******************************************************** SI/USGS Weekly Volcanic Activity Report 23-29 April 2008 ******************************************************** Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Masaya, Nicaragua Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Fuego, Guatemala | Kanlaon, Negros I | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Llaima, Central Chile | Manam, Northeast of New Guinea (SW Pacific) | Nevado del Huila, Colombia | Rabaul, New Britain (SW Pacific) | Sakura-jima, Kyushu (Japan) | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Tungurahua, Ecuador | Ubinas, Perú The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network. Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. New Activity/Unrest MASAYA Nicaragua 11.984°N, 86.161°W; summit elev. 635 m Based on observations of satellite imagery and pilot observations, the Washington VAAC reported that an ash plume from Masaya rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SW on 29 April. Geologic Summary. Masaya is one of Nicaragua's most unusual and most active volcanoes. It is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high that is filled on its NW end by more than a dozen vents erupted along a circular, 4-km-wide fracture system. The twin volcanoes of Nindiri and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters. A major basaltic Plinian tephra was erupted from Masaya about 6,500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the N caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted several attempts to extract the volcano's molten "gold." Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m The Darwin VAAC reported that low-level ash-and-steam plumes from Batu Tara were observed on satellite imagery during 25-26 April. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m The Washington VAAC reported that an ash plume from Fuego was visible on satellite imagery on 23 April and drifted SW. On 28 April, INSIVUMEH reported that explosions (1 per hour) produced ash plumes to an altitude of 4.4 km (14,400 ft) a.s.l. The plumes drifted 5 km SW. The explosions produced noises audible 15 km away and shock waves that rattled windows and structures in nearby villages. Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html KANLAON Negros I 10.412°N, 123.132°E; summit elev. 2435 m According to news articles, PHIVOLCS lowered the Alert Level for Kanlaon to 0 on 25 April. Seismic activity was at background levels during 5 March-25 April, with 0-3 earthquakes per day. Mt. Kanlaon Natural Park opened for mountaineering activities; however visitors were warned that the risk of entering the 4-km permanent danger zone remained high. Geologic Summary. Kanlaon volcano (also spelled Canlaon), the most active of the central Philippines, forms the highest point on the island of Negros, about 500 km ESE of Manila. The massive stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The summit of Kanlaon contains a broad northern crater with a crater lake and a smaller, but higher, historically active crater to the south. Historical eruptions, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano. Source: Sun Star http://www.sunstar.com.ph/static/bac/2008/04/30/news/mt..kanla.on.open.for.trekking.html KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that seismic activity at Karymsky was above background levels during 18-25 April. Observations of satellite imagery revealed that a thermal anomaly was present in the crater on 18 and 21 April. Based on seismic interpretation, weak ash-and-gas explosions may have occurred on 20 and 21 April and produced plumes to altitudes of 2.6-3.4 km (8,500-11,200 ft) a.s.l. Volcanologists reported seeing ash plumes to an altitude of 2 km (6,700 ft) a.s.l. during 20-23 April. The Level of Concern Color Code remained at Orange. Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m Based on observations during helicopter overflights, visual observations from HVO and National Park Service (NPS) crews, and web camera views, HVO reported that during 23-29 April lava flowed SE through a lava tube system underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex to the Waikupanaha ocean entry. Incandescence from breakouts along the lava-tube system was noted on 23 April. During the reporting period, Kilauea summit earthquakes were located beneath the Halema'uma'u vent, beneath the S Kilauea caldera, NW of Pahala, along the S-flank faults, and along the SW rift zone. The eruption from the vent in Halema'uma'u Crater continued to produce white plumes with minor ash content that drifted mainly SW. During most nights incandescence was seen at the base of the plume. Seismic tremor was elevated. Sulfur dioxide emission rates from the summit area have been elevated at 2-4 times background values since early January. On 28 April, the emission rate at the summit was 1,910 tonnes per day, compared to a background rate of 150-200 tonnes per day. According to news articles, Hawaii Volcanoes National Park closed during 24-25 April due to elevated levels of sulfur dioxide. About 2,000 people were evacuated from the Park. Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island. Sources: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/, Associated Press http://www.kpua.net/news.php?id=14652 LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m SERNAGEOMIN reported that on 24 April, seismicity from Llaima increased and gas-and-ash plumes associated with explosions rose to an altitude of 4.6 km (15,100 ft) a.s.l. No morphological changes to the summit were observed during an overflight on 25 April, except for a small increase of the diameter of the SE crater. Bluish gas was emitted from the main crater. Geologic Summary. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other to the SE. The massive 3,125-m-high, glacier-covered stratovolcano has a volume of 400 cu km. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following eruption of the 24 cu km Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7,200 years ago, construction of the present edifice began, characterized by Strombolian, hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/ MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m Based on observations of satellite imagery and information from RVO, the Darwin VAAC reported that a diffuse plume from Manam rose to an altitude of below 3 km (10,000 ft) a.s.l. and drifted NW. Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5365 m INGEOMINAS reported that seismicity from Nevado del Huila decreased during 23-29 April. No significant morphological changes to the summit were noted during an overflight on 29 April, although the NE and NW flanks could not be seen due to strong winds. The Alert Level remains at Orange (on a 4-color scale where Orange is second highest). Geologic Summary. Nevado del Huila, the highest active volcano in Colombia, is an elongated N-S-trending volcanic chain mantled by a glacier icecap. The andesitic-dacitic volcano was constructed within a 10-km-wide caldera. Volcanism at Nevado del Huila has produced six volcanic cones whose ages in general migrated from south to north. Two glacier-free lava domes lie at the southern end of the Huila volcanic complex. The first historical eruption from this little known volcano took place in the 16th century. Two persistent steam columns rise from the central peak, and hot springs are also present. Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co// RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 23-29 April ash and ash plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 1.7-2.7 km (5,600-8,900 ft) a.s.l. and drifted N, NE, E, SE, and SW. Incandescence at night at the summit, intermittent roaring noises, and occasional explosions were reported. Ashfall measured over 1 cm thick nearby and E of Tavurvur during 23-24 April and was noted in other areas downwind during 25-29 April. Incandescent fragments were propelled from the summit at night during 27-28 April. 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. 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 E, where its floor is flooded by Blanche Bay.Two major Holocene caldera-forming eruptions at Rabaul took place as recently as 3,500 and 1,400 years ago. Three small stratovolcanoes lie outside the northern and NE caldera rims. 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. Source: Steve Saunders and Herman Patia, Rabaul Volcano Observatory (RVO) SAKURA-JIMA Kyushu (Japan) 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that eruption plumes from Sakura-jima rose to an altitude of 2.4 km (8,000 ft) a.s.l. The plumes drifted SE on 27 April and W on 30 April. 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 was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago 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. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m Based on observations of satellite imagery, the Washington VAAC reported that an ash plume from Santa María's Santiaguito lava dome complex rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted SW on 25 April. On 28 April, INSIVUMEH reported that weak explosions produced ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l. and drifted W. Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that seismic activity at Shiveluch was above background levels during 18-25 April. Observations of satellite imagery revealed that a thermal anomaly was present in the crater during 18 and 20-23 April. According to video footage and visual observations, fumarolic activity from the lava dome occurred during 21-23 April. The Level of Concern Color Code remained at Orange. Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. During the 1990s, intermittent explosive eruptions took place from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m The IG reported that although visual observations were occasionally limited due to cloud cover during 22-28 April, ash-and-steam plumes from Tungurahua were spotted and rose to altitudes of 6-8 km (19,700-26,200 ft) a.s.l. Ashfall was reported in areas downwind on 23, 25, and 28 April. On 22 April, a small lahar descended the Mapayacu drainage to the SW. On 23 April, explosions accompanied by "cannon shot" noises produced ash plumes that drifted WSW and caused windows to rattle in areas to the NW, W, and SW. Blocks rolled 600 m down the flanks. On 25 April, fumarolic activity was noted on the interior of the NE crater rim. Sounds resembling blocks rolling down the flanks were reported. Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. 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. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano. Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/ UBINAS Perú 16.355°S, 70.903°W; summit elev. 5672 m Based on SIGMET reports and observations of satellite imagery, the Buenos Aires VAAC reported that an ash plume from Ubinas rose to altitudes of 5.5-9.1 km (18,000-30,000 ft) a.s.l. and drifted SE and S on 23 April. Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, 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 of Ubinas extend 10 km from the volcano. Widespread Plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html +++++++++++++++++++++++++++++++++++++ Sally Kuhn Sennert SI/USGS Weekly Volcanic Activity Report Editor Global Volcanism Program http://www.volcano.si.edu/reports/usgs/ Smithsonian Institution, National Museum of Natural History Department of Mineral Sciences, MRC-119 Washington, D.C., 20560 Phone: 202.633.1805 Fax: 202.357.2476 ============================================================== 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. ==============================================================
