Bulletin of the Global Volcanism Network

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

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

 Bulletin of the Global Volcanism Network - Volume 41, Number 07 (July 2016)


Managing Editor: Edward Venzke

Bagana (Papua New Guinea)

Regular ash plumes and intermittent thermal anomalies during January-June 2016

Lascar (Chile)

Ash plume on 30 October 2015 rises 2,500 m high; variable seismicity and persistent thermal anomaly afterwards

San Cristobal (Nicaragua)

Ash explosion on 22 April 2016



Bagana (Papua New Guinea) — July 2016 Citation iconCite this Report

Bagana

Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)


Regular ash plumes and intermittent thermal anomalies during January-June 2016

Volcanic activity at Bagana for the first half of 2016 was characterized by intermittent ash emissions and thermal anomalies similar to 2015. Evidence comes from the Darwin VAAC (Volcanic Ash Advisory Center) and MODIS infrared satellite data as processed by both MODVOLC (Moderate Resolution Imaging Spectroradiometer) and MIROVA (Middle InfraRed Observation of Volcanic Activity) , and OMI (Ozone Monitoring Instrument) SO2 data. No ground observations were reported during this time. The intermittent yet continuous nature of the eruption is best seen in the MIROVA data (figure 26).

Figure (see Caption) Figure 26. Infrared MODIS data processed by MIROVA showing the Log Radiative Power, characterizing the strength of the thermal anomaly, for Bagana from July 2015 through June 2016. The Volcanic Radiative Power (VRP) is a measurement of the heat radiated by the volcanic activity at the time of a satellite acquisition. It is calculated in watts (W) and represents a combined measurement of the area of the volcanic emitter and its "effective radiating temperature" (higher than 600° K, or 327°C). This "excess" radiance is linearly related to the radiative power. Note continued pulses of moderate radiative power between January and June 2016, with episodes in early March and late April approaching 108 VRP. Image courtesy MIROVA.

MODVOLC only recorded single-pixel anomalies twice in January (7 and 23) near the summit on the north side. MIROVA (figure 26) also shows anomalies, likely on the same days in January and several other days in January and February, at levels consistently below 107 Watts VRP, indicating that Volcanic Radiative Power (VRP) was low but at detectable in January and February.

Darwin VAAC issued reports on ash plumes three times in March (3-4, 11, and 24). During 3-4 and 11 March, the plumes rose to 2.1 km and drifted 40-110 km N, NE and SE. A higher plume on 24 March rose to 3.6 km and was observed and modeled drifting 45-55 km NE and ENE. Additionally, the 11 March event was captured by MODVOLC as three pixels N and W of the summit. A small SO2 anomaly on 15 March was observed by the OMI instrument (figure 27); it quickly dissipated to the ESE within 48 hours. Another MODVOLC anomaly on 18 March of two pixels appeared a short distance NNE of the summit.

Figure (see Caption) Figure 27. SO2 anomaly from OMI over Bagana on 15 March 2016. It appeared very diffuse on the 16 and 17 March images, and drifted ESE. Bagana is the triangle underneath the SO2 anomaly. Image courtesy of NASA Goddard Space Flight Center.

MODVOLC thermal anomalies of one or two pixels appeared three times in April (14, 17, and 21), all without corresponding Darwin VAAC reports. They were located slightly N, NE, and NW of the summit. Darwin VAAC reported two separate plume events later in April and early May. During 23-24 April a plume was observed at 2.1-3 km altitude drifting 25-35 km S and SW. An extended report of plumes from 26 April to 5 May by Darwin VAAC likely correlate with the MIROVA VRP spikes during that period (figure 26). These plumes rose to 2.1 km and drifted 45-100 km SW, W, and NW. The plumes were "clearly observed" by Darwin VAAC during this interval in visible satellite imagery on 26 and 28 April and 3 and 4 May.

Six more series of Darwin VAAC reports of ash plumes between 7 May and 16 June indicate continued activity. All plume heights were recorded as 2.1 km and drift distances were up to 140 km in various directions. Four of the report series only lasted up to 36 hours (7-8 May, 22 May, 2 June, and 16 June), but two of the report series covered longer periods of plume activity (25-29 May, 8-12 June).

Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

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/); MIROVA, 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://hotspot.higp.hawaii.edu/); OMI (Ozone Monitoring Instrument), Global Sulfur Dioxide Monitoring, Atmospheric Chemistry & Dynamics, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://so2.gsfc.nasa.gov/)


Lascar (Chile) — July 2016 Citation iconCite this Report

Lascar

Chile

23.37°S, 67.73°W; summit elev. 5592 m

All times are local (unless otherwise noted)


Ash plume on 30 October 2015 rises 2,500 m high; variable seismicity and persistent thermal anomaly afterwards

Lascar experienced one significant volcanic event between January 2014 and June 2016, a 2,500-m-high ash plume on 30 October 2015, according to reports issued by Chile's SERNAGEOMIN-OVDAS (Servicio Nacional de Geología y Minería, Observatorio Volcanológico de los Andes del Sur). Seismicity, deformation, SO2 emissions, and thermal anomalies were all monitored by the agency during this time. A thermal anomaly persisted following the 30 October explosion through at least 16 June 2016.

The volcano had a maximum of eight volcano-tectonic (VT) seismic events per month (in September 2014 and October 2015) recorded between January 2014 and June 2016, and usually only 2-4 events. The local magnitude ranged from 0.5 to 2.5. The distance from the crater was also variable, ranging from inside the crater (June and July 2014), to as far as 15 km NE (September 2014). Seismic events were located in many different directions from the central crater. The depth of the events ranged from 0.6 km (March 2014) to 9 km (February 2016).

The long-period (LP) seismic events showed a more consistent trend. From March through August 2014, there were fewer than 6 events recorded each month. In September, the number-of-events increased to 13, and then beginning in November 2014, over 100 LP events were recorded monthly through July 2015. The largest number was in May 2015 with 209 events. Numbers decreased to 54 in October 2015, and then dropped back into the single digits in November 2015 (after the ash event on 30 October). Eight or fewer LP events occurred monthly during the first half of 2016. All LP events had local magnitudes (ML) less than 1.3, most had values less than 1.0.

Outgassing was regularly observed, with the highest monthly plume heights reported ranging from 600 to 2,000 m between March 2014 and September 2015. At 0932 local time on 30 October 2015, the webcam captured an ash emission rising 2,500 m above the summit and drifting NE over the volcanic complex. Based on this activity, the Alert Level was raised to Yellow (the second on a four-color scale). The Chilean Oficina Nacional de Emergencia Ministerio del Interior (ONEMI) declared a Yellow Alert for the municipality of San Pedro de Atacama, located 70 km NW of the volcano. The Buenos Aires VAAC also identified a short plume near the summit in satellite imagery which dispersed quickly. The Alert Level was lowered back to Green on 16 November 2015. Water-vapor rich emissions to 2,000 m were reported from November 2015 through June 2016, with no additional ash emissions observed.

Incandescence at the summit was observed in March and April 2014, and November 2015. The only SO2 anomaly occurred on 30 October 2015 during the ash-plume event. It was recorded by the OMI instrument via satellite at 49 kilotons. Otherwise SO2 levels at the volcano were within the normal range, with minor fluctuations.

Small thermal anomalies were intermittent prior to late October 2015, at which time the MIROVA data shows infrared (IR) signatures at the summit consistently, continuing through at least 16 June 2016 (figure 49), with the intensity and frequency slowly decreasing. No MODVOLC anomalies were recorded during this period.

Figure (see Caption) Figure 49. Thermal anomaly (Log Radiative Power) data for Lascar volcano showing abrupt appearance of a low thermal anomaly on 30 October 2015 during a 2,500-m-high, ash-plume emission. The anomalies continue, decreasing slightly in both intensity and frequency. Note that the white line indicates the day (17 June 2016) this graph was last updated. Courtesy of MIROVA.

Geologic Background. Láscar is the most active volcano of the northern Chilean Andes. The andesitic-to-dacitic stratovolcano contains six overlapping summit craters. Prominent lava flows descend its NW flanks. An older, higher stratovolcano 5 km E, Volcán Aguas Calientes, displays a well-developed summit crater and a probable Holocene lava flow near its summit (de Silva and Francis, 1991). Láscar consists of two major edifices; activity began at the eastern volcano and then shifted to the western cone. The largest eruption took place about 26,500 years ago, and following the eruption of the Tumbres scoria flow about 9000 years ago, activity shifted back to the eastern edifice, where three overlapping craters were formed. Frequent small-to-moderate explosive eruptions have been recorded since the mid-19th century, along with periodic larger eruptions that produced ashfall hundreds of kilometers away. The largest historical eruption took place in 1993, producing pyroclastic flows to 8.5 km NW of the summit and ashfall in Buenos Aires.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/volcanes.php); Observatorio Volcanológico de los Andes del Sur (OVDAS), Temuco, (URL: http://www.sernageomin.cl/volcan-observatorio.php); Oficina Nacional de Emergencia Ministerio del Interior (ONEMI), (URL: http://www.onemi.cl/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.meteofa.mil.ar/vaac/vaac.htm); MIROVA, 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/)


San Cristobal (Nicaragua) — July 2016 Citation iconCite this Report

San Cristobal

Nicaragua

12.702°N, 87.004°W; summit elev. 1745 m

All times are local (unless otherwise noted)


Ash explosion on 22 April 2016

After ash explosions on 6 and 12 June 2015 (BGVN 40:09), San Cristóbal remained quiet for the rest of the year. Monthly reports from INETER (Instituto Nicaragüense de Estudios Territoriales) described degassing from the fumarolic vents which had consistent temperature variations in the 60° to 80°C range as regularly measured since December 2014. Landslides on the S and SE flanks of the inner crater were observed in November 2015. The number of seismic events continued a downward trend from 510 in September 2015 to 147 events in December. Over 90% of the events were related to degassing, with the remainder being VT (volcano-tectonic), LP (long-period), or tremor events. RSAM values generally remained in the background range of 25-30 units.

Seismicity remained low in January 2016 with only 130 seismic events recorded and RSAM values between 30 and 40 units. Observations of the gas plume indicated that it generally drifted WSW or NW, rising only a small distance above the summit.

At 1020 on 22 April 2016 both INETER and SINAPRED (Sistema Nacional para la Prevencion, Mitigacion y Atencion de Desastres) reported an explosion which sent an ash-and-gas plume 2 km above the crater that drifted SW. The seismic network recorded 10 additional explosions by 1200. Ashfall was reported in local areas, including Las Brisas (10 km S), San José (8 km SSE), Santa Narcisa, Pellizco Central (12 km SSE), Los Ébanos, Los Lirios (18 km WSW), Santa Cruz (35 km SE), Las Grietas (14 km E), El Liberal, and San Lucas (13 km E). The INETER report noted that this event was larger than the explosive activity in June 2015.

Continued temperature observations of the fumaroles from the SE part of the crater in June 2016 showed little variation from average values over the last two years (figure 32).

Figure (see Caption) Figure 32. Fluctuations of fumarole temperatures from the SE part of the crater at San Cristobal from December 2014 through June 2016 show consistent variation and range of values. Courtesy of INETER (Monthly Report, June 2016).

INETER periodically measures SO2 emissions from San Cristobal. Measurements in June 2016 from two separate transects returned average values of 558 and 477 tons per day on 10 and 24 June, respectively. The transects covered regions 10-15 km from the volcano on the west side. The values were very similar to those collected in October 2015.

Geologic Background. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1745-m-high youngest cone, named San Cristóbal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km W of San Cristóbal; it and the eroded Moyotepe volcano, 4 km NE of San Cristóbal, are of Pleistocene age. Volcán Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/geofisica/); 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/)

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 Atmospheric Effects


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

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 Special Announcements


Special announcements of various kinds and obituaries.

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 Additional Reports


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

Turkey


False Report of Sea of Marmara Eruption


Africa (northeastern) and Red Sea


False Report of Somalia Eruption


Africa (eastern)


False Report of Elgon Eruption


Kermadec Islands


Floating Pumice (Kermadec Islands)

1986 Submarine Explosion


Tonga Islands


Floating Pumice (Tonga)


Fiji Islands


Floating Pumice (Fiji)


New Britain


Likuranga


Andaman Islands


False Report of Andaman Islands Eruptions


Sangihe Islands


1968 Northern Celebes Earthquake

Kawio Barat


Mindanao


False Report of Mount Pinokis Eruption


Southeast Asia


Pumice Raft (South China Sea)

Land Subsidence near Ham Rong


Ryukyu Islands and Kyushu


Pumice Rafts (Ryukyu Islands)


Izu, Volcano, and Mariana Islands


Mikura Seamount

Acoustic Signals in 1996 from Unknown Source

Acoustic Signals in 1999-2000 from Unknown Source


Kuril Islands


Possible 1988 Eruption Plume


Mongolia


Har-Togoo


Aleutian Islands


Possible 1986 Eruption Plume


Mexico


False Report of New Volcano


Nicaragua


Apoyo


Colombia


La Lorenza Mud Volcano


Ecuador


Altar


Pacific Ocean (Chilean Islands)


False Report of Submarine Volcanism


Central Chile and Argentina


Estero de Parraguirre


West Indies


Mid-Cayman Spreading Center


Atlantic Ocean (northern)


Northern Reykjanes Ridge


Azores


Azores-Gibraltar Fracture Zone


Antarctica and South Sandwich Islands


Jun Jaegyu

East Scotia Ridge



 Special Announcements


Special Announcement Reports