****************************************************** SI/USGS Weekly Volcanic Activity Report 8-14 July 2009 ****************************************************** Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Manda Hararo, Northeastern Africa | Mayon, Luzon | San Miguel, El Salvador | Sarychev Peak, Matua Island | Shishaldin, Fox Islands Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Dukono, Halmahera | Fuego, Guatemala | Kilauea, Hawaii (USA) | Pacaya, Guatemala | Rabaul, New Britain | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) 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 MANDA HARARO Northeastern Africa 12.17°N, 40.82°E; summit elev. 600+ m A large sulfur dioxide plume and several thermal anomalies from Manda Hararo that were detected in satellite imagery during 28-30 June prompted a science team to visit the area on 4 July. After conducting ground-based and aerial observations for approximately 2 hours, they reported that the eruption occurred near the August 2007 eruption site, and was possibly bigger than that event. No active lava effusion was seen, but steaming was observed from the 4-5 km-long fissure that, because of high temperatures, had to be observed from a distance. They also saw new predominantly 'a'a lava flows that were 2-3 m thick. The fissure was lined with scoria ramparts 30-50 m high. Temperature measurements taken with a FLIR (Forward Looking Infrared Radiometer) indicated that the lava flow had cooled significantly with temperatures between 30 and 120 degrees Celsius at the surface. A maximum temperature of 238 degrees Celsius was measured during aerial observations. Geologic Summary. The southernmost axial range of western Afar, the Manda Hararo complex is located in the Kalo plain, SSE of Dabbahu volcano. The massive complex is 105 km long and 20-30 km wide, and represents an uplifted segment of a mid-ocean ridge spreading center. A small basaltic shield volcano is located at the northern end of the complex, south of which is an area of abundant fissure-fed lava flows. Two basaltic shield volcanoes, the largest of which is Unda Hararo, occupy the center of the complex. The dominant part of the complex lies to the south, where the Gumatmali-Gablaytu fissure system is located. Voluminous fluid lava flows issued from these NNW-trending fissures, and solidified lava lakes occupy two large craters. Lava flows from the Gablaytu and Manda shield volcanoes overlie 8000-year-old sediments. Hot springs and fumaroles occur around Daorre lake. The first historical eruption from Manda Hararo produced fissure-fed lava flows in 2007. Sources: Gezahegn Yirgu, Addis Ababa University (AAU), Simon Carn http://www.volcarno.com/ MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m PHIVOLCS reported that a "cone-shaped pile of hot, steaming old rocks," possibly from a previous eruption of Mayon, were seen during an overflight on 8 July and may be the source of recent summit incandescence. On 9 July, a leveling survey revealed that 1 cm of uplift previously measured during 15-22 June had been sustained. Incandescence at the summit crater had also intensified and was visible from the Lignon Hill Observatory (about 11 km SSE) without the aid of telescopes. Steam emissions were also noted. On 10 July, PHIVOLCS raised the Alert Level for Mayon from 1 (low level unrest) to 2 (moderate unrest) on a scale of 0-5. Geologic Summary. Beautifully symmetrical Mayon volcano, which rises to 2,462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes that average 35-40° and is capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from Strombolian to basaltic Plinian. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1,200 people and devastated several towns. Eruptions that began in February 2000 led PHIVOLCS to recommend on 23 February 2000 the evacuation of people within a radius of 7 km from the summit in the SE and within a 6 km radius for the rest of the volcano. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/ SAN MIGUEL El Salvador 13.434°N, 88.269°W; summit elev. 2130 m Servicio Nacional de Estudios Territoriales (SNET) reported that the amplitude of seismic events from San Miguel had decreased during 9-13 July, but RSAM values remained above the background average. Access to areas within a 2-km-radius was restricted. Geologic Summary. The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. A broad, deep crater that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit of the towering volcano, which is also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic volcano have fed a series of fresh lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the N, W, and SE sides. The SE-flank lava flows are the largest and form broad sparsely vegetated lava fields. Source: Servicio Nacional de Estudios Territoriales (SNET) http://www.snet.gob.sv/ SARYCHEV PEAK Matua Island 48.092°N, 153.20°E; summit elev. 1496 m Based on analyses of satellite imagery, SVERT reported that diffuse gas-and-steam plumes from Sarychev Peak were seen on satellite imagery during 8-10 and 12 July. Plumes drifted 15 km E on 8 July. The plumes seen on 9 July drifted 50 km E and may have contained some ash. Gas-and-ash plumes drifted 40 km E on 13 July and 25 km W and NW on 14 July. Geologic Summary. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5 km wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows descend all sides of Sarychev Peak and often form capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760's and include both quiet lava effusion and violent explosions. The largest historical eruption of Sarychev Peak in 1946 produced pyroclastic flows that reached the sea. Source: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/rus/labs_vulcan_hazard.php SHISHALDIN Fox Islands 54.756°N, 163.97°W; summit elev. 2857 m On 10 July, AVO reported that a distinct thermal anomaly in Shishaldin's summit crater observed intermittently since January 2009 became more intense during the previous month. AVO raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. AVO also noted that seismicity had not increased, deformation was unchanged, and satellite observations showed no significant sulfur dioxide gas emissions. Some reports of steaming from the summit crater were received. Geologic Summary. The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2,857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. Constructed atop an older glacially dissected volcano, Shishaldin is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the W and NE sides at 1,500-1,800 m elevation. Shishaldin contains over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, sometimes producing lava flows, have been recorded since the 18th century. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m Based on analysis of satellite imagery, the Darwin VAAC reported that on 8 July ash plumes from Batu Tara rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km W and NW. During 12-14 July, ash plumes rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 25-55 km W, NW, and N. 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 CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m Based on web camera views from the S, SERNAGEOMIN reported that during 3-8 July gas-and-ash plumes rose 1.5 km from Chaitén's growing Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex. Collapses originating from unstable slopes generated block-and-ash flows, particularly in the W area of the complex. The Alert Level remained at Red. Based on web camera views and a SIGMET notice, the Buenos Aires VAAC reported that on 10 July ash plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NE. A thermal anomaly was also seen in satellite imagery on 11 June. Geologic Summary. Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m. Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/, Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m Based on analysis of satellite imagery, the Darwin VAAC reported that on 8 July ash plumes from Dukono rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 85 km NE. Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time. Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m On 10 and 14 July, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.6 km (13,500-15,100 ft) a.s.l. and drifted 10-15 km W and SW. Some explosions were accompanied by rumbling noises and shock waves. Incandescent material was ejected 75 m high and incandescent avalanches descended several ravines. Fumarolic plumes rose 100 m and drifted S and SW. 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. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m During 8-14 July, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha and Kupapa'u ocean entries. Thermal anomalies detected in satellite images and visual observations revealed active surface flows on the pali and on the TEB flow field. Explosions from both ocean entries were reported on 8 July; strong explosions ejected incandescent tephra up to 20 m high at the Waikupanaha entry. The vent in Halema'uma'u crater continued to produce a predominantly white plume that drifted mainly SW. No lava or incandescence from the crater had been seen since a "deflation-inflation" event on 4 July. Small amounts of ash-sized tephra were retrieved from collection bins placed near the plume during the reporting period. The sulfur dioxide emission rate at the summit remained elevated; measurements were between 300 and 400 tonnes per day during 8-10 and 13 July. The 2003-2007 average rate was 140 tonnes per day. 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. Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/ PACAYA Guatemala 14.381°N, 90.601°W; summit elev. 2552 m On 10 and 14 July, INSIVUMEH reported that fumarolic plumes from Pacaya's MacKenney drifted S and gas plumes rose 300 m. Multiple lava flows 150-600 m long traveled SW. Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlan caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (MacKenney cone) grew. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 3-9 July incandescence from Rabaul caldera's Tavurvur cone was visible at night. Steam plumes rose 1.5 km above the crater. Based on analysis of satellite imagery, the Darwin VAAC reported that during 9-10 July ash plumes rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 20-40 km NW, N, and NE. 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. Sources: Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that during 8 and 10-15 July explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. The plumes drifted NE and E. 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 SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that during 3-10 July seismic activity from Shiveluch was above background levels. Based on interpretations of seismic data, ash plumes possibly rose to an altitude of 5.3 km (13,400 ft) a.s.l. on 2 and 4 July, and steam-and-gas plumes with some ash content were emitted during the reporting period. On 3 July, a gas-and-steam plume seen on a video camera rose to an altitude of 3.3 km (10,800 ft) a.s.l. Analysis of satellite imagery revealed a daily thermal anomaly over the lava dome. 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. Intermittent explosive eruptions began in the 1990s 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 +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
