km that drifted about 185 km W. According to a news article published by el19, two explosions, at 0847 and 0848, generated ash plumes that rose 2 km and ejected tephra at least 900 m away (figure 44). Residents in Agua Fría (900 m away) noted it was the first time lapilli and blocks had reached their community. La Prensa reported that ash fell in at least 70 communities in the municipalities of Quezalguaque (13 km SW), Posoltega (16 km WSW), Chichigalpa (20 km WSW), and Chinandega (30 km W).

Figure 44. Explosion at Telica at 0845 (local time) on 22 November 2015. Taken from the web camera at seismic station TELN on the E flank. Courtesy of el19 digital.com (https://www.el19digital.com/articulos/ver/titulo:35988-volcan-telica-registra-fuerte-explosion ).

INETER reported that during 25-27 November numerous small explosions were recorded, most of which generated volcanic ash, with the highest plume reaching 800 m above the crater. Satellite imagery reported from the Washington VAAC showed a faint plume extending about 16 km WSW at 1.2 km altitude on 26 November. Occasional emissions continued until 29 November with several VAAC reports indicating plumes at 1.5 km altitude visible in satellite imagery drifting up to 45 km W and SW.

While no explosions were reported during December 2015, the INETER volcano observer (René Dávila) noted that incandescence was observed in a N-S trending fracture on the crater floor during a visit to the summit. Seismicity was low in December, with a total of 1,342 events recorded, although there was an increase in micro-seismicity during the second half of the month. Even fewer seismic events were reported in January 2016 (171 events), along with few gas emissions that seldom rose above the crater rim.

On 13 February 2016 emissions were observed in visible satellite imagery by the Washington VAAC moving WSW from the summit that likely contained ash. This was preceded by a burst of seismic activity reported by INETER. They noted intermittent high micro-seismicity between 16 February and 1 March. Incandescence from the vent on the crater floor increased during February; lava on the crater floor was first observed by INETER on 25 February. Small gas explosions were observed inside the crater during 24- 26 February followed by five gas-and-ash explosions recorded during 29 February-1 March which generated plumes that rose 300 m above the crater and drifted W and SW. Gas-and-ash emissions lasted for 14 minutes during the strongest of these events.

A visit to the crater on 15 March 2016 by INETER scientists provided additional evidence of incandescence within the crater and a temperature reading of 485° C (figure 45).

Figure 45. Night view of the incandescence in the crater of Telica taken on 15 March 2016. Courtesy INETER (Boletin mensual Sismos Y Volcanes de Nicaragua, Marzo 2016).

From late March through early May, INETER reported incandescence and lava inside a vent on the crater floor, and micro-seismicity remained high even though gas emissions and RSAM values were low. The last report of incandescence from the vent on the crater floor was during the second week of May. RSAM values had dropped to 80 units by 14 May.

Based on information from INETER, SINAPRED reported that 30 explosions occurred during 7-8 May 2016, producing gas-and-ash plumes that rose 600 m and drifted S and SW. The explosions originated from a new vent in the N part of the crater. Seismic RSAM amplitudes spiked to several hundred units between 8 and 12 June, but there were no reports of ash emissions after 8 May from either the Washington VAAC or INETER.

In late July 2016 scientists visited the Las Quemadas, Aguas Frías, (Hot Spring) located 1.7 km north-east of Telica to study temperature and chemistry of the geothermal waters. Seismicity and RSAM values remained low through August 2016 with no further reports of ash emissions or lava in the crater.

Geologic Background. Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately E, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://webserver2.ineter.gob.ni/vol/dep-vol.html); 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: http://www.ospo.noaa.gov/Products/atmosphere/vaac/ , archive at: http://www.ssd.noaa.gov/VAAC/archive.html); Sistema Nacional para la Prevencion, Mitigacion y Atencion de Desastres, (SINAPRED), Edificio SINAPRED, Rotonda Comandante Hugo Chávez 50 metros al Norte, frente a la Avenida Bolívar, Managua, Nicaragua (URL: http://www.sinapred.gob.ni/); El19digital, https://www.el19digital.com/articulos/ver/titulo:35988-volcan-telica-registra-fuerte-explosion; La Prensa, http://www.laprensa.com.ni/2015/11/22/departamentales/1940877-volcan-telica-lanza-piedras-cenizas-dos-mil-metros-altura .