Monday, April 18, 2011

[ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 23-29 March 2011

Smithsonian/USGS Weekly Volcanic Activity Report 23-29 March 2011
From: Sally Kuhn Sennert <>

Smithsonian/USGS Weekly Volcanic Activity Report
23-29 March 2011

Sally Kuhn Sennert - Weekly Report Editor

New Activity/Unrest: | Karangetang [Api Siau], Siau I | Kilauea, Hawaii (USA) | Rabaul, New Britain | San Miguel, El Salvador

Ongoing Activity: | Bagana, Bougainville | Bulusan, Luzon | Karymsky, Eastern Kamchatka (Russia) | Kirishima, Kyushu | Kizimen, Eastern Kamchatka (Russia) | Planchón-Peteroa, Central Chile-Argentina border | Popocatépetl, México | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Tengger Caldera, Eastern Java (Indonesia)

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

KARANGETANG [API SIAU] Siau I 2.78°N, 125.40°E; summit elev. 1784 m

CVGHM reported that during 21-23 March incandescent material from Karangetang was ejected 50-75 m above the crater. Lava flows traveled as far as 2 km and collapses from the lava-flow fronts generated avalanches that moved down the flanks up to 300 m further. On 24 March lava was incandescent in areas 1.5 km away from the crater. Incandescent material from the lava-flow fronts rolled an additional 200-500 m down the flanks. Incandescent material was again ejected 75 m above the crater. Later that day, due to decreased seismicity and a decline in the lava-flow effusion rate, the Alert Level was lowered to 3 (on a scale of 1-4).

Geologic Summary. Karangetang (also known as Api Siau) lies at the northern end of the island of Siau, N of Sulawesi, and contains five summit craters strung along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth-century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars.

Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)

KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m

HVO reported that at Kilauea's east rift zone small areas of incandescence in Pu'u 'O'o crater were visible through the web camera during 23-24 March. The lava lake in the deep pit within Halema'uma'u crater was crusted over; frequent rockfalls produced a few brown-tinged plumes. On 25 March the lava lake reappeared as lava streamed across and eventually covered the floor of the pit. The next day lava returned to Pu'u 'O'o crater about 20 days after the crater floor collapsed on 5 March. Lava slowly filled the deepest parts of the crater forming a lava lake. The lava lake within Halema'uma'u crater again crusted over. During 27-29 March the lava lake in Pu'u 'O'o crater circulated and was fed from two closely-spaced sources in the W center of the lake.

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)

RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m

Based on analyses of satellite imagery, the Darwin VAAC reported that on 29 March an ash plume from Rabaul caldera's Tavurvur cone rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted more than 53 km NW.

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: Darwin Volcanic Ash Advisory Centre (VAAC)

SAN MIGUEL El Salvador 13.434°N, 88.269°W; summit elev. 2130 m

Servicio Nacional de Estudios Territoriales (SNET) reported that during a survey of the San Miguel crater on 9 and 16 March observers noted pulses of gas rising 200 m from the crater. On 12 March the number and amplitude of earthquakes increased. RSAM values rose the next day to 121 units per day on average, up from normal values around 50 units per day. RSAM values continued to fluctuate during the next few days and reached as high as 319 units on 19 March, 414 units on 20 March, and 234 on 21 March. On 18 and 20 March, local residents felt vibrations and heard minor rumbling. Observations on 25 March indicated that gas plumes rose 100 m from the crater. On 28 March SNET noted that seismicity had gradually decreased during the previous few days, and was as low as 80 RSAM units on 27 March. Access to areas within a 2-km-radius remained 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)

Ongoing Activity

BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m

Based on analyses of satellite imagery, the Darwin VAAC reported that during 25-28 March ash plumes from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 35-100 km NW, W, and SW.

Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

BULUSAN Luzon 12.770°N, 124.05°E; summit elev. 1565 m

Based on notices from the Manila airport (RPLL), the Tokyo VAAC reported that during 25-26 March ash from Bulusan was observed. PHIVOLCS reported that cloud cover prevented ground-based observations.

Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed within the 11-km-diameter dacitic Irosin caldera, which was formed more than 36,000 years ago. A broad, flat moat is located below the prominent SW caldera rim; the NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit of Bulusan volcano is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS),
Tokyo Volcanic Ash Advisory Center (VAAC)

KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m

KVERT reported moderate seismic activity at Karymsky during 18-25 March. Seismic data indicated that possible ash plumes rose to an altitude of 3.5 km (11,500 ft) a.s.l. A thermal anomaly was detected in satellite imagery during 19-24 March. The Aviation 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)

KIRISHIMA Kyushu 31.931°N, 130.864°E; summit elev. 1700 m

Based on notifications from JMA, the Tokyo VAAC reported that an eruption from Kirishima's Shinmoe-dake (Shinmoe peak) on 23 March produced a plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE. Subsequent notices that day stated that the ash had dissipated. An eruption on 29 March produced a plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SE.

Geologic Summary. Kirishima is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene volcano group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1,700-m-high Karakuni-dake being the highest. Onami-ike and Mi-ike, the two largest maars, are located SW of Karakuni-dake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Mi-ike to Ohachi, and at Shinmoe-dake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)

KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m

KVERT reported that during 18-25 March seismicity from Kizimen was high, with many shallow volcanic earthquakes and volcanic tremor continuing to be detected. Satellite images showed a large bright thermal anomaly daily on the volcano. Ash and gas-and-steam plumes drifted 313 km N and E during 17 and 19-24 March. The Aviation Color Code remained at Orange. Based on analyses of satellite imagery, the Tokyo VAAC reported that during 25-29 March ash was detected in satellite imagery.

Geologic Summary. Kizimen is an isolated, conical stratovolcano that is morphologically similar to Mount St. Helens prior to its 1980 eruption. The summit of Kizimen consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2,376-m-high Kizimen was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of longterm lava-dome growth have occurred. The latest eruptive cycle began about 3,000 years ago with a large explosion and was followed by lava-dome growth lasting intermittently about 1,000 years. An explosive eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. A single explosive eruption, during 1927-28, has been recorded in historical time.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT),
Tokyo Volcanic Ash Advisory Center (VAAC)

PLANCHON-PETEROA Central Chile-Argentina border 35.240°S, 70.570°W; summit elev. 4107 m

Based on a SIGMET notice, the Buenos Aires VAAC reported ash from an eruption of Planchón-Peteroa on 26 March. Ash was not observed in satellite imagery.

Geologic Summary. Planchón-Peteroa is an elongated complex volcano along the Chile-Argentina border with several overlapping calderas. Activity began in the Pleistocene with construction of the basaltic-andesite to dacitic Volcán Azufre, followed by formation of basaltic and basaltic-andesite Volcán Planchón, 6 km to the N. About 11,500 years ago, much of Azufre and part of Planchón collapsed, forming the massive Río Teno debris avalanche, which reached Chile's Central Valley. Subsequently, Volcán Planchón II was formed. The youngest volcano, andesitic and basaltic-andesite Volcá Peteroa, consists of scattered vents between Azufre and Planchón. Peteroa has been active into historical time and contains a small steaming crater lake. Historical eruptions from the Planchón-Peteroa complex have been dominantly explosive, although lava flows were erupted in 1837 and 1937.

Source: Buenos Aires Volcanic Ash Advisory Center (VAAC)

POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m

Based on information from the Mexico City MWO, analyses of satellite imagery, and web-camera views, the Washington VAAC reported that on 26 March an ash-and-gas plume from Popocatépetl drifted ESE and SE. A subsequent notice that day stated that the ash had dissipated approximately 140 km SE. On 27 March a small ash plume drifted almost 150 m E.

Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.

Source: Washington Volcanic Ash Advisory Center (VAAC)

SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m

Based on information from JMA, the Tokyo VAAC reported that during 23-26 and 29 March explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and occasionally drifted E, SE, and S. On 26 March, a pilot observed an ash plume that rose to an altitude of 3.4 km (11,000 ft) a.s.l. and drifted 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)

SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m

INSIVUMEH reported that on 24 March a loud explosion from Santa María's Santiaguito lava dome complex was followed by a pyroclastic flow that descended the E flank. A few hours later an explosion produced an ash plume that rose 600 m above Caliente dome and drifted W. Based on a METAR notice, information from INSIVUMEH, and analyses of satellite imagery, the Washington VAAC reported a diffuse ash plume on 28 March. Explosions reported by INSIVUMEH during 27-28 March produced ash plumes that rose 300-600 m above the dome and drifted over nearby farms and villages. Block avalanches descended the flanks.

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),
Washington Volcanic Ash Advisory Center (VAAC)

SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m

KVERT reported that during 18-25 March seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 5.8 km (19,000 ft) a.s.l. A thermal anomaly on the lava dome was observed daily in satellite imagery, and ash plumes drifted 373 km SE and N during 18-20 March. Ground-based observers noted that ash plumes rose to an altitude of 6 km (19,700 ft) a.s.l. on 22 March. The Tokyo VAAC reported that on 23 March an eruption detected in satellite imagery and reported by KEMSD produced a plume that rose to an altitude of 6.7 km (22,000 ft) a.s.l. Subsequent notices that day stated that ash then dissipated. The Aviation 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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT),
Tokyo Volcanic Ash Advisory Center (VAAC)

SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m

MVO reported that during 18-25 March activity at the Soufrière Hills lava dome was at a low level. A small lahar occurred in the Belham valley (NW) on 19 March. A relatively large pyroclastic flow traveled likely in excess of 2 km down the Tar River valley to the E and a resulting ash plume drifted W over uninhabited areas. The pyroclastic flow was related to the degradation of the lava dome on the E side as recent observations noted undercutting and overhanging areas on that side. The Hazard Level remained at 3.

Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.

Source: Montserrat Volcano Observatory (MVO)

TENGGER CALDERA Eastern Java (Indonesia) 7.942°S, 112.95°E; summit elev. 2329 m

CVGHM reported that during 22-25 March brownish-gray ash plumes from Tengger Caldera's Bromo cone rose 400-800 m above the crater and drifted SW, NE, and E. Incandescent material was ejected 300 m above the crater, and landed as far as 500 m away during 22-23 March, 300 m away on 24 March, and 250 m away on 25 March. Roaring and booming was also noted. The Alert Level remained at 3 (on a scale of 1-4). Residents and tourists were not permitted within a 2-km-radius of the active crater.

Based on analyses of satellite imagery, the Darwin VAAC reported that during 27-28 March ash plumes rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted 55 km NE.

Geologic Summary. The 16-km-wide Tengger caldera in eastern Java is located at the northern end of a volcanic massif extending from Semeru volcano. The massive Tengger volcanic complex consists of five overlapping stratovolcanoes, each truncated by a caldera. The most recent is the 9 x 10 km wide Sandsea caldera, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most frequently visited and most active volcanoes. More than 50 mild-to-moderate explosive eruptions have occurred since 1804.

Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM),
Darwin Volcanic Ash Advisory Center (VAAC)


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