****************************************** GVP/USGS Weekly Volcanic Activity Report 27 December 2006-2 January 2007 http://www.volcano.si.edu/ ****************************************** New Activity/Unrest: | Bezymianny <http://www.volcano.si.edu/reports/usgs/#bezymian> , Russia | Shiveluch, Russia | Soufrière Hills <http://www.volcano.si.edu/reports/usgs/#soufhill> , Montserrat Ongoing Activity: | Karymsky <http://www.volcano.si.edu/reports/usgs/#karymsky> , Russia | Kilauea <http://www.volcano.si.edu/reports/usgs/#kilauea> , USA | Rabaul <http://www.volcano.si.edu/reports/usgs/index.cfm#rabaul> , Papua New Guinea | Sakura-jima <http://www.volcano.si.edu/reports/usgs/index.cfm#sakura> , Japan | Sangay <http://www.volcano.si.edu/reports/usgs/#sangay> , Ecuador | Santa María, Guatemala | Tungurahua <http://www.volcano.si.edu/reports/usgs/#tungurah> , Ecuador | Ubinas <http://www.volcano.si.edu/reports/usgs/#ubinas> , Perú New Activity/Unrest BEZYMIANNY Kamchatka Peninsula, Russia 55.98°N, 160.59°E; summit elev. 2,882 m Based on aerial observations, KVERT reported on 29 December that part of Bezymianny's lava dome was destroyed during explosive activity on 24 December. Moderate fumarolic activity was observed during 26-27 December and seismic activity was at background levels during 26-29 December. The level of Concern Color Code was lowered to Yellow <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. The modern Bezymianny volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral volcano that was built between about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of Mount St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater. Source: Kamchatkan Volcanic Eruption Response Team http://www.kscnet.ru/ivs/kvert/updates.shtml Bezymianny Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-25= SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m KVERT reported that seismic activity from Shiveluch decreased on 27 December, but still remained above background levels. Based on video data, a steam-and- gas plume rose to 3.5 km (11,500 ft) a.s.l. on 27 December. On 28 December, ash plumes rose to 10 km (32,800 ft) a.s.l. and were seen on satellite imagery drifting E. The level of Concern Color Code was lowered to Orange <http://www.avo.alaska.edu/color_codes.php>. Based on information from the Kamchatkan Experimental & Methodical Seismological Department (KEMSD) and satellite imagery, the Tokyo VAAC reported that eruptions produced plumes rising to 4.9-8.2 km (16,000-27,000 ft) a.s.l. on 1 and 2 January. 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 <http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> within a large horseshoe-shaped caldera formed by collapse of the massive late-Pleistocene <http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic <http://volcanoes.usgs.gov/Products/Pglossary/andesite.html> volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome <http://volcanoes.usgs.gov/Products/Pglossary/LavaDome.html> complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. During the 1990s, intermittent explosive eruptions took place 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 http://www.kscnet.ru/ivs/kvert/updates.shtml, Tokyo Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Shiveluch Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1000-27= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m During 22-29 December, the rate of lava-dome growth at Soufrière Hills increased and was focused on the W, where gas-and-ash venting occurred. A high whaleback lobe directed towards the SW was observed on 26 December. On 28 December, a small pyroclastic flow traveled W toward Gages valley. The Washington VAAC reported on-going steam and ash emissions that were visible on satellite imagery during 27 December-2 January. 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 east, was formed during an eruption about 4000 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. Sources: Montserrat Volcano Observatory http://www.mvo.ms/, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Soufrière Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= Ongoing Activity KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Activity at Karymsky continued during 27 December-2 January, with 100-130 shallow earthquakes occurring daily. Ash plumes may have reached altitudes of 2 km (6,600 ft) a.s.l. A thermal anomaly in the crater was detected during 21-22 December. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. 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 http://www.kscnet.ru/ivs/kvert/updates.shtml Karymsky Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13= KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m During 27 December-2 January, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae'apuki and East Ka'ili'ili entries. Between those two entries, lava streams were visible on 27 and 28 December descending to the ocean to re-establish the Kamokuna entry. Incandescence was intermittently visible on the pali and from the East Pond and January vents, South Wall complex, and Drainhole vent in Pu'u 'O'o's crater. Tremor near Pu`u `O`o continued at low levels. 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 by lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. The latest Kilauea eruption began in January 1983 along the E rift zone. This long-term ongoing eruption from Pu`u `O`o-Kupaianaha has produced lava flows that have traveled 11-12 km from the vents to the sea, paving broad areas on the S flank of Kilauea and adding new land beyond the former coastline. Source: US Geological Survey Hawaiian Volcano Observatory http://volcano.wr.usgs.gov/hvostatus.php Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 24-29 December Rabaul caldera's Tavurvur cone emitted ash plumes that rose to 1.1-3.7 km (3,600-12,000 ft) a.s.l. and drifted in multiple directions. Ashfall was reported from areas downwind including Rabaul town on 25, 27, and 28 December. 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: Herman Patia, Rabaul Volcano Observatory Rabaul Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m Based on information from Japan Meteorological Agency (JMA), the Tokyo VAAC reported an eruption from Sakura-jima on 2 January. The resultant plume reached an altitude of 3.4 km (11,000 ft) a.s.l. and drifted SW. 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 http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Sakura-jima Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08= SANGAY Ecuador 2.03°S, 78.34°W; summit elev. 5,188 m Based on information from Guayaquil Meteorological Watch Office (MWO) and satellite imagery, the Washington VAAC reported that an eruption from Sangay on 1 January produced an ash plume that rose to an altitude of 5.2 km (17,000 ft) a.s.l. Geologic Summary. The isolated Sangay volcano, located E of the Andean crest, is the southernmost of Ecuador's volcanoes, and its most active. It has been in frequent eruption for the past several centuries. The steep-sided, 5,230-m-high glacier-covered volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the E, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. Sangay towers above the tropical jungle on the E side; on the other sides flat plains of ash from the volcano have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The more or less constant eruptive activity has caused frequent changes to the morphology of the summit crater complex. Source: Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Sangay Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-09= SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m INSIVUMEH reported that on 28 December a series of small sector collapses from the SW edge of Santa María's Caliente dome produced pyroclastic flows that traveled about 2 km down a ravine. On 29 December, another collapse produced pyroclastic flows and incandescent blocks. Thick ash plumes associated with the pyroclastic flows on both days reached an altitude of 4.3 km (14,000 ft) a.s.l. and drifted W and NW. According to the Washington VAAC, minor emissions of gas and possible ash were visible on satellite imagery on 1 and 2 January. The narrow ash plumes drifted WSW. 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 http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Santa María Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-03= TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m During 27 December-2 January, seismicity at Tungurahua remained moderate to low and visual observations were limited due to inclement weather. On 27 and 28 December, lahars traveled down drainages including Bilbao to the W, Mandur to the NNW, and Mapayacu to the SW. Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have been restricted to the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano. Source: Instituto Geofísico-Escuela Poltécnica Nacional http://www.igepn.edu.ec/ Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m Based on pilot reports, the Buenos Aires VAAC reported continuous emissions from Ubinas on 27 and 30 December. Ash plumes rose to 4.9-8.5 km (16,000-28,000 ft) a.s.l. and drifted E. Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02 ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
