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SI/USGS Weekly Volcanic Activity Report 28 April-4 May 2010
From: Sally Kuhn Sennert kuhns@xxxxxx
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SI/USGS Weekly Volcanic Activity Report
28 April-4 May 2010
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Eyjafjallajökull, Southern Iceland | Karymsky, Eastern Kamchatka (Russia) | Reventador, Ecuador | Rinjani, Lombok Island (Indonesia) | Santa María, Guatemala | Villarrica, Central Chile
Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Dukono, Halmahera | Gaua, Banks Islands (SW Pacific) | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Suwanose-jima, Ryukyu Islands (Japan)
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
EYJAFJALLAJOKULL Southern Iceland 63.63°N, 19.62°W; summit elev. 1666 m
The Institute of Earth Sciences at the Nordic Volcanological Center (NVC) reported that during 28 April-4 May the eruption from Eyjafjallajökull continued to emit lava and produce steam and ash plumes. Booming sounds in the vicinity of the volcano were often heard. Scientists continued to measure meltwater discharge that flowed down the Gígjökull glacier into the Gígjökull lake basin, then into the Markarfljót River. On 30 April steaming blocks were deposited in the basin, and on 2 May, steam rising from the delta in the lake basin suggested near-boiling water temperatures.
On 28 April the eruption plume was not detected over 4 km altitude (13,100 ft) a.s.l., the level of meteorological clouds. Steam plumes rose above the lava that advanced N down the Gígjöjkull Glacier. Ash plumes rose above the crater; ashfall was seen on the W flanks and in an area about 32 km W. The next day the eruption plume was not visible, but likely did not exceed an altitude of 3.6 km (11,800 ft) a.s.l. Ashfall was reported in areas 1.5 km SW and 12 km SSW.
Steam plumes on 30 April rose to altitude of 4.5-5.1 km (14,800-16,700 ft) a.s.l. Ash plumes rose to lower altitudes, drifted S, and deposited ash in areas 10 km away. Ash plumes rose slightly higher the next day, to an altitude of 5.4 km (17,700 ft) a.s.l. Ashfall was noted in areas 22 km SE. An active lava flow to the N continued to generate steam plumes from interaction with ice.
A report on 2 May stated that during the previous 2-3 days ash plumes had become darker and wider than in the preceding week, explosivity had increased, and tephra fall-out had increased. The location of the steam plume N of the crater indicated that the lava flow had advanced more than 3 km from the crater. Steam and ash plumes continued to rise from the crater. Ashfall was reported in an area 40 km SE. The scoria cone at the crater continued to build. Conditions on 3 May were similar. The largest eruption plume rose to an altitude of 5.5 km (18,000 ft) a.s.l. Ashfall was noted 65-70 km ESE, and ash plumes were seen over the village of Vík, 40 km SE. The eruption plume was seen in satellite imagery as far as 200 km from Eyjafjallajökull on both days.
On 4 May ash plumes rose above the crater and steam plumes rose from the N flank. Lava had traveled 4 km N from the crater, and lava was ejected a few hundred meters from the crater. Ashfall was reported in areas 65-80 km ESE, cutting visibility to less than a few kilometers. An eruption plume was seen in satellite imagery as far as 400 km ESE to SE. According to news articles, airports throughout Ireland were temporarily shut down on 4 May due to ash-plume hazards.
Geologic Summary. Eyjafjallajökull (also known as Eyjafjöll) is located west of Katla volcano. Eyjafjallajökull consists of an E-W-trending, elongated ice-covered basaltic-andesite stratovolcano with a 2.5-km-wide summit caldera. Fissure-fed lava flows occur on both the eastern and western flanks of the volcano, but are more prominent on the western side. Although the 1666-m-high volcano has erupted during historical time, it has been less active than other volcanoes of Iceland's eastern volcanic zone, and relatively few Holocene lava flows are known. An intrusion beneath the south flank from July-December 1999 was accompanied by increased seismic activity and was constrained by tilt measurements, GPS-geodesy and InSAR. The last historical eruption of Eyjafjallajökull prior to an eruption in 2010 produced intermediate-to-silicic tephra from the central caldera during December 1821 to January 1823.
Sources: Institute of Earth Sciences http://www.earthice.hi.is/page/ies_forsida,
Associated Press http://www.cbsnews.com/stories/2010/05/04/world/main6458153.shtml
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that during 23-30 April seismic activity from Karymsky was above background levels, suggesting that possible ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. Volcanologists working in the area on 20 and 21 April saw gas-and-steam plumes containing some ash rise to an altitude of 3 km (10,000 ft) a.s.l. At night, Strombolian activity was occasionally observed. Satellite imagery revealed a daily thermal anomaly over the volcano. The Aviation Color Code level 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/updates.shtml
REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m
The IG reported that on 29 April an explosion from Reventador produced a steam plume with low ash content. Meteorological clouds mostly prevented observations during 30 April-4 May.
Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/
RINJANI Lombok Island (Indonesia) 8.42°S, 116.47°E; summit elev. 3726 m
CVGHM reported that observers at a post located 12.5 km NE of Rinjani saw one whitish-colored plume that rose 100 m from the volcano during February. Dense whitish plumes (and possibly brown) rose 500-900 m in March on 26 occasions and as high as 1,500 m in April on 41 occasions. Plumes seen on 1 and 2 May were "chocolate" in color and rose a maximum height of 1,600 m. From February through April seismicity decreased, although the maximum amplitude of earthquakes increased. CVGHM also noted that ash eruptions and ejected incandescent material fell within Rinjani caldera, but some ash was blown out of the caldera. The Alert Level was raised to 2 (on a scale of 1-4) on 2 May.
Geologic Summary. Rinjani volcano on the island of Lombok rises to 3,726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the E, but the W side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak caldera. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the E end of the caldera. Historical eruptions at Rinjani dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/
SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m
On 30 April, INSIVUMEH reported that explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose to altitudes of 2.8-3.7 km (9,200-12,100 ft) a.s.l. and drifted N and NW. Ashfall was reported in towns downwind. Fumarolic plumes rose 300 m above Caliente dome. A lahar travelled S down the Nima I River, carrying blocks up to 90 cm in diameter. On 4 May an ash plume rose to a maximum altitude of 4 km (13,100 ft) a.s.l.
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.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
VILLARRICA Central Chile 39.42°S, 71.93°W; summit elev. 2847 m
OVDAS-SERNAGEOMIN reported that during February incandescence from Villarrica was seen at night through web cameras. The report reiterated that incandescence was typical; the Alert level remained at Green, Level 1. Video and photographs taken during 24-25 April, and posted on the Projecto Observación Visual Volcán Villarrica (POVI) website, showed Strombolian activity in the crater. Bursts of lava ejected from an unseen source did not rise above the crater rim. Gas plumes rose from the crater.
Geologic Summary. Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km wide caldera formed during the late Pleistocene, more than 0.9 million years ago. A 2-km-wide postglacial caldera is located at the base of the presently active, dominantly basaltic-to-andesitic cone at the NW margin of the Pleistocene caldera. About 25 scoria cones dot Villarrica's flanks. Plinian eruptions and pyroclastic flows have been produced during the Holocene from this dominantly basaltic volcano, but historical eruptions have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Lahars from the glacier-covered volcano have damaged towns on its flanks.
Sources: Observatorio Volcanológico de los Andes del Sur-Servico Nacional de Geología y Minería (OVDAS-SERNAGEOMIN) http://www2.sernageomin.cl/ovdas/ovdas7/ovdas66.php,
Projecto Observación Visual Volcán Villarrica (POVI) http://www.povi.cl/
Ongoing Activity
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 28 and 30 April and during 1-3 May ash plumes from Batu Tara rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted 35-95 km SW, W, and NW.
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
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
The Darwin VAAC reported that on 3 May an ash plume from Dukono was seen on satellite imagery drifting about 90 km W at an altitude of 3 km (10,000 ft) a.s.l.
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 Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
GAUA Banks Islands (SW Pacific) 14.27°S, 167.50°E; summit elev. 797 m
Based on information from the Vanuatu Geohazards Observatory, the Wellington VAAC reported that on 29 April and 2 May ash plumes from Gaua were seen on satellite imagery drifting W and NW at an altitude of 3 km (10,000 ft) a.s.l.
Geologic Summary. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank of Mount Garat in 1962 ended a long period of dormancy.
Source: Wellington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 28 April-4 May HVO reported that activity at Kilauea continued at the summit and the east rift zone. At the summit, episodic rising and falling of the lava-pool surface continued at the deep pit inset within the floor of Halema`uma`u crater; glow from the vent was visible. On most mornings the plume of gas and ash from the summit vent drifted NW, W, and SW. On 29 April small rockfalls disrupted the surface of the pond, producing "dusty" plumes. Sulfur dioxide emission rates measured at the summit during 28-29 April were in the 800-1,000 tonnes/day range.
At the east rift zone, lava flowed through tubes to supply a surface flow that had advanced down the Pulama pali, onto the coastal plain, heading S, and reached the ocean on 29 April. Lava continued to flow into the ocean, just W of the "old" coastal viewing area during the rest of the reporting period. Lava also flowed along the E margin, between the highway and the coast. Incandescence was sometimes seen from a vent low on the S wall of Pu'u 'O'o crater.
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/
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 22-30 April seismic activity from Kliuchevskoi was above background levels. Strombolian activity was noted and lava continued to flow down the flanks. Gas-and-steam plumes containing small amounts of ash were seen on 22 April. Similar plumes rose to an altitude of 7.3 km (23,900 ft) a.s.l. during 25-27 April, and drifted W and SW. Satellite imagery revealed a large daily thermal anomaly from the volcano. An ash plume drifted about 65 km W on 24 April, and gas-and-steam plumes drifted 55 km W and SW during 24-27 April. Based on analyses of satellite imagery, the Tokyo VAAC reported that on 3 May a possible eruption produced a plume that rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted W. The Aviation Color Code level remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/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 28 April-5 May explosions from Sakura-jima often produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and sometimes drifted NE, E, and SE.
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 23-30 April seismic activity from Shiveluch was above background levels and suggested that possible ash plumes rose to an altitude of 5.7 km (18,700 ft) a.s.l. During 22-25 April ash plumes from hot avalanches rose to an altitude of 3 km (10,000 ft) a.s.l. and fumarolic activity from the lava dome was noted. Satellite imagery revealed a large daily thermal anomaly from the lava dome, and ash plumes that drifted about 60 km SE on 28 April. The Aviation Color Code level 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/updates.shtml
SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m
Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose-jima on 29 April, and during 1 and 4-5 May. Details of possible resulting plumes were not reported.
Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent Strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for about 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
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