GVP/USGS Weekly Volcanic Activity Report 16-22 May 2007 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Bezymianny, Russia | Bulusan, Philippines | Kliuchevskoi, Russia | Ritter Island, Papua New Guinea Ongoing Activity: | Bagana, Papua New Guinea | Home Reef, Tonga | Karymsky, Russia | Kilauea, USA | Reventador, Ecuador | Sakura-jima, Japan | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest BEZYMIANNY Kamchatka Peninsula, Russia 55.98°N, 160.59°E; summit elev. 2,882 m KVERT reported on 17 May that the Level of Concern Color Code <http://www.avo.alaska.edu/ color_codes.php> for Bezymianny was lowered to Yellow. Satellite imagery showed that the thermal anomaly decreased in size during 15-17 May. Hunters reported that a large mudflow, 200 m in width, moved along the Sukhaya Khapitsa river on 17 May. 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 (KVERT) 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= BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m PHIVOLCS reported on 20 May that seismicity from Bulusan remained high following the explosion on 12 May. Ground deformation measurements conducted on 17 May on the NE flank revealed 4 mm of inflation compared to the previous measurement on 7 April. The Alert Level was raised from 1 to 2 (out of 5) due to the increased seismicity and inflation. 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. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http:// www.phivolcs.dost.gov.ph/ Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= KLIUCHEVSKOI Kamchatka Peninsula, Russia 56.06°N, 160.64°E; summit elev. 4,835 m KVERT reported that during 11-22 May, seismic activity at Kliuchevskoi continued above background levels and a thermal anomaly in the crater was detected on satellite imagery. According to video data and visual observations, Vulcanian activity at the terminal crater and phreatic bursts at the NW flank of the volcano were observed on 11 and 16 May. Also on 11 and 16 May, ash plumes rose to 9.7 km (31,800 ft) a.s.l. and drifted E and NE, respectively. Clouds inhibited observation on other days. Ashfall was reported from the town of Klyuchi, about 30 km to the NE, during 11-12 and 16-17 May. KVERT raised the Level of Concern Color Code <http://www.avo.alaska.edu/color_codes.php> from Orange to Red on 17 May. On 18 May, KVERT reported that deposits from a mudflow filled the Krivaya river. During 18-22 May, ash plumes rose to an altitude of 8.5 km (27,900 ft) a.s.l. Based on observations from satellite imagery, ash plumes drifted N, NE, NW, and E during 11-22 May. 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 have occurred during the past 3,000 years, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation. 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 eruptions from flank craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/ updates.shtml Kliuchevskoi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-26= RITTER ISLAND Papua New Guinea 5.52°S, 148.121°E; summit elev. 140 m According to a news article, "sea surges" destroyed four homes and a boat following an eruption of Ritter Island on 19 May. About 1,500-2,000 people on Siassi Island moved to higher ground. Villagers reported seeing plumes from the island, hearing rumbling noises, and feeling earthquakes. The article also mentioned that RVO and the Geophysical Observatory in Port Moresby did not record any seismic activity from the eruption. Geologic Summary. Prior to 1888, Ritter Island was a steep-sided nearly circular island about 780-m high. Several historical explosive eruptions had been recorded prior to 1888, when large-scale slope failure destroyed the summit of the conical volcano, leaving an arcuate 140-m-high island remnant with a steep W-facing scarp. Devastating tsunamis were produced by the collapse and swept the coast of Papua New Guinea and offshore islands. Two minor post-collapse explosive eruptions, during 1972 and 1974, occurred offshore within the largely submarine 3.5 x 4.5 km breached depression formed by the collapse. Source: Australian Associated Press http://www.news.com.au/adelaidenow/story/ 0,22606,21774791-912,00.html?from=public_rss Ritter Island Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-07= Ongoing Activity BAGANA Bougainville Island, Papua New Guinea 6.14°S, 155.19°E; summit elev. 1,750 m RVO reported that white vapor emissions from Bagana's summit crater continued during 10 March-20 May. Emissions were occasionally forceful, and were accompanied by ash clouds during 17 March, 1 April, and 3-5 April. Weak roaring noises were heard on 4 April. Summit incandescence was visible on 20 and 24 March and 17 May. Based on satellite imagery and information from RVO, the Darwin VAAC reported that a diffuse plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted SW on 20 May. RVO reported that forceful, white emissions on 21 May produced plumes to an altitude of 2.3 km (8,200 ft) a.s.l. and drifted W. 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. Sources: Herman Patia, Rabaul Volcano Observatory, Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Bagana Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0505-02= HOME REEF Tonga Islands, Tonga 18.992°S, 174.775°W; summit elev. -2 m Pumice from the Home Reef eruption that began early-to-mid August 2006 reached the eastern Australian coast in March 2007. A substantial stranding of the pumice in mid-April extended for more than 1,300 km along the Queensland and northern New South Wales coast. Pumice clasts ranged in size from 1-4 cm in diameter, with the largest clasts up to 17 cm in diameter. A visit to the area in February 2007 revealed a pumice mound barely visible over the waves. Geologic Summary. Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, copious amounts of floating pumice, and an ephemeral island 500 x 1500 m wide, with cliffs 30-50 m high that enclosed a water-filled crater. Source: Scott Bryan, School of Earth Sciences and Geography, Kingston University Home Reef Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0403-08= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Seismic activity at Karymsky was slightly above background levels during 11-18 May. On 13 May, a possible ash plume rose to an altitude of 1.7 km (5,600 ft) a.s.l. 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 (KVERT) 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 16-22 May, lava from Kilauea continued to flow SE across a lava delta into the ocean at the Kamokuna entry. On 16 May, lava from the E arm of the Campout flow advancing along the coastal plain from the base of the Royal Gardens sub-division, reached the ocean at the newly-formed Poupou entry. On 18 May, field crews reported that the Poupou entry, about 1.6 km E of the Kamokuna entry, was 20 m wide and building a delta. Incandescence was visible from several vents in the Pu'u 'O'o crater and from breakouts on, above, and at the base of the Pulama pali fault scarp. Earthquake activity that initially increased on 12 May was scattered beneath the upper rift zone and S-flank areas. According to a news article, new measurements revealed that the area of the 10 May bench collapse at East Lae'apuki lava delta was about 9.3 hectares (23 acres). Scientists reported that new cracks in the lava delta were observed within several hundred yards of the ocean's edge. 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- REVENTADOR Ecuador 0.078°S, 77.656°W, summit elev. 3,562 m On 16 May, IG reported that a steam plume from Reventador rose to an altitude of 3.6 km (11,900 ft) a.s.l. and drifted to the NW. The plume was visible on satellite imagery. On 18 May, strong rains resulted in a lahar that lasted approximately 40 minutes. A lahar was also noted on 22 May. Visual observations were hindered during most of the reporting period due to inclement weather. 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 http://www.igepn.edu.ec/ Reventador Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-01= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m Based on information from JMA and a pilot report, the Tokyo VAAC reported that ash plumes from Sakura-jima rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. during 16 and 20-22 May. Plumes drifted NW on 16 May and rose straight up during 20-22 May. 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 Sakura-jima Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08= SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m KVERT reported that seismic activity at Shiveluch continued above background levels during 11-18 May. Based on seismic interpretation, ash plumes possibly rose to an altitude of 6 km (19,700 ft) a.s.l. throughout the reporting period. A large thermal anomaly was visible on satellite imagery. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. 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 horseshoe-shaped 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. 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/ updates.shtml 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 Based on visual observations, MVO reported that during 11-21 May lava-dome growth at Soufrière Hills likely ceased and the overall structure of the dome changed very little. Low-level rockfall and pyroclastic flow activity continued. Seismic activity was very low. The Alert Level remained at 4 (on a scale of 0-5). 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. Source: Montserrat Volcano Observatory http://www.mvo.ms/ Soufrière Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m Data from deformation-monitoring instruments indicated that during 16-22 May lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. In some instances, clouds inhibited visual observations. Geologic Summary. Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago, and has been the most active volcano in the Cascade Range during the Holocene. The modern edifice was constructed during the last 2,200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the N flank, and were witnessed by early settlers. Source: US Geological Survey Cascades Volcano Observatory http://vulcan.wr.usgs.gov/Volcanoes/ MSH/CurrentActivity/framework.html St. Helens Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1201-05- TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m During 15-22 May, IG reported that ash plumes intermittently visible from Tungurahua rose to altitudes of 5.1-7 km (16,700-23,000 ft) a.s.l. and drifted mainly W, NW, and E. Ashfall was reported from areas SW and W during 16-17 May, SW on 19 May, and W and NW during 20-21 May. Lahars and muddy waters traveled down W, NW, and N ravines during 15 and 17-19 May and caused the road to Baños to close on 18 May. Lahars that traveled in the Bilbao sector and down NW ravines on 20 May blocked the Baños-Penipe highway and obstructed the route between Ambato and Baños for about 6 hours. Muddy waters traveled down ravines to the N. 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 INGEMMET reported that during 16-17 May, ash and gas plumes from Ubinas rose to altitudes of 5.8-7.7 km (19,000-25,300 ft) a.s.l. and drifted SW, SE, and E. Based on pilot reports and satellite imagery, the Buenos Aires VAAC reported that continuous emissions produced ash plumes that rose to altitudes of 5.6-9.1 km (18,000-30,000 ft) a.s.l. during 17 and 19-22 May. Plumes drifted ESE, SE, and 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. Sources: Instituto Geológical Minero y Metalúrgico (INGEMMET) http://www.ingemmet.gob.pe/, 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= +++++++++++++++++++++++++++++++++++++ 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 <http://www.volcano.si.edu/reports/usgs/> ++++++++++++++++++++++++++++++++++++++++++ ============================================================== 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. ==============================================================
