******************************************************************************************** Smithsonian/USGS Weekly Volcanic Activity Report 27 July-2 August 2011 From: "Kuhn, Sally" <KUHNS@xxxxxx> ******************************************************************************************** Smithsonian/USGS Weekly Volcanic Activity Report 27 July-2 August 2011 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Cleveland, Chuginadak Island | Etna, Sicily (Italy) | Marapi, Sumatra (Indonesia) | Poás, Costa Rica | Rabaul, New Britain | Stromboli, Aeolian Islands (Italy) Ongoing Activity: | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Puyehue-Cordón Caulle, Central Chile | 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 CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m AVO reported that on 2 August the Volcano Alert Level for Cleveland was raised to Watch and the Aviation Color Code was raised to Orange due to the formation of a 40-m-wide lava dome in the summit crater that was observed on 29 July. The lava dome was extruded sometime after 7 July following the last clear view of the summit area, however thermal anomalies observed since 19 July suggested that the dome had extruded since that time. Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m Sezione di Catania - Osservatorio Etneo reported that in the evening of 28 July Strombolian explosions from the active vent on the E flank of Etna's SE Crater cone were weak and sporadic, then ceased during the night. Throughout 29 July the crater was quiet. In the early morning of 30 July intermittent incandescence from the crater gradually intensified and became more frequent, then was followed by intense Strombolian activity accompanied by loud detonations. Lava bombs ejected several tens of meters fell back into the crater or around the rim. A diffuse ash plume drifted E. A small lava flow on the E flank descended about 100 m then rapidly chilled. The activity was accompanied by a distinct increase in the mean amplitude of volcanic tremor that, along with the activity, abruptly decreased in the early afternoon. Later that day the mean amplitude of volcanic tremor increased again along with Strombolian activity. A diffuse gas-and-ash plume again drifted E. Strombolian activity intensified and incandescent jets became continuous. At the same time lava flowed E and the effusion rate rapidly increased; lava flowed 3 km down the W slope of the Valle del Bove. The ash plume became more dense and ashfall was reported in the Ionian area (18 km E). During the most intense period, fragments of fluid lava were ejected 450-500 m above the crater and fell onto the flanks of the pyroclastic cone to distances of 200-300 m. Lava fountains jetted from at least two vents located within the crater and on the upper E flank, roughly aligned WNW and ESE. The activity ceased just after midnight. The event on 30 July was the eighth paroxysmal event in 2011. Geologic Summary. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna's summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania. Source: Sezione di Catania - Osservatorio Etneo http://www.ct.ingv.it/ MARAPI Sumatra (Indonesia) 0.381°S, 100.473°E; summit elev. 2891 m CVGHM reported increased seismicity from Marapi during 21 June-3 August. Observers noted that during June and July white plumes rose 15-75 m above the summit craters. On 1 August white plumes rose 15 m above the main crater; fog prevented observations the next day. On 3 August dense gray plumes rose 300-1,000 m above the crater on eight occasions. That same day CVGHM raised the Alert Level to 2 (on a scale of 1-4). Visitors and residents were prohibited from going within a 3-km radius of the summit. Geologic Summary. Gunung Marapi, not to be confused with the better known Merapi volcano on Java, is Sumatra's most active volcano. Marapi is a massive complex stratovolcano that rises 2,000 m above the Bukittinggi plain in Sumatra's Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, along which volcanism has migrated to the W. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no historical lava flows outside the summit craters have been reported. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/ POAS Costa Rica 10.20°N, 84.233°W; summit elev. 2708 m OVSICORI-UNA reported that on 23 July a group of observatory scientists visited Poás to document changes that had occurred there during the previous weeks. They noted that the subtle, semicircular scarp observed a few months earlier had rapidly progressed to a sharp scarp on the SE shore of Laguna Caliente. The 60-m-wide, 2.5-m-high scarp degassed and geyser activity was observed on the W end, next to the steaming lake. In an area about 40 m above the surface of the lake where there were fractured rocks and vigorous gas venting, incandescence emanated from the lava dome and a temperature of 670 degrees Celsius was measured. Geologic Summary. The broad, well-vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano, which is one of Costa Rica's most prominent natural landmarks, are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the 2,708-m-high complex stratovolcano extends to the lower northern flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, is cold and clear and last erupted about 7,500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since the first historical eruption was reported in 1828. Poás eruptions often include geyser-like ejection of crater-lake water. Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/ RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m RVO reported that white vapor occasionally tinted blue rose from Rabaul caldera's Tavurvur cone during 1-28 July. Dull incandescence emanated from a small caved-in vent on the floor of the crater. The start of an ash eruption on 29 July was marked by an emergent low-frequency tremor and slowly rising gray ash plumes. One explosion on 30 July possibly produced light ashfall to the NW. Seismic data indicated forceful degassing on 1 August. 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: Rabaul Volcano Observatory (RVO) STROMBOLI Aeolian Islands (Italy) 38.789°N, 15.213°E; summit elev. 924 m Sezione di Catania - Osservatorio Etneo reported that during the late evening of 1 August a vast accumulation of incandescent material appeared at the base of Stromboli's N1 vent, the northernmost active vent within the crater terrace at about 750 m elevation. Within a few minutes, the material collapsed and slid downslope, creating two small lobes of lava. The more easterly flow descended the N slope of the Sciara del Fuoco, generating small landslides from the loose material on the slope, and marking the first lava effusion event outside of the crater since a small emission during 11-12 December 2010. The lava accumulated on a flat area near hornitos that were formed during 2002-2003, before continuing further down a steep slope. On 2 August the lava had descended to 500 m elevation and advanced very slowly. During the afternoon effusion appeared to have diminished. Geologic Summary. Spectacular incandescent nighttime explosions at Stromboli volcano have long attracted visitors to the "Lighthouse of the Mediterranean."Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout historical time. The small, 926-m-high island of Stromboli is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The active summit vents are located at the head of the Sciara del Fuoco, a horseshoe-shaped scarp formed as a result of slope failure that extends to below sea level and funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded at Stromboli since Roman times. Source: Sezione di Catania - Osservatorio Etneo http://www.ct.ingv.it/ Ongoing Activity KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that during 22-29 July moderate seismic activity continued at Karymsky and possible ash plumes rose from the crater. A thermal anomaly on the volcano was detected by satellite during 22 and 24-27 July; cloud cover prevented observations on the other days. The Aviation Color Code remained at Orange. Based on information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 30 July an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SW. 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. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m HVO reported that two lava lakes at Kilauea were active during 27 July-2 August. The level of the summit lava lake fluctuated deep in the 150-m-diameter vent inset within the E wall of Halema'uma'u Crater and circulated with various patterns. Periodic measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and occasionally fresh spatter nearby. Lava from the Puka Nui and MLK pits, smaller craters to the W of the main Pu'u 'O'o crater, continued to overflow to the SW, producing a tube-fed pahoehoe flow that had advanced about 700 m from the Puka Nui rim during 25-30 July. Lava from the base of the NE crater filled a trough between the crater wall and the perched lava lake. Uplift of the crater floor and lava lake continued until 30 July, when a breakout lava flow started along the base of the crater's S wall and the lake slowly subsided. Subsidence continued the next day but switched to inflation on 1 August. The preliminary sulfur dioxide emission rate from all east rift zone sources was calculated at 1,700, 1,000, and 800 tonnes/day on 29 and 30 July, and 1 August, respectively. 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/ KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m KVERT reported that photos taken of Kizimen on 20 July showed that the lava flow on the E flank, which began in January, remained active. During 22-29 July seismicity was above background levels and weak volcanic tremor continued to be detected. Satellite images showed a bright thermal anomaly on the volcano all week and seismic data indicated that possible ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. Seismologists in the area observed the active lava flow on the E flank. The Aviation Color Code remained at Orange. 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m During 25 July-1 August, OVDAS-SERNAGEOMIN reported that the eruption from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, continued and seismicity indicated that the lava flow remained active. Cloud cover prevented observations by a video camera on 25 July, though satellite imagery detected a plume that drifted 200 km SE. On 26 July the camera recorded a plume that rose 2 km above the crater and incandescence up to 500 m above the crater was observed at night. Satellite imagery showed a plume drifting 100 km SE. Cloud cover again prevented camera observations during 27-28 July, but on 28 July a 150-km-long plume was observed in satellite imagery drifting SE. During 29-31 July plumes rose 2-5 km above the crater and satellite imagery showed plumes drifting 80-400 km SW, N, and NE. Incandescence was observed up to 300 m above the crater at night during 29-30 July. Cloud cover prevented observations on 1 August. The Alert Level remained at Red. Geologic Summary. The Puyehue-Cordón Caulle volcanic complex (PCCVC) is a large NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end by the Cordón Caulle fissure complex. The Pleistocene Mencheca volcano with Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue volcano is the most geochemically diverse of the PCCVC. The flat-topped, 2236-m-high Puyehue volcano was constructed above a 5-km-wide caldera and is capped by a 2.4-km-wide summit caldera of Holocene age. Lava flows and domes of mostly rhyolitic composition are found on the eastern flank of Puyehue. Historical eruptions originally attributed to Puyehue, including major eruptions in 1921-22 and 1960, are now known to be from the Cordón Caulle rift zone. The Cordón Caulle geothermal area, occupying a 6 x 13 km wide volcano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/ SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that during 27 July-2 August plumes from Sakura-jima rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. During 28-30 July and 1 August, pilots observed ash plumes that rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. Plumes occasionally drifted SW, S, SE, and W. 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 seismic activity at Shiveluch was moderate during 22-29 July and indicated that possible ash plumes rose to an altitude of 4.7 km (15,400 ft) a.s.l. during 23 and 25-27 July. Satellite imagery showed a thermal anomaly on the lava dome on 22 July; cloud cover prevented observations on other days. Ground-based observers noted fumarolic activity on 24 July. The Aviation Color Code remained at Orange. Based on information from KEMSD, the Tokyo VAAC reported that on 1 August an eruption produced a plume that rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted E. Ash was seen in subsequent satellite images that same day. 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) http://www.kscnet.ru/ivs/kvert/index_eng.php, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/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@xxxxxxx. To contribute to the volcano list, send your message to: volcano@xxxxxxx. Please do not send attachments. ==============================================================
