**************************************************************** Bulletin of the Global Volcanism Network Volume 34, Number 8, August 2009 From: "Ed Venzke" <VENZKEE@xxxxxx> **************************************************************** Bulletin of the Global Volcanism Network Volume 34, Number 8, August 2009 http://www.volcano.si.edu/ Karymsky (Russia) New 14 August explosion crater formed on S side of upper summit Ebeko (Russia) Occasional steam plumes with ash from mid-2005 to mid-2009 Sakura-jima (Japan) May-October 2009, ongoing explosive eruptions Tungurahua (Ecuador) Vascun River map; lahar concerns; decreased activity in mid-2009 Telica (Nicaragua) Extensive degassing and sporadic ash explosions during 2006-2008 Lopevi (Vanuatu) Gray plume seen by pilot on 24 February 2008 Rabaul (Papua New Guinea) Modest earthquakes and ash plumes since mid-December 2008 Dieng Volcanic Complex (Indonesia) Seismicity before a 26 September 2009 phreatic eruption Barren Island (India) Almost daily thermal alerts and intermittent ash plumes January-September 2009 Ol Doinyo Lengai (Tanzania) Active hornitos and lava lake in summit crater observed 11-12 June 2009 Editors: Rick Wunderman, Edward Venzke, and Sally Kuhn Sennert Volunteer Staff: Paul S. Berger, Russell Ross, Hugh Replogle, Catie Carter, Ludmila Eichelberger, Robert Andrews, Margo Morell, Jacquelyn Gluck, and Stephen Bentley Karymsky Kamchatka Peninsula, Russia 54.05°N, 159.45°E; summit elev. 1,536 m All times are local (= UTC + 12 hours) This report covers 23 January to 9 September 2009, an interval with both thermal anomalies and ash plumes. A new explosion crater formed on the upper S flank on 14 August 2009. Many thermal anomalies were detected during 21 February to 1 March 2009 (figure 1). Figure 1. A plot of thermal anomalies registered during 1 February to 4 June 2009. Data provided in lower table. Courtesy of the Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences. During March 2009, Karymsky plumes were abundant (table 1). They were extending up to 200 km long on the 12th and 16th-17th. During 25 April and 19 May activity decreased although gas-and-steam emissions continued (figure 2). Table 1. Summary of plumes observed at Karymsky during 21 February to 4 June 2009. Data compiled from listed sources. 2009 Ash plume Source 21 Feb 150 km NE KEMSD; Tokyo VAAC 04 Mar 120 km SE KEMSD; Tokyo VAAC 05 Mar 75 km ENE; 64 km SE NOAA 16; NOAA 17 06 Mar 160 km E; 115 km E NOAA 17; NOAA 16 07 Mar 115 km SE NOAA 16 08 Mar 50 km SW NOAA 16; NOAA 17 09 Mar 50 km SW; 30 km E NOAA 17 12 Mar 200 km E KEMSD; Tokyo VAAC 13 Mar 130 km E NOAA 17; NOAA 16 16-17 Mar 200 km E KEMSD; Tokyo VAAC 26 Mar ash deposits to 30 km S KEMSD; Tokyo VAAC 04 Jun 30 km SE KEMSD; Tokyo VAAC Figure 2. Karymsky as seen on 18 April 2009. View was from the SE. Photo by A. Manevich. Volcanologists reported from a camp on Karymsky lake that at 1600 on 14 August 2009 they noticed a series of small ash emissions. They saw plumes rising to ~ 2.5 km altitude. As a result of the eruption, a crater formed on the volcano's upper S slope. The new explosion crater was round and deep, with a diameter of 70 m. At the time of the call the crater was still steaming to a height of 200 m above the crater (figure 3). Figure 3. Explosion crater on the S slope of Karymsky as seen on 18 August 2009 (four days after it formed). Photo by S. Chirkov. Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (Email: kvert@xxxxxxxxx, URL: http://www.kscnet.ru/ivs/); Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://emsd.iks.ru/~ssl/monitoring/main.htm), Sergei Chirkov and Alexander Manevich, IV&S FED RAS; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/). Ebeko Kuril Islands, Russia 50.68°N, 156.02°E; summit elev. 1,156 m All times are local (= UTC +11 hours) Our most recent report on Ebeko described minor seismic events between January-June 2005, accompanied by occasional plumes sometimes depositing minor ash (BGVN 30:06). Ebeko lacks a dedicated seismometer; therefore, the Kamchatkan Volcanic Eruption Response Team (KVERT) generally monitors the volcano with visual and satellite observations. The town of Severo-Kurilsk, ~ 7 km E of the summit, has been subjected to considerable environmental stress due to emissions in the past several years (Kotenko and Kotenko, 2009). The volcano is located at the N end of Paramushir Island, just S of the Kamchatka Peninsula. The island hosts five other volcanoes active in the Holocene, including Chikurachki, which was active in 2002, 2003, 2005, 2007, and as recently as September 2008. About 29 July 2005, KVERT raised the Concern Color Code from Green (the lowest level) to Yellow. During 22-29 July new fumaroles were noted in the active crater, and there was one explosion reported. This types of activity had not been observed since 1982. During 3-9 August fumarolic activity continued. During the week of 5-12 August 2005 weak fumarolic activity was noted, but no volcanic activity was visible on satellite imagery. Strong fumarolic activity occurred during 9-16 September, and gas temperatures reached 480°C. During the week 22-28 February 2006, KVERT reported that no significant changes in activity had been seen on satellite imagery or via ground observations for several months, so the Concern Color Code was reduced to Green. A weak scent of hydrogen sulfide and chlorine gas was sometimes noted in Severo-Kurilsk. No additional information was available about Ebeko until March 2007. According to a news article in RIA Novosti, on 22 March gas-and-steam clouds from the volcano rose to an altitude of 1.3-1.5 km. Nearby residents smelled sulfur and chlorine. Ebeko was not reported on again until February 2009. According to the Tokyo Volcanic Ash Advisory Center (VAAC) and KVERT, between 11 February and 18 June 2009, the volcano emitted a series of gas-and-steam plumes containing some ash (table 2, figure 4). During 29 January-23 February, the cumulative ashfall was 80 g/m^2. Table 2. Gas-and-steam plumes from Ebeko containing some ash between 11 February 2009 and 18 June 2009. Information was provided by the Tokyo Volcanic Ash Advisory Center based on an analysis of satellite imagery and information from Yelizovo Airport, and KVERT. Date (2009) Max. plume Plume drift altitude (km) direction 11 Feb 0.6 NE 17 Feb 1.2 SW 13 Mar 0.6 E 01 Apr-10 Apr 3.2-3.4 Various 10 Apr-17 Apr 1.5-2.7 SE 17 Apr-19 Apr 2-3 NE 24 Apr-01 May 1.2-3.5 Various 02 May -- -- 09 May-11 May 2.1-2.4 SW,SE 22 May 2.4 SE 09 Jun-10 Jun 2.7 -- 13 Jun 2.1 SW 13 Jun-18 Jun 1.7 -- Figure 4. Ash layers from Ebeko deposited in ~ 70 cm of snow and excavated and photographed on 26 February 2009. The layers were thin. More layers were deposited later (see text below). Courtesy of Leonid Kotenko (IV&S). Ashfall deposits in Severo-Kurilsk on 13-14, 18, 29, and 31 March 2009 (figures 5 and 6) were up to 2 mm deep. The town also experienced light ashfall on 5 and 22-23 April. Accordingly, on 3 April 2009 the Level of Concern Color Code was raised to Yellow. On 31 July, KVERT reported that activity had remained low since 13 July, and thus lowered the Level of Concern Color Code to Green. Figure 5. Ash cloud from Ebeko blowing towards Severo-Kurilsk, Paramushir Island, on 14 March 2009. Photographed by Tania Kotenko (IV&S). Figure 6. A photo showing an Ebeko explosion on 18 March 2009. Photographed by Leonid Kotenko (IV&S). Hazards and impacts on Severo-Kurilsk. Kotenko and Kotenko (2009) discussed the environmental impacts of Ebeko on Severo-Kurilsk. Threats include lahars, ashfalls, atmospheric poisoning from volcanic gases (particularly during periods of strong fumarolic activity), and the pollution of potable water supplies. Narrow river gorges descending the volcano can direct volcanic gas into Severo-Kurilsk, which lies in a lowland, accentuating the air pollution problem. The study noted the stresses on inhabitants during strong fumarolic activity of the kind seen during the 2- to 3-year-long intervals leading to eruptions. Historical eruptions occurred in 1793, 1833-34, 1859, 1934-35, 1967-71, and 1987-90. Geologic Summary. 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 of Ebeko contains strong solfataras and a large boiling spring. The central crater of Ebeko 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 of Ebeko, on the outer flanks of the cone, and in lateral explosion craters. Reference. Kotenko, Tatyana, and Kotenko, Leonid, 2009, Status of Ebeko volcano (Paramushir Island) and environmental impact of its eruptions, [in Russian] in Volcanism and Geodynamics: Content of 4th Russian symposium on volcanology and paleovolcanology: Yevgeny Gordeev (chief editor), IV&S Far East Division, Russian Academy of Sciences, 23-29 September 2009, v. 2, p. 613-617 [ISBN 978-5-902424-05-5]. Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (Email: kvert@xxxxxxxxx, URL: http://www.kscnet.ru/ivs/); Olga Girina (KVERT); Leonid Kotenko, Institute of Volcanology and Seismology (IV&S); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); RIA Novosti (URL: http://en.rian.ru/). Sakura-jima Kyushu, Japan 31.585°N, 130.657°E; summit elev. 1,117 m All times are local (= UTC + 9 hours) Our last reports on Sakura-jima (BGVN 31:06, 32:04, and 34:03) provided maps as well as a chronology of plume observations on this very active stratovolcano for the interval between 7 June 2006 and 24 April 2009. A small pyroclastic flow occurred on 9 April 2009. The current report continues the chronology of plume observations from 3 May to 3 October 2009 (table 3). Most of the plumes described since 20 March 2007 did not exceed 3 km altitude. The tallest plume recorded in the table, an ash plume on 30 May 2009, rose to about 4.6 km altitude. The 3 October eruption from Minami-dake crater was described as violent. From 1 January through 30 September 2009, no thermal alerts were recorded by MODVOLC. Table 3. Heights and drift of plumes and their character at Sakura-jima from 3 May 2009 to 29 September 2009. Courtesy of Tokyo Volcanic Ash Advisory Center, pilot reports, and the Japan Meteorological Agency (JMA). Dates are local. Date(s) Plume altitude/drift Other observations 03 May-04 May 2009 2.4-3.7 km Eruptions 09 May 2009 2.1-3 km/S Eruptions 12 May 2009 1.8 km/E Eruptions 19 May 2009 2.7 km/SE Eruptions 26 May 2009 2.7 km/NW Eruptions 30 May 2009 4.6 km/SE Explosion 31 May-01 Jun 2009 2.1-3.4 km/S Eruptions 07 Jun 2009 3 km Eruption 09 Jun 2009 2.4 km/N Eruption 12 Jun 2009 1.8 km -- 14 Jun-16 Jun 2009 2.4-2.7 km/SE, E Eruptions 24 Jun-30 Jun 2009 2.1-3.4 km/various Explosions 02-04, 06-07 Jul 2009 2.1-2.7 km/various Explosions 08, 10-15 Jul 2009 1.8-3.4 km/NE, E Explosions 15-22 Jul 2009 1.8-2.7/various Explosions. On 18-19 July airwaves exceeding 100 Pa were observed 3 km SW of the Showa crater. On 19 July, JMA raised the alert level to 3. 23, 27 Jul 2009 2.1-3/E, SW -- 24-25, 28 Jul 2009 -- Explosions 31 Jul-04 Aug 2009 2.1-3.4 km Explosions 05 Aug-10 Aug 2009 1.8-4 km/various Explosions, eruptions 12 Aug-17 Aug 2009 2.1-2.7 km/E, N Explosions, eruptions 19 Aug-25 Aug 2009 2.1-3 km/various Explosions 26-29 Aug, 01 Sep 2009 1.2-3.4 km/various Explosions 02 Sep-08 Sep 2009 1.2-2.7 km/various Explosions 09 Sep-15 Sep 2009 1.5-2.7 km/various Explosions 16, 18-19, 21 Sep 2009 1.5-2.7 km/various Explosions 23, 25, 27-29 Sep 2009 1.8-2.7 km/various Explosions 03 Oct 3 km Explosions at Minami-dake and Showa Late 2009 activity. According to JMA, Sakura-jima exploded violently from the Minami-dake crater at 1645 on 3 October 2009. The resulting Vulcanian plume rose up to 3 km above the crater and ballistics reached as far as 1.7 km away from the crater. This explosive eruption was the first from Minami-dake crater since 22 February 2009. The Showa crater was also active on the night of 2-3 October. Several explosions were observed then, and red hot materials were ejected up to 800 m from the rim. Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km wide Aira caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakura-jima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76. 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); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) 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/); Yukio Hayakawa, Gunma University, Faculty of Education, Aramaki 4-2, Maebashi 371-8510, Japan. Tungurahua Ecuador 1.467°S, 78.442°W; summit elev. 5,023 m Activity at Tungurahua began to decline in late June 2009 and continued this trend into early September. July and August 2009 were characterized by an absence of explosions, a marked decrease in ash emissions, and weak steam emissions. Although no new pyroclastic material was deposited in July or August 2009, the Instituto Geofisico-Escuela Politecnica Nacional (IG) still warned that heavy rains and the great amount of material on the upper slopes presented a danger of lahars and mudflows. Update on 22 August flood. Last month's report (BVGN 34:07) discussed a 22 August 2008 flood of the Vascun River (figure 7) after a natural dam failed. The flood destroyed two homes in the district of Las Ilusiones as well as the El Salado swimming pool complex, leaving two people injured and two others missing. Figure 7. Topographic map of the Vascun River on the N flank of Tungurahua, as well as the locations of the dam failure at the landslide and the districts of El Salado and Las Ilusiones, which were affected by the flood waters and associated sediment. "AFM" refers to an acoustical-flow monitor, a device to help detect processes such as mass wasting and pyroclastic flows along the river (Hadley and Lahusen, 1993). The heavy line along the river below the natural dam indicates the portion of the river through which the flood and debris traveled. Courtesy of IG. According to a 24 August 2008 article of the newspaper El Universo, strong rains began at approximately 2000 on 22 August and an earthquake was felt by residents in El Salado around 2345. El Universo stated that after the dam's failure, flood waters containing volcaniclastic material reached the El Salado area in ~ 5 minutes. The IG estimated that the flood had traveled at a velocity of 4.7-6.7 m/s. Two photographs showed bridges that had been visibly damaged by the event (figure 2 in BVGN 34:07). One bridge is located on the main road to Banos, adjacent to the city. The other bridge, 100 m upstream from the first, serves a secondary road. Officials plan on reviewing those bridge structures to determine whether they should be reinforced to avoid any flood-related damage in the future. El Universo reported that the two missing persons were young children who lived in one of the destroyed houses along the river in Las Ilusiones. Searches were unsuccessful and El Universo reported that the search concluded in September 2008. Geologic Summary. Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major volcanic edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Banos at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925. References: Hadley, K.C., and Lahusen, R.G., 1993. Technical manual for acoustic flow monitor. US Geol. Surv., Open-file Rep. 93-00, 19 pp.; Lahar-Detection System, USGS scientists create new method for detecting lahars (URL: http://volcanoes.usgs.gov/activity/methods/hydrologic/lahardetection.php). Information Contacts: Geophysical Institute (IG), Escuela Politecnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); El Universo (URL: http://www.eluniverso.com/). Telica Nicaragua 12.602°N, 86.845°W; summit elev. 1,061 m Activity at Telica during the second half of 2003 through January 2005 included incandescence and occasional ash explosions, after which only crater wall collapses and degassing occurred for the remainder of 2005 (BGVN 34:06). High seismicity and fumarolic activity continued in 2006, until a brief tremor episode accompanied by ash explosions in early August. Ash explosions during 2007 were reported in January-February, June, and October-November. Most observations in 2008 described degassing, but ash emissions were noted in February and July. The Nicaraguan Territorial Studies Institute (INETER) monitors activity; visits to the crater described below are by INETER staff. Activity during 2006. Seismicity during January-November 2006 remained high, in the range of about 3,000-6,000 micro-earthquakes/month (100-200/day). Collapses in the southern part of the crater were seen during a visit on 18 April, along with new fumarole locations in that area and one new fumarole on the N side. Similar activity, with strong gas emmissions occurred on 27 April. An unusual tremor episode that began on 3 August prompted a visit by INETER scientists the next day. The team found that small ash explosions on 4 August were coming from a new vent that had opened in the W part of the crater. Incandescent rocks were also being ejected. Ashfall was reported in the communities of Cristo Rey and Las Maria, NW of the volcano. In addition, gas emissions were rising from the area of an opening, since covered by landslides, that formed in May 1999. Tremor ended on the 5th, but another ash-and-gas explosion was reported on 6 August. Two more new fumaroles, in the N and W part of the crater floor, were seen on 6 and 28 September. Seismicity changed character on 25 November, with increased tremor and volcano-tectonic earthquakes. The high but variable seismic activity continued during December, when micro-earthquakes were recorded at a rate of about 400/day. Small seismically-detected explosions took place on 11 and 27 December, although the amount of ash and it's distribution was not known. Activity during 2007. The high levels of seismicity and swarm episodes that began in November 2006 declined during February 2007. Micro-earthquakes averaged 80-135/day in January-February. A small phreatic explosion was recorded on 9 January, followed on the 10th by explosions of gas and ash. The plume on 9 January reached an initial altitude of 1.5 km (500 m above the summit) and drifted W before rising further. More small explosions occurred on 6, 15, and 17 February. Continuous ash emissions rising to 1.5 km altitude were visible on a webcam during the 15 February activity; satellite imagery showed a plume drifting SW and a thermal hotspot at the summit. Daily micro-earthquake counts throughout the rest of the year ranged from 64 to 180, until the seismic station ceased operating in December. INETER observers at the crater on 12 June saw abundant gas emissions from multiple areas within the crater, and explosions that may have contained ash. During a visit on 14 August landslides were noted from the NW side of the crater walls, as were 50-cm cracks in the S wall. Large volumes of gray gas emissions were reportedly causing acid rain damage to local vegetation, and affecting area residents. Sporadic gas-and-ash explosions were reported in the last week of October and during November, causing ashfall in Quezalguaque and other locations around the volcano. Activity during 2008. A fieldwork visit to the crater on 16 January 2008 revealed only gas emissions with jet sounds; a local resident reported similar observations. A farmer near the volcano reported to INETER that there was a heavy outflow of gas and ash on 18 February that affected the W and NW flanks; by the time of a 22 February visit only gas emissions were occurring. Gas emissions accompanied by jetting sounds were the only activity noted during subsequent visits on 10 March and 25 April. Small gas-and-ash explosions took place in early July. However, again only gas output was observed during crater visits on 22 July, 18 August, 9 September, 26 November, and 16 December (figure 8). Figure 8. Strong gas emissions from Telica, September 2008. Courtesy of INETER. Seismic data began being reported again in February 2008. Average daily micro-earthquake counts, reported monthly, were 90-150 from February through July. August seismicity was not reported, but there were only 80 events/day in September, and 50 events/day in October. The seismograph was not operational in November or December. Geologic Summary. Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. The Telica 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 Telica 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 1,061-m-high 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 SE of Telica, 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: Wilfried Strauch, Instituto Nicaraguense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/geofisica/geofisica.html); Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/). Lopevi Vanuatu 16.507°S, 168.346°E; summit elev. 1,413 m All times are local (= UTC + 11 hours) Our previous report on Lopevi (BGVN 32:05) noted eruptions and thermal anomalies in April and May 2007. No additional thermal anomalies were observed by MODVOLC's satellite system from 14 May 2007 through 25 September 2009. Based on a pilot report, the Wellington Volcanic Ash Advisory Centre reported that at 1404 on 24 February 2008, a thick grayish plume from Lopevi rose to an altitude below 3 km and drifted 9 km E. Volcanic ash was not visible on satellite imagery. By 1650 activity was subsiding, and the plume was lower. At 0732 on 25 February the pilot did not detect any significant activity. Geologic Summary. The small 7-km-wide conical island of Lopevi, known locally as Vanei Vollohulu, is one of Vanuatu's most active volcanoes. A small summit crater containing a cinder cone is breached to the NW and tops an older cone that is rimmed by the remnant of a larger crater. The basaltic-to-andesitic volcano has been active during historical time at both summit and flank vents, primarily along a NW-SE-trending fissure that cuts across the island, producing moderate explosive eruptions and lava flows that reached the coast. Historical eruptions at the 1413-m-high volcano date back to the mid-19th century. The island was evacuated following major eruptions in 1939 and 1960. The latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow that swept to the sea and a lava flow that formed a new peninsula on the western coast. Information Contacts: NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); Hawai'i Institute of Geophysics and Planetology (HIGP) 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/); Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html). Rabaul New Britain, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m This report updates our discussion of Rabaul caldera's behavior after mid-December 2008 (BGVN 33:11). Following the large 1994 eruption (Blong and McKee, 1995; Blong, 2003; Nairn and others, 1995), the ongoing eruptions have been focused at one vent along the caldera's E side at the Tavurvur cone. Between mid-December 2008 and 30 September 2009, minor eruptions at Tavurvur continued a period of intermittent activity that began in August 2006 (BGVN 31:02). Characteristic activity during this interval consisted of intermittent emissions of ash plumes and less frequent explosions sometimes ejecting incandescent lava fragments. During mid-December 2008 through January 2009, earthquakes were weak to moderate, but increased to moderate to high in March before decreasing again after 10 April. The earthquakes were dominated by events associated with ash emissions. Ground deformation measurements by GPS and tide gauge stations registered deflation during mid-December 2008 through mid-March 2009, sometimes with modest uplift. The water-tube tiltmeter data showed a modest down-tilt toward the caldera. In mid-March deflation slowed and then ceased. Deformation was stable until September 2009, when deflation increased slightly. According to the Rabaul Volcano Observatory (RVO), during much of the above 10-month period, white plumes and gray ash plumes from Tavurvur rose a few hundred to several thousand meters above the crater. Glow was seen most nights and incandescent tephra was ejected. RVO reported that, on 11 January, two small vents opened one-quarter of the way up the SW flank of Tavurvur and began to emit ash. Ash emissions from the volcano ranged from occasional to sustained over long periods during mid-December 2008 through April 2009 and, during this period, light-to-moderate ash fell on nearby communities, including Rabaul town (3-5 km NW). During 5-9 January 2009 ashfall caused Air Niugini to suspend all its flights to Tokua airport (about 20 km SE) and, according to a news article, a local shipping company offered to take up to 400 passengers to an airport in New Ireland Province, an area not affected by the ash plumes. In May through July, the amount of ashfall decreased, and periods of no ash were noted, but ashfall again increased somewhat in September. A MODIS satellite image of an ash plume was taken on 28 August 2009 (figure 9). Figure 9. Rabaul volcano on the island of New Britain released a plume of ash and/or steam on 28 August 2009, as the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this true-color image. The volcanic plume blews NW. Unlike the nearby clouds, the plume is slightly darker in color, with more diffuse outlines. Courtesy of NASA Earth Observatory. Although the weather often precludes satellite observations, the combination of reports from the Darwin Volcanic Ash Advisory Centre (VAAC) and the RVO can be tabulated to provide a sense of the ongoing activity (table 4). Table 4. Ranges of ash plume altitudes and drift directions from Rabaul's Tavuvur cone between 10 December 2008 and 18 September 2009. A similar table was presented for the period 1 May-10 December 2008 in BGVN 33:11. Data courtesy of RVO and the Darwin VAAC. Dates Plume Plume direction; Notes altitude extent from source 10 Dec-26 Dec 2008 1.7-3 km NE, ENE, ESE, SE, W gray ash, roaring noises, explosions, incandescent lava ejections 30 Dec-30 Jan 2009 1.7-2.4 km W, NW, NNW, N, NE, SE, SW gray ash 14 Jan-03 Feb 2009 1.7-3 km N, NE, SE, SW gray ash 04 Feb-23 Feb 2009 1.8-3 km SE, S, W, NW 02 Mar-26 Mar 2009 1-3 km N, NW, SE white and gray ash; blue vapor visible between ash emissions 27 Mar-26 Apr 2009 0.5-3 km S, SW, SE, NW, NE, W; white with occasional gray 35-120 km or brown plumes 27 Apr-20 May 2009 2.4-3 km NE, E, SE, SW; 30-40 km pale gray ash, white with occasional blue plumes 21 May-21 Jun 2009 1-4.3 km S, E, SE, NW; 20-75 km pale gray ash, white with occasional blue plumes 22 Jul-02 Sep 2009 1.5-3 km N, E, NW,SW, S; 25-280 km -- 04 Sep-18 Sep 2009 1.5-2.4 km N, NW; 35-260 gray ash and white plumes; ashfall in Rabaul town (3-5 km NW) MODVOLC satellite thermal alerts were common at Tavurvur during the year ending 7 October 2009. Alerts during this interval sometimes occurred multiple times per day but with frequent gaps of days, and in one case, about a month. A similar pattern was noted during 16 November to 23 July 2007 (BGVN 32:06 and 29:06). References: Blong, R. and McKee, C., 1995, The Rabaul eruption 1994: Destruction of a town: National Hazards Research Center, Macquarie University, Australia. Blong, R., 2003, Building damage in Rabaul, Papua New Guinea, 1994: Bull. Volc., v. 65, no. 1 [ISSN 0258-8900 (Print) 1432-0819 (Online)] Nairn, I.A., McKee, C.O., Talai, B. and Wood, C.P., 1995, Geology and eruptive history of the Rabaul Caldera area, Papua New Guinea: Jour. Volcanol. Geotherm. Res., v. 69, p. 255-284. Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay and was formed about 1400 years ago. An earlier caldera-forming eruption about 7100 years ago is now considered to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the northern and NE caldera rims of Rabaul. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city. Information Contacts: Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) 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/); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/). Dieng Volcanic Complex Java, Indonesia 7.20°S, 109.92°E; summit elev. 2,565 m This report describes a phreatic eruption at Dieng on 26 September, an event preceded by increased seismicity. Previously, a phreatic eruption on 15 January 2009 followed the burial and sealing of the floor of the Sibanteng crater by landslides (BGVN 34:04). In the past, a large number of eruptions from the Dieng complex have been minor phreatic events (Germanovich and Lowell, 1995; van Bergen and others, 2000). Monitoring is carried out by the Center for Volcanology and Mitigation of Geologic Disasters (CVGHM) from the village of Karang Tengah. Seismic activity within the complex began in early September 2009. Four deep volcanic and two shallow volcanic earthquakes preceded a phreatic eruption on 26 September. On that day CVGHM reported a thunderous noise from Dieng heard up to 2 km away. The next day, a phreatic eruption from an unspecified crater ejected mud as far away as 140 m S. The deposits were as thick as 10 cm near the vent and 1 cm near the farthest point of deposition. Scientists did not observe an increase in the concentration of poisonous gases at either the vent or in the surrounding area. Reference: Germanovich, L.N., and Lowell, R.P., 1995, The mechanism of phreatic eruptions: J. Geophys. Res., v. 100 (B5), p. 8417-8434. van Bergen, M.J., Bernard, A., Sumarti, S., Sriwana, T., and Sitorus, K., 2000, Crater lakes of Java: Dieng, Kelud and Ijen, Excursion Guidebook, IAVCEI General Assembly, Bali 2000 (URL: www.ulb.ac.be/sciences/cvl/DKIPART1.pdf). Geologic Summary. 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 AD. 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 volcanic gas emission has caused fatalities and is a hazard at several craters. The abundant thermal features that dot the plateau and high heat flow make Dieng a major geothermal prospect. Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/). Barren Island Andaman Islands, India 12.278°N, 93.858°E; summit elev. 354 m Our previous report on Barren Island (BGVN 33:11) noted frequent thermal anomalies recorded by MODIS instruments and processed by the MODVOLC system through the last half of 2008. This report notes activity between 1 January and 15 September 2009. Ash plumes from Barren Island were a frequent occurrence during January 2009, and intermittent from February through 15 September 2009 (table 5). MODVOLC thermal anomalies remained frequent, usually daily, during 1 January 2009 through 15 September 2009. Table 5. Ash plumes from Barren Island, 4 January 2009-14 September 2009. Courtesy, Darwin Volcanic Ash Advisory Centre, based on satellite imagery, SIGMET notices, and pilot observations. Date (2009) Maximum Plume Drift Altitude and Distance 04 Jan-06 Jan 2.4 km SW, NW 07-08, 10-11 Jan 1.8-2.4 km W, SW 18 Jan-19 Jan 3 km NNE, NE 21 Jan 2.4 km N, NW 31 Jan -- S (~ 55 km) 05 Feb 3 km SSE 20 Feb-21 Feb 2.4 km WNW, NW, N (~ 75-90 km) 25 Mar-26 Mar 2.1 km S (110 km) 23 Apr-25 Apr 2.4 km NE, E, SE (45-65 km) 20 May 2.1 km NE (75 km) 19 Jul-20 Jul 1.5 km NE (45-65 km) 13 Sep-14 Sep 2.4 km W, NE (20-100 km) Geologic Summary. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of a volcano that rises from a depth of about 2250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the west, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. The morphology of a fresh pyroclastic cone that was constructed in the center of the caldera has varied during the course of historical eruptions. Lava flows fill much of the caldera floor and have reached the sea along the western coast during historical eruptions. 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/); Hawai'i Institute of Geophysics and Planetology (HIGP) 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/). Ol Doinyo Lengai Tanzania 2.764°S, 35.914°E; summit elev. 2962 m All times are local (= UTC + 3 hours) Our most recent report on Ol Doinyo Lengai discussed observations from several climbing groups and pilots during April 2008 through January 2009 (BGVN 34:05). This report reflects observations made during 11-12 June 2009 (figures 10-14) by a scientific team composed of Maarten deMoor (University of New Mexico), David Hilton and Peter Barry (Scripps Institution of Oceanography, UCSD), Fredrick Mangasini (University of Dar es Salaam), Carlos Ramirez (University of Costa Rica), and Tobias Fischer (University of New Mexico). Figure 10. The ash cone at Ol Doinyo Lengai (approximately 30 m high) is located in the pre-September 2007 crater area. The first explosive eruption of the ash cone occurred on 10 September 2007. The currently actively degassing crater is on the left of this picture to the E. Photo taken looking S on 11-12 June 2009. Courtesy of T. Fischer. Figure 11. View of active crater at Ol Doinyo Lengai, looking N on 11-12 June 2009. The crater is approximately 80 m deep. Note the collapsed hornitos on the crater floor. Courtesy of T. Fischer. Figure 12. Active carbonatite lava lake in the NW part of the Ol Doinyo Lengai crater on 11-12 June 2009. Photo looking NW. The lava was convecting vigorously with occasional spill-over during the observations. Courtesy of T. Fischer. Figure 13. Installation of the plume sampling equipment on 11 June at the edge of the Ol Doinyo Lengai crater; photo looking E. The equipment was used to collect aerosols and to sample sulfur dioxide, hydrogen sulfide, and carbon dioxide in the plume. Courtesy of T. Fischer. Figure 14. Stratigraphic section of the S crater at Ol Doinyo Lengai, showing the complete sequence of the 2007-2008 explosive eruptions; photo looking W. The total thickness was 84 cm, including layers consisting of ash and lapilli. Courtesy of T. Fischer. The team stated that on 11-12 June 2009, "carbonatite is currently erupting from hornitos and a lava lake [sits] at the bottom of the new (September 2007) crater" (figure 12). These conditions demonstrated both the establishment of a lava lake, less explosive activity, and more passive lava emissions on the crater floor. Comparison of satellite imagery from July 2004 (figure 15) and September 2009 (figure 16) provided by the NASA Earth Observatory website, showed the summit changes caused by the switch from generally effusive eruptions to a series of explosions beginning in 2007 (BGVN 32:11, 33:02). In September 2007, explosive eruptions began. sending ash thousands of meters into the air. Ash also covered the surrounding landscape, forcing local residents to flee with their livestock. Explosive eruptions continued into 2008, building a ring of fragmental material over 100 m high on the edge of the N crater. In satellite imagery acquired 12 September 2009 by the Advanced Land Imager (figure 16), the new cone and its deep concentric crater are clearly visible. Figure 15. Satellite image acquired 16 July 2004 shows Ol Doinyo Lengai's summit after a long period of effusive eruptions. Beginning in 1983, lava began to fill the crater of an ash cone that formed during explosive eruptions in 1966-1967. Over time, the lava filled the crater and created a large flat platform. Dark areas on the crater floor are recent lava flows (days to weeks old), while the beige and white regions are older lava that have reacted with rain and moisture in the atmosphere. In 1998, lava began to spill over the rim of the crater to the north and east. These lava flows are visible as beige fingers radiating down the sides of the mountain. Dark green vegetation covers the upper slopes. Image is from the Advanced Land Imager (ALI) aboard the Earth Observing-1 satellite; courtesy of NASA Earth Observatory. Figure 16. In this satellite image of Ol Doinyo Lengai, acquired 12 September 2009, the new cone and crater (essentially a ring-shaped structure) are clearly visible in the center of the image. The dark spot in the crater may be fresh lava erupted from a new volcanic vent. Gray ash covers the volcano and much of the surrounding landscape. Image is from the the Advanced Land Imager; courtesy of NASA Earth Observatory. Reports on Fredrick Belton's website described the following visits during the summer of 2009. Table 6 is a continuation of the one in BGVN 35:05. A final statement on the website notes that, although activity appeared to have returned in August 2009 to the typical gentle eruptions of fluid natrocarbonatite lava, no samples of the new flows have been obtained for analysis due to their inaccessibility deep inside the steep-walled crater. Therefore, it remains uncertain how compositionally similar the new inaccessible lavas are compared to those produced prior to the 2007-2008 eruption. Table 6. Summary of selected observations describing Ol Doinyo Lengai during June-August 2009. The observers indicated continuing small effusive eruptions within the pit crater. Observation key: CV=climbed volcano; F=flank observations; A=aerial observations/photos from crater overflight. Courtesy of F. Belton. Dates Observer(s) Observations 11-12 Jun 2009 Maarten deMoor, (CV) see text above David Hilton, Peter Barry, Fredrick Mangasini, Carlos Ramirez, Tobias Fischer July 2009 David Gregson (CV) no significant activity viewed, but heard sounds of activity at depth late Aug 2009 Thomas Holden (CV) viewed active lava flows 12 Sep 2009 Ben Wilhelmi (A) see text below Ben Wilhelmi, a commercial pilot working in the region, sent us some recent aerial photographs taken on 12 September 2009. We present two of those photos featuring overviews of the summit complex (figures 17 and 18). Figure 17. Aerial photo of Ol Doinyo Lengai looking approximately SE. The active N crater and the ring of fragmental material deposited by the 2007-2008 eruptions is in the left center of the image. The summit appears to the right. Taken 12 September 2009 and provided courtesy of Ben Wilhelmi. Figure 18. Aerial photo of Ol Doinyo Lengai looking approximately NNE. The active N crater is in the distance (to the left of the photo's center). Compared to the N crater, the quiet S crater is larger and more pan-shaped. The sharp peak of the summit is prominent between the two craters. Taken 12 September 2009; courtesy of Ben Wilhelmi. Geologic Summary. The symmetrical Ol Doinyo Lengai stratovolcano is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent volcano, known to the Maasai as "The Mountain of God," rises abruptly above the broad plain south of Lake Natron in the Gregory Rift Valley. The cone-building stage of the volcano ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatitic and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra eruptions and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater and occasionally down the upper flanks. The depth and morphology of the northern crater have changed dramatically during the course of historical eruptions, ranging from steep crater walls about 200 m deep in the mid-20th century to shallow platforms mostly filling the crater. Long-term lava effusion in the summit crater beginning in 1983 had by the turn of the century mostly filled the northern crater; by late 1998 lava had begun overflowing the crater rim. Information Contacts: Tobias Fischer, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USA (Email: fischer@xxxxxxx); Frederick Belton, Developmental Studies Department, PO Box 16, Middle Tennessee State University, Murfreesboro, TN 37132, USA (URL: http://www.mtsu.edu/~fbelton/ and http://www.oldoinyolengai.org; Email: oldoinyolengai@xxxxxxxxxxx); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); Ben Wilhelmi (URL: http://www.benwilhelmi.com/). ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
