******************************************************************************************** Smithsonian/USGS Weekly Volcanic Activity Report 17-23 August 2011 From: "Kuhn, Sally" <KUHNS@xxxxxx> ******************************************************************************************** New Activity/Unrest: | Bagana, Bougainville | Cleveland, Chuginadak Island | Etna, Sicily (Italy) | Kilauea, Hawaii (USA) | Manam, Northeast of New Guinea (SW Pacific) | Rabaul, New Britain Ongoing Activity: | Dukono, Halmahera | Karymsky, Eastern Kamchatka (Russia) | Kizimen, Eastern Kamchatka (Russia) | Puyehue-Cordón Caulle, Central Chile | Sakura-jima, Kyushu | San Cristóbal, Nicaragua | 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 BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 21 August an ash plume from Bagana rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 93 km 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) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m AVO reported that during 17-23 August cloud cover over Cleveland prevented observations of the summit crater. On 21 August AVO noted that a weak, 1-pixel thermal anomaly was observed in a recent satellite view during a cloud break. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange. No current seismic information was available because Cleveland does not have a real-time seismic network. 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 eight days after the preceding episode, Etna's New SE Crater was the site of another paroxysmal eruptive episode on the morning of 20 August, the eleventh event of this type since the beginning of 2011. The event began on 18 August with increased gas emissions from New SE Crater. On 19 August a powerful explosion ejected incandescent bombs and produced a small ash plume. The event was followed by a few more minor explosions, all accompanied by an increase in volcanic tremor amplitude and focal shift from the NE Crater toward the New SE Crater. Throughout the day small dilute ash was emitted. During the evening weak Strombolian activity commenced, with small explosions occurring about every 30 minutes. On 20 August weak but continuous incandescence due to lava emissions appeared in the crater. Strombolian activity intensified, and lava overflowed the rim through a breach in the E crater rim traveling towards the Valle del Bove. Almost five hours later lava fountaining generated heavy fallout of large pyroclastics onto the flanks of the cone. Dense plumes of gas and tephra rose 5-6 km from the crater and drifted SW, causing ash- and lapilli-fall in areas such as Paternò (22 km SSW), Ragalna (13 km SSW), and Biancavilla (16 km SW). Closer to the crater, in the Torre del Filosofo area to the S, clasts up to several tens of centimeters in diameter landed on the ground. Light brown dust clouds appeared in an area on the lower E flank of the cone, where a small depression had formed a few hours after the 12 August event. Shortly thereafter, the continuous, intense ejection of pyroclastics onto the flanks of the cone generated avalanches resembling pyroclastic flows, which descended a few hundred meters beyond the base of the cone, mainly towards the S. In the meantime, the lower portion of the E flank of the cone began to slide and collapse under the push of lava from within the channel. A new lava flow issued from the collapsed area, taking a more southerly path than the lava emitted until then, and divided into numerous branches. Lava fountaining slowed later in the evening and eventually ceased, followed by ash emissions from the crater for a few minutes. A series of ash explosions lasted for five minutes in the early morning on 21 August. The morphological changes affecting the pyroclastic cone surrounding the New SE Crater were significant. Besides the collapse on the lower E flank of the cone, the S and NE rims of the cone had grown in height. 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/ KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m During 17-23 August, HVO reported that lava continued to trickle onto the collapsed floor of Kilauea's Pu'u 'O'o' crater and some spattering occurred from various areas on the floor. The only activity on the W flank was observed during 17-20 August; a small lava flow from the base of the N pond rim near the Kamoamoa fissures and a larger flow from the N flow branch were both active. During 20-21 August a small amount of lava emitted from a vent on the S crater floor flowed a short distance. Later, lava started issued in larger quantities from another source on the S part of the floor that quickly filled in a low trench. Lava continued to flow onto the crater floor during the next two days. During 17-18 August lava flowed onto the floor of the vent inset within the E wall of Halema'uma'u Crater. By the next day a persistent spattering source at the W edge of the cavity pushed the lava surface sluggishly from W to E. During 19-21 August drain-and-fill cycles were observed; the highest level of the lava surface was below the inner ledge 75 m below Halema'uma'u Crater floor. 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/ MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m RVO reported that the summit area of Manam was obscured by atmospheric clouds on most days during 1-19 August. When the summit was clear to viewers on the mainland, 15-20 km away from Manam, both vents were emitting white vapor plumes. Main Crater produced light-gray ash clouds during 13 and 17-18 August, and bright, steady incandescence was visible on most clear nights. Weak incandescence was visible from Southern Crater on some nights. People living on the island reported occasional noises from both craters on 3 and 11 August. Seismicity during the reporting period was dominated by volcanic tremors. Discrete high-frequency volcano-tectonic earthquakes were also recorded. RVO noted that high-frequency volcano-tectonic earthquakes are not very common for Manam. An electronic tiltmeter located about 4 km SW from the summit craters continued to show inflation towards the summit area. Based on analysis of satellite imagery, the Darwin VAAC reported that during 18-21 August ash plumes rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted 45-90 km NW and W. Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas. Sources: Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m RVO reported that white vapor plumes rose from Rabaul caldera's Tavurvur cone during 15-19 August. No volcano-related seismicity was recorded. The rate of uplift from GPS measurements on Matupit Island had increased from the end of July. 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) Ongoing Activity DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m Based on analyses of satellite imagery, the Darwin VAAC reported that during 18-21 August ash plumes from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 110-150 km NE and N. 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 KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that during 12-19 August moderate seismic activity continued at Karymsky, indicating that possible ash plumes rose to an altitude of 4.2 km (13,800 ft) a.s.l. A thermal anomaly on the volcano was detected by satellite during 14 and 17-18 August; cloud cover prevented observations on the other days. 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) http://www.kscnet.ru/ivs/kvert/index_eng.php KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m KVERT reported that during 12-19 August seismicity from Kizimen was above background levels and weak volcanic tremor continued to be detected. Video images showed an occasional steam plume that rose to an altitude of 3 km (9,800 ft) a.s.l. and fumarolic activity on 14 August. A lava flow on the E flank was active. Satellite images showed a large bright thermal anomaly on the volcano all week and a gas-and-steam plume that drifted 57 km NNE on 15 August. The Aviation Color Code remained at Orange. Based on analyses of satellite imagery, the Tokyo VAAC reported that a possible eruption on 20 August produced a plume that rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted E. Subsequent images that day showed that continuing ash emissions had later dissipated. 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) 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 PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m During 16-23 August, OVDAS-SERNAGEOMIN reported that seismic activity indicated the eruption from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, continued at a low level. Cloudy weather mostly prevented satellite and camera observations of the eruption during 16-17 August, however a mostly white plume was observed by an area camera rising 2 km above the crater on 16 August. A plume that was sometimes gray rose 2.5 km above the crater on 18 August. A plume observed in satellite imagery that same day drifted 200 km NW. A period of harmonic tremor that lasted about 25 minutes may have indicated lava emission. Incandescence was observed at night during 18-19 August. On 19 August a camera recorded a mostly white plume that rose 2 km above the crater. Satellite imagery showed a plume drifting 270 km NW. During an overflight, conducted by ONEMI in collaboration with the Air Force, scientists observed a white plume rising 1.4 km that was dark gray for the first few meters above the vent. Solidified lava filled up a depression around Cordón Caulle; no active lava flows were noted. On 20 August a plume that was mostly white rose 2.5 km above the crater. Two explosive events caused the plume to rise 4 km and contain a higher concentration of ash. Satellite imagery showed a plume drifting 200 km WNW on 20 August, and 500 km SE and NW on 21 August. A white plume that rose 2 km above the crater was observed on 22 August. Satellite imagery showed a very diffuse plume drifting E. 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 17-22 August explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted E. On 18 August, a pilot observed an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. 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 SAN CRISTOBAL Nicaragua 12.702°N, 87.004°W; summit elev. 1745 m The Washington VAAC reported that on 21 August emissions of gas and light ash from San Cristóbal were possibly detected in satellite imagery drifting 35 km WNW. Ash was not detected in subsequent images. Geologic Summary. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1,745-m-high youngest cone, San Cristóbal itself (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristóbal, are of Pleistocene age. Volcán Casita contains an elongated summit crater and lies immediately E of San Cristóbal; Casita was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that seismic activity at Shiveluch was moderate during 12-19 August, and indicated that possible ash plumes rose to an altitude of 6.8 km (22,300 ft) a.s.l. on 13 August and to an altitude of 7.8 km (25,600 ft) a.s.l. on 15 August. Ash plumes may have risen to an altitude of 5 km (16,400 ft) a.s.l. on the other days. Gas-and-steam plumes containing ash observed in satellite imagery drifted 30 km SW on 12 August. Ground-based observers noted that an ash plume rose to an altitude of 6.5 km (21,300 ft) a.s.l. on 16 August. 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. 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@xxxxxxx. To contribute to the volcano list, send your message to: volcano@xxxxxxx. Please do not send attachments. ==============================================================
