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 42, Number 10 (October 2017)

Managing Editor: Edward Venzke

Dieng Volcanic Complex (Indonesia)

Three phreatic eruptions at Sileri Crater; deaths due to helicopter crash involved in evacuations

Heard (Australia)

Expedition visit in March-April 2016, intermittent eruptive activity through September 2017

Ubinas (Peru)

Intermittent ash explosions during September 2016-February 2017

Dieng Volcanic Complex (Indonesia) — October 2017 Citation iconCite this Report

Dieng Volcanic Complex


7.2°S, 109.879°E; summit elev. 2565 m

All times are local (unless otherwise noted)

Three phreatic eruptions at Sileri Crater; deaths due to helicopter crash involved in evacuations

Located on an elevated plateau in central Java NW of Yogyakarta (figure 4), multiple craters within the Dieng Volcanic Complex (figure 5) have been intermittently active over the past 200 years. Brief phreatic eruptions took place at Sibanteng crater on 15 January 2009 (BGVN 34:04) and at Sileri crater on 26 September later that year (BGVN 34:08). Increased unrest during March-April 2013 (BGVN 38:08) consisted of elevated volcanic gas emissions from Timbang Crater that resulted in an increase in the Alert Level to as high as 3 on 27 March, then back to Level 2 on 8 May. There was a precautionary evacuation of local villages, but no eruption took place. Regular monitoring is done by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Centre for Volcanology and Geological Hazard Mitigation or CVGHM).

Figure (see Caption) Figure 4. Topographic terrain map of central Java showing the Dieng Volcanic Province to the NW of Gunung Sumbing and Gunung Sindoro volcanoes. The volcano indicated by a red symbol N of Yogyakarta is Merapi. Courtesy of Peakery.
Figure (see Caption) Figure 5. Topographic terrain map of the Dieng Volcanic Province on the Dieng plateau of central Java. The notable cone at bottom center is Bisma; the crater with a lake at center is Merdada, adjoining Kawah Sikidang to the SE. The frequently active Sileri area is immediately W of the more noticeable Pagerkandang crater N of Merdada. Courtesy of Peakery.

The alert status remained at Level 2 for about 15 months following the hazardous gas emissions in 2013. On 11 August 2014 the PVMBG noted that, due to decreased activity and no observable flow of gas in high concentrations from the crater, the Alert Level was lowered to 1 (on a scale of 1-4). No further activity was reported until late April 2017.

A phreatic event from Sileri Crater at 1303 on 30 April 2017 ejected material 10 m high and 1 m past the crater edge, forming a 1-2 mm thick deposit. Another emission at 0941 on 24 May consisted of gas and black "smoke" that rose 20 m.

The Disaster Management Authority, Badan Nacional Penanggulangan Bencana (BNPB), reported that there had been another phreatic eruption from the Sileri Crater lake at 1154 on 2 July 2017, ejecting mud and material 150 m high, and 50 m to the N and S. The event injured 11 of 18 tourists that were near the crater. According to a news article a helicopter on the way to assist with evacuations after the event crashed, killing all eight people (four crewmen and four rescuers) on board. PVMBG scientists visited the next day and observed weak white emissions rising 60 m.

PVMBG reported that during 8 July-14 September 2017 measurements indicated an increase in water temperature at Sileri Crater lake from 90.7 to 93.5°C. Soil temperatures also increased, from 58.6 to 69.4°C. At Timbang Crater temperatures in the lake increased from 57.3 to 62.7°C, and in the soil they decreased from 18.6 to 17.2°C. The report noted that conditions at Timbang Crater were normal.

Temperature increases at Sileri, along with tremor detected during 13-14 September, prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4). PVMBG warned the public to stay at least 1 km away from the crater rim, and for residents living within that radius to evacuate. However, after 20 September tremor and water temperatures both declined. The Alert Level was lowered back to 1 on 2 October, with a warning to stay at least 100 m from the crater rim.

Geologic Background. The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century CE. The Dieng volcanic complex consists of two or more stratovolcanoes and more than 20 small craters and cones of Pleistocene-to-Holocene age over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of dissected to youthful cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but have not occurred in historical time, when activity has been restricted to minor phreatic eruptions. Toxic gas emissions are a hazard at several craters and have caused fatalities. The abundant thermal features and high heat flow make Dieng a major geothermal prospect.

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/); 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/); Peakery (URL: https://peakery.com/).

Heard (Australia) — October 2017 Citation iconCite this Report



53.106°S, 73.513°E; summit elev. 2745 m

All times are local (unless otherwise noted)

Expedition visit in March-April 2016, intermittent eruptive activity through September 2017

The remote island of Heard in the southern Indian Ocean is home to the Big Ben stratovolcano, which has had confirmed intermittent activity since 1910. The nearest continental landmass, Antarctica, lies over 1,000 km S. Visual confirmation of lava flows on Heard are rare; thermal anomalies detected by satellite-based instruments provide the most reliable information about eruptive activity. Thermal alerts reappeared in September 2012 after a four-year hiatus (BGVN 38:01), and have been intermittent since that time. Information comes primarily from MODVOLC and MIROVA thermal anomaly data, but Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) also provides reports from research expeditions. The independent March-April 2016 Cordell Expedition also provided recent ground-based observations mentioned in this report, which covers activity through September 2017.

Expeditions during January-April 2016. Scientists aboard the CSIRO Research Vessel Investigator observed an eruption of Big Ben on 31 January 2016. Vapor was seen emanating from the peak and lava flowed down the flank over a glacier (see figure 23, BGVN 41:08, and video link in Information Contacts). The research team, lead by the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS), was conducting a study of the link between active volcanoes on the seafloor and the mobilization of iron by hydrothermal systems which enriches and supports life in the Southern Ocean.

During a private expedition from 22 March to 11 April 2016, scientists and engineers from the 2016 Cordell Expedition documented changes to the island and its life since a prior visit in 1997, and tested radio operations. On 23 March the team was able to photograph the usually cloud-covered Mawson Peak, the summit of Big Ben (figure 24). Steam was visible above the flat upper surface, possibly a crater rim or fissure. They estimated a height of about 45 m of an edifice rising above the adjacent slope. The ground at the site of the team campsite, near Atlas Cove on the NW side of the island, was covered with lava flows (figure 25). While the expedition had to cancel a planned expedition to the summit, rocks collected from the shoreline confirmed the diversity of volcanic rocks on the island (figure 26).

Figure (see Caption) Figure 24. Mawson Peak is the summit of Big Ben volcano on Heard Island in the southern Indian Ocean. This photograph, taken on 23 March 2016 from Altas Cove on the NW side of the island by the 2016 Cordell Expedition, shows steam from a possible crater or vent area at the summit, and lava flows covered with a dusting of snow around the otherwise glacier-covered peak. Courtesy of Robert W. Schmieder, 2016 Cordell Expedition, used with permission.
Figure (see Caption) Figure 25. Lava flows cover the ground near the 2016 Cordell Expedition campsite at Atlas Cove on the NW side of Heard Island in March 2016. Courtesy of Robert W. Schmieder, 2016 Cordell Expedition, used with permission.
Figure (see Caption) Figure 26. Rock samples collected at Heard by the 2016 Cordell Expedition during 23 March-11 April 2016 attest to the volcanic activity of the island. Top: A conglomerate sampled from the east shore of Stephenson Lagoon with mostly volcanic rock fragments, including vesicular basalt (dark brown, lower center) and clasts of volcanic breccia containing fragments of lava (large clast on right side). Sample is about 25 cm long. Bottom: A variety of textures was typical in the volcanic rocks collected on the islands. Courtesy of Robert W. Schmieder, 2016 Cordell Expedition, used with permission.

At the southern end of Sydney Cove, near Magnet Point on the northern tip of Laurens Peninsula (the NW side of the island), the team identified a small islet, with dimensions of about 40 x 120 m and nearly vertical sides about 100 m high. Columnar jointing in the volcanic rocks is well exposed at the base and on the nearly flat upper surface (figure 27).

Figure (see Caption) Figure 27. Distinctive columnar jointing in the volcanic rocks is visible around the base and on the top of a small islet in Sydney Cove off the NW end of Heard Island in this image taken during the 23 March-11 April 2016 Cordell Expedition. Courtesy of Robert W. Schmieder, 2016 Cordell Expedition, used with permission.

Satellite thermal and visual data, 2012-2017. The most consistent source of information about eruptive activity at Heard comes from satellite instruments in the form of visual and thermal imagery, and thermal anomaly detection. From the time that renewed activity was detected in MODVOLC data in late September 2012 through September 2017, either the MODVOLC or MIROVA systems have consistently detected thermal signals, with only a few short breaks. A four-month span from mid-July to mid-November 2014, and a two-month gap during February and March 2015 are the only periods longer than a month when no thermal signal was reported. Continuous MIROVA information from late January 2016 through September 2017 shows intermittent but persistent thermal anomalies throughout the period (figure 28).

Figure (see Caption) Figure 28. A continuous MIROVA signal from 27 January 2016 through 6 October 2017 shows persistent low-level thermal activity through the period with intervals of increased activity during late January 2016, July-August 2016, late September-November 2016, early February 2017, and September 2017. Courtesy of MIROVA.

The moderate signal at the very end of January 2016 coincides with the CSIRO expedition observing the lava flows on the flank of Big Ben. Low-level MIROVA anomalies were recorded in April and early May 2016. Activity picked up during June, and strengthened through July and August 2016. Late September through November 2016 was a period with heightened activity as well. From December 2016 through August 2017, intermittent low-to-moderate intensity anomalies were recorded every month. Activity appeared to increase briefly during early February and September 2017. On 4 February 2017, Landsat 8 captured a rare clear view that showed fresh lava and debris flows emanating from the summit on top of the snow (figure 29). The longest flow is estimated to be 1,300 m long. False-color infrared imagery of the same image of Mawson Peak also reveals two vents separated by about 250 m (figure 30). Subsequent imagery on 20 and 27 February also detected thermal anomalies at the summit. The visual imagery of the lava flows on 4 February 2017 corresponds to the early February spike in MIROVA thermal anomaly data.

Figure (see Caption) Figure 29. Lava and debris flows radiate away from Mawson Peak on Heard Island in this Landsat 8 OLI image captured on 4 February 2017. MIROVA thermal anomaly data show a spike in activity at the same time. Courtesy of NASA and Bill Mitchell (CC-BY).
Figure (see Caption) Figure 30. False-color infrared imagery of Mawson Peak, Heard Island, 4 February 2017. Two vents are visible in red-yellow, separated by about 250 m. Data source: Landsat 8 OLI/TIRS bands 7-6-5. Image courtesy of Bill Mitchell (CC-BY), data from NASA/USGS.

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 volcano lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben volcano because of its extensive ice cover. The historically active Mawson Peak forms the island's 2745-m 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 in historical time at this isolated volcano, but observations are infrequent and additional activity may have occurred.

Information Contacts: Commonwealth Scientific and Industrial Research Organisation (CSIRO), URL: www.csiro.au.; CSIROscope, CSIRO Blog, Big Ben Erupts: Australia's active volcano cluster blows its lid, (URL: https://blog.csiro.au/big-ben-erupts/); Robert W. Schmieder, 2016 Cordell Expedition, 4295 Walnut Blvd., Walnut Creek, CA 94596, Post Expedition report to the Australian Antarctic Division (AAD), (URLs: www.cordell.org, www.heardisland.org); 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/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Bill Mitchell, The Inquisitive Rockhopper, Big Ben eruption update 2017-02-27, (URL: https://inquisitiverockhopper.wordpress.com/2017/02/).

Ubinas (Peru) — October 2017 Citation iconCite this Report



16.355°S, 70.903°W; summit elev. 5672 m

All times are local (unless otherwise noted)

Intermittent ash explosions during September 2016-February 2017

Ubinas is an active stratovolcano in southern Peru about 70 km E of the city of Arequipa. Holocene lava flows cover its flanks, and the historical record since the mid-1500's contains evidence of minor explosive eruptions, debris avalanches, tephra deposits, phreatic outbursts, and pyroclastic flows and lahars. An eruptive episode that began with phreatic explosions on 1 September 2013 lasted through 27 February 2016, producing numerous small ash emissions, several large explosions with ash plumes that rose above 10 km altitude, large SO2 anomalies, evacuations, and several millimeters of ashfall in surrounding villages. Significant MIROVA thermal anomalies first appeared in mid-June 2015 and persisted through January 2016. A smaller eruptive episode described below began on 13 September 2016 and continued with intermittent explosive activity through 2 March 2017. Information is provided by the Instituto Geofísico del Perú, Observatoria Vulcanologico del Sur (IGP-OVS), the Observatorio Volcanológico del INGEMMET (Instituto Geológical Minero y Metalúrgico) (OVI-INGEMMET), and the Buenos Aires VAAC (Volcanic Ash Advisory Center).

After activity subsided at the end of February 2016, Ubinas remained quiet through August 2016, with only sporadic steam and gas emissions, and very low levels of seismicity. Seismicity increased again beginning on 9 September, and the first ash emission of a new episode was reported on 13 September 2016. An explosion on 3 October released a significant ash plume that rose 2 km above the 5,672-m-summit. Four additional explosions with minor ash emissions were reported in November, and one occurred on 6 December. Webcams captured images of sporadic low-density ash emissions throughout February 2017, with the last report of possible emissions on 2 March 2017. Emissions of steam and gas and seismicity decreased throughout April 2017, and IGP-OVS lowered the alert level to Green by the end of May. Ubinas remained quiet through September 2017.

Activity during April-December 2016. After the small ash emission of 27 February 2016, seismicity at Ubinas dropped to very low levels of a few events per day (BGVN 41:10, figure 40). Sporadic steam emissions with small quantities of bluish magmatic gases rose no more than a few hundred meters above the summit during March-August 2016; there were no reports of ash emissions. A small seismic swarm of about 100 earthquakes was recorded on 5 April. The first "tornillo" type earthquakes seen in several months appeared beginning on 4 June, indicating to IGP-OVS the beginning of a new eruptive cycle. The lagoon that had formed at the bottom of the summit crater due to rains earlier in the year began to disappear as the dry season approached (figure 41).

Figure (see Caption) Figure 41. A view down into the steep-sided summit crater at Ubinas shows remnants of a disappearing lake after the rainy season, during the second quarter of 2016. Photo by Melquiades Álvarez; courtesy of OVS (Reporte Annual Volcan Ubinas, 2016).

Beginning on 9 September 2016, both OVI and OVS noted an increase in seismic activity of LP, hybrid, and VT-type events (figure 42). On 13 September, OVS reported that steam plumes rose higher than 1,000 m above the summit for the first time in many months, and a minor ash emission was observed. OVI reported possible ash emissions in weekly reports on 12, 17, and 24 September. Emissions of bluish gas and steam were typical for the remainder of September (figure 43).

Figure (see Caption) Figure 42. An increase in several types of seismicity at Ubinas first appeared on 9 September 2016 after several months of quiet. This was followed by an ash emission on 13 September, and an explosion with ash on 3 October. Courtesy of IGP-OVS (Reporte N°31-2016, Actividad del volcán Ubinas, Resumen actualizado de la principal actividad observada del 01 al 18 de octubre).
Figure (see Caption) Figure 43. Bluish SO2-rich gas and steam emissions increased in frequency during the second half of September 2016 at Ubinas, as seen in this image taken from the village of Ubinas on 27 September 2016 by Melquiades Álvarez. Courtesy of IGP-OVS (Reporte Annual Volcan Ubinas, 2016).

Both OVI and OVS reported ash emissions from explosions on 3 October 2016 (figure 44). Seismic tremor, associated with ash emissions, lasted for nine and a half hours. The ash plume drifted NE, E, SE, and SW up to 2 km above the summit, according to OVS. Fumarolic activity then returned, with steam and bluish gases rising no more than 1,500 m above the crater rim for the remainder of October. The Buenos Aires VAAC noted the eruption reported by IGP, but was not able to identify volcanic ash from satellite data under clear skies. After peaking in early October at several hundred events per day, seismicity declined to below 50 events on 21 October, and then rose slightly to around 200 events per day for the rest of the month. Steam and gas emissions remained less than 500 m above the summit.

Figure (see Caption) Figure 44. An explosion at Ubinas on 3 October 2016 created a significant ash plume that rose 2,000 m above the crater rim, and drifted NE, E, SE, and SW. Photos by Melquiades Álvarez, courtesy of IGP-OVS (Reporte Annual Volcan Ubinas, 2016).

Three explosions with minor ash and gas (mostly SO2) were reported by IGP-OVS on 8 November (local time). NASA Goddard Space Flight Center reported a significant SO2 emission associated with this event. The ash plume rose to about 1,500 m above the crater rim (about 7.2 km altitude). Seismicity remained high, with 250-350 events per day for several days after the explosion before declining back to around 150 events per day by 15 November. Another explosion, with minor ash emissions that rose 500 m, was reported by both OVS and OVI on 17 November 2016. After a small spike in seismicity between 23 and 29 November, the number of seismic events dropped below 50 per day. OVS reported a small ash emission that rose 100 m above the summit and drifted NW on 6 December 2016. OVI noted a modest increase in seismicity between 6 and 15 December, but only sporadic emissions of water vapor and gas were detected for the remainder of the month.

Activity during January-September 2017. Gas and steam emissions remained below 500 m above the crater rim during January 2017. OVS reported an explosion at 0223 on 24 January, but could not confirm ash emissions due to darkness. Occasional emissions of steam and gas rose as high at 2 km above the summit crater, but they generally remained below 500 m. OVI observed five lahars during January, but no damage was reported. Seismicity remained below 60 events per day during the month, except for a few days during 8-12 January when the frequency increased to 100-150 events per day.

OVS reported sporadic low-density ash emissions throughout February 2017 (figure 45). They were accompanied, occasionally, by water vapor and bluish gas, and did not rise more than 1,500 m above the summit crater. Weather clouds obscured the summit for much of the month. OVI reported minor ash emissions on 4, 10, 14, and 18 February (figure 46). Seismicity fluctuated throughout the month from values as high as almost 70 events per day (8 February) to fewer than 10 events per day (10-19 February).

Figure (see Caption) Figure 45. Sporadic emissions of ash along with steam and magmatic gases were recorded in the IGP-OVS webcams at Ubinas on 4 and 9 February 2017. Courtesy of IGP-OVS (Reporte n.º 03-2017 - Actividad del volcán Ubinas, Resumen actualizado de la principal actividad observada del 01 al 15 de febrero de 2017).
Figure (see Caption) Figure 46. The OVI webcam captured a clear image of the 4 February 2017 ash emission. Courtesy of OVI (Reporte Semanal de Monitoreo: Volcan Ubinas, Reporte 06, Semana del 30 de enero al 05 febrero de 2017).

OVS reported only magmatic gas and steam emissions (with no ash) during March 2017, with plumes rising to a maximum height of 300 m above the summit crater. OVI noted possible diffuse ash emissions on 1 and 2 March, but only steam and gas emissions for the remainder of the month. They reported variable seismicity with the frequency of daily events ranging from less than 10 per day to almost 70, averaging about 30 events per day.

Seismic energy decreased significantly during April 2017. Sporadic steam emissions reached maximum heights of only a few hundred meters above the crater. This relative quiet enabled OVS scientist Melquiades Álvarez to make a brief inspection of the summit crater on 14 April where he observed intermittent steam emissions rising from the base of the summit crater (figure 47). No ash emissions were reported during April. OVI reported that the number of seismic events dropped consistently during April from a high of 20 daily events on 1 April, to fewer than 5 events per day at the end of the month.

Figure (see Caption) Figure 47. A view into the summit crater at Ubinas on 14 April 2017 revealed only sporadic steam emissions. Photo by Melquiades Álvarez; courtesy of IGP-OVS (Reporte n.º 07-2017-Actividad del volcán Ubinas, Resumen actualizado de la principal actividad observada del 01 al 15 de abril de 2017).

The reduction in activity continued during May 2017; steam and gas emissions became more sporadic and were rarely reported rising above 500 m over the summit crater. IGP-OVS reduced the alert level from Yellow to Green (2 to 1 on a 4-level scale) during the second half of the month. Seismicity reported by OVI fluctuated between 2 and 14 daily events. Ubinas remained quiet from June through September 2017, with only occasional minor fumarolic activity of steam or magmatic gas plumes that rose a few hundred meters above the summit crater (figure 48). Frequency of seismic events remained below 20 events per day through August and dropped to less than 10 per day in September.

Figure (see Caption) Figure 48. Virtually no emissions of any kind were reported from Ubinas after mid-July 2017, as seen in this image from the second half of August 2017. Courtesy of IGP-OVS (Reporte n.º 16-2017-Actividad del volcán Ubinas, Resumen actualizado de la principal actividad observada del 16 al 31 de agosto de 2017).

Geologic Background. A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Perú. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.

Information Contacts: Instituto Geofisico del Peru, Observatoria Vulcanologico del Sur (IGP-OVS), Arequipa Regional Office, Urb La Marina B-19, Cayma, Arequipa, Peru (URL: http://ovs.igp.gob.pe/); Observatorio Volcanologico del INGEMMET, (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, (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?lang=es).

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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.

Kermadec Islands

Floating Pumice (Kermadec Islands)

1986 Submarine Explosion

Tonga Islands

Floating Pumice (Tonga)

Fiji Islands

Floating Pumice (Fiji)

New Britain


Andaman Islands

False Report of Andaman Islands Eruptions

Sangihe Islands

1968 Northern Celebes Earthquake

Kawio Barat


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



Aleutian Islands

Possible 1986 Eruption Plume


False Report of New Volcano




La Lorenza Mud Volcano



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-Gibraltar Fracture Zone

Antarctica and South Sandwich Islands

Jun Jaegyu

East Scotia Ridge

 Special Announcements

Special Announcement Reports