********************************************* GVP/USGS Weekly Volcanic Activity Report 2-8 May 2007 http://www.volcano.si.edu/reports/usgs/ ********************************************* New Activity/Unrest: | Etna, Italy | Lopevi, Vanuatu | Piton de la Fournaise, Reunion Island | Turrialba, Costa Rica Ongoing Activity: | Ambrym, Vanuatu | Batu Tara, Indonesia | Karymsky, Russia | Kilauea, USA | Kliuchevskoi, Russia | Manam, Papua New Guinea | Rabaul, Papua New Guinea | Sangay, Ecuador | Semeru, Indonesia | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Suwanose-jima, Japan | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest ETNA Sicily, Italy 37.73°N, 15.00°E; summit elev. 3,315 m A summit eruption that occurred at Etna on 29 April began with an increase in volcanic tremor and was followed by lava fountaining and a vertical ash plume. Lava flows traveled E within the Valle del Bove. The INGV-CT monitoring web cameras showed that the eruption lasted about 8-9 hours. 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: Istituto Nazionale di Geofisica e Vulcanologia Sezione di Catania http://www.ct.ingv.it/ Etna Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0101-06= LOPEVI Central Islands, Vanuatu 16.507°S, 168.346°E; summit elev. 1,413 m Based on a pilot report, the Wellington VAAC reported that an ash plume from Lopevi rose to an altitude of 2.1 km (7,000 ft) a.s.l. on 3 May. Geologic Summary. The small 7-km-wide conical island of Lopevi is one of Vanuatu's most active volcanoes. A small summit crater containing a cinder cone is breached to the NW and tops an older cone that is rimmed by the remnant of a larger crater. The basaltic-to-andesitic volcano has been active during historical time at both summit and flank vents, primarily on the NW and SE sides, producing moderate explosive eruptions and lava flows that reached the coast. Historical eruptions at the 1,413-m-high volcano date back to the mid- 19th century. The island was evacuated following eruptions in 1939 and 1960. The latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow that swept to the sea and a lava flow that formed a new peninsula on the western coast. Source: Wellington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html Lopevi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-05= PITON DE LA FOURNAISE Réunion Island, Indian Ocean 21.23°S, 55.71°E; summit elev. 2,631 m OVPDLF reported that the eruption of Piton de la Fournaise ceased on 1 May. During 2-7 May, seismicity continued at and below the summit, and also indicated a large number of landslides from Dolomieu crater walls. On 3 May, OVPDLF reported that in total, lava flows up to 30-40 m thick covered an estimated four square kilometers. The total estimated erupted volume was 120 million cubic meters, making this event one of the largest known historical eruptions of Piton de la Fournaise. Recent more accurate measurements indicated that Dolomieu crater collapsed to a depth of 350-360 m. Geologic Summary. The massive Piton de la Fournaise shield volcano on the island of Réunion is one of the world's most active volcanoes. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest of three large calderas. This latter caldera is 8 km wide and is breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows within the caldera, have been documented since the 17th century. Sources: Observatoire Volcanologique du Piton de la Fournaise (OVPDLF) http://ovpf.univ-reunion.fr/, Thomas Staudacher, Observatoire Volcanologique du Piton de la Fournaise (OVPDLF) via the Volcano Listserv http://www.volcano.si.edu/reports/volclist/ Piton de la Fournaise Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0303-02= TURRIALBA Costa Rica 10.025°N, 83.767°W; summit elev. 3,340 m On 6 May, scientists from OVSICORI declared a Low Alert Level for Turrialba based on rapid changes during the previous three months, and intensified their fieldwork and data collection efforts. During aerial observation in February 2007, trees looked yellowish due to sustained gas emissions from the W crater. Vegetation growth was noted in previously burned areas on the W and SW flanks near the summit. On 21 April, a hot area (40º C) was noted 1.5 km SW of the summit, at the base of the volcanic edifice, that coincides with the WSW-ENE- trending Ariete fault. On 2 May, two larger hot and fuming spots were documented along the same fault, about 200 m SW of the first area. The vapor plumes were spotted from several kilometers away, above the forest canopy. Heat destroyed vegetation in an approximately 300 square m area along the S fault?s plane. Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m wide summit depression that is breached to the NE. Most activity at Turrialba originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred at Turrialba during the past 3500 years. Turrialba has been quiescent since a series of explosive eruptions during the 19th century that were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters. Source: Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/ Turrialba Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1405-07= Ongoing Activity AMBRYM Ambrym Island, Vanuatu 16.25°S, 168.12°E; summit elev. 1,334 m The Wellington VAAC reported that a pilot observed an ash plume from Ambrym on 3 May. The plume rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE. Ash was visible on satellite imagery. Geologic Summary. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations. Source: Wellington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html Ambrym Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-04= BATU TARA Lesser Sunda Islands, Indonesia 7.792°S, 123.579°E; summit elev. 748 m Based on satellite imagery and CVGHM, the Darwin VAAC reported that a diffuse ash plume from Batu Tara drifted W on 5 May. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lomblen Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The only known historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.bom.gov.au/info/vaac/advisories.shtml Batu Tara Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0604-26= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Seismic activity at Karymsky was above background levels during 27 April-4 May. A thermal anomaly was visible on satellite imagery; ash plumes were absent. 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 2-8 May, lava from Kilauea continued to flow SE across a lava delta into the ocean at the Kamokuna entry. 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 was scattered at the summit, upper E rift zone, and S-flank areas. Tremor remained at moderate levels. During 3-4 May, large channelized a?a? flows descended down the pali on the Campout flow. On 4 May, a sheet flow ponded lava at the base of the Royal Gardens sub- division. On 8 May, HVO scientists reported that for the past several months, Kilauea caldera widened at a rate of 1.5 cm/month and Pu'u 'O'o cone was slowly collapsing, as indicated by new cracks on the S flank. Subsidence of the cone?s N flank at a rate of 1 cm/month was also measured. 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- KLIUCHEVSKOI Kamchatka Peninsula, Russia 56.06°N, 160.64°E; summit elev. 4,835 m Based on observations and video data, KVERT reported that Strombolian activity occurred at Kliuchevskoi during 27 April-4 May. Seismic activity continued above background levels and a thermal anomaly in the crater was detected on satellite imagery. Mudflows and lava flows continued to advance on the NW flank. Phreatic activity and ash plumes from lava-flow fronts were noted. Gas- and-steam plumes containing ash rose to altitudes of 6.2 km (20,400 ft) a.s.l. during the reporting period and were visible on satellite imagery drifting S and SE. Based on information from KVERT, the Tokyo VAAC reported that ash plumes rose to an altitude of 5.2 (17,000 ft) a.s.l. and drifted NE on 3 May. According to a news article, an ash plume rose to altitudes of 5.3-5.5 km (17,400-18,000 ft) a.s.l. and drifted NE on 7 May. Ashfall was reported from the town of Klyuchi, about 30 km to the NE. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. 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. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html, Itar-Tass http://www.itar-tass.com/eng/level2.html?NewsID=11503305&PageNum=0 Kliuchevskoi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-26= MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit elev. 1,807 m RVO reported that Manam?s Main Crater and South Crater occasionally released white vapor plumes during 1-5 May. Weak incandescence was visible from Main Crater on 2 and 4 May. Seismicity was at low levels. Based on information from RVO and satellite imagery, the Darwin VAAC reported that a diffuse plume drifted W on 6 May. Geologic Summary. The 10-km-wide island of Manam is one of Papua New Guinea's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1,807-m-high 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. Five satellitic centers are located near the island's shoreline. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during the past century into the SE avalanche valley. Frequent historical eruptions have been recorded since 1616. Sources: Herman Patia, Rabaul Volcano Observatory, Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Manam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02= RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 29-30 April, ash emissions from Rabaul caldera's Tavurvur cone generated plumes that rose to an altitude of 1.2 km (3,900 ft) a.s.l. and drifted W. During 1-2 May, ash plumes drifted NNW; ashfall was reported from Rabaul town and surrounding areas. Occasional roaring noises were heard and incandescence was observed at night. 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= SANGAY Ecuador 2.03°S, 78.34°W; summit elev. 5,188 m Based on pilot observations, the Washington VAAC reported that an ash plume from Sangay rose to altitudes of 5.2-7.6 km (17,000-25,000 ft) a.s.l. on 4 May. On 5 May, a possible narrow ash plume was visible on satellite imagery drifting W. 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 (VAAC) 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= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m Based on satellite imagery and information from CVGHM, the Darwin VAAC reported diffuse ash plumes from Semeru at an altitude of 4.6 (15,000 ft) a.s.l. during 3-5 May. The plumes drifted SW. Geologic Summary. Semeru is the highest volcano on Java and one of its most active. The symmetrical stratovolcano rises abruptly to 3,676 m above coastal plains to the S and lies at the southern end of a volcanic massif extending N to the Tengger caldera. Semeru has been in almost continuous eruption since 1967. Frequent small-to-moderate Vulcanian eruptions have accompanied intermittent lava dome extrusion, and periodic pyroclastic flows and lahars have damaged villages below the volcano. A major secondary lahar on 14 May 1981 caused more than 250 deaths and damaged 16 villages. Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.bom.gov.au/info/vaac/advisories.shtml Semeru Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-30= 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 27 April-4 May. Based on seismic interpretation, observation, and video data, ash-and-steam plumes possibly rose to altitudes of 4-10 km (13,100- 32,800 ft) a.s.l. throughout the reporting period. Plumes were seen on satellite imagery drifting S and SW during 28-29 April and a thermal anomaly was present during 27 April-4 May. Based on visual and video data, hot avalanches originating from the lava dome were observed on 30 April. Based on information from the KEMSD, the Tokyo VAAC reported that an ash plume rose to an altitude of 4.9 km (16,000 ft) a.s.l. on 7 May. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. According to a news article, a mud avalanche damaged a 30-m stretch of road which links a district center in the east of the peninsula with the rest of the territory in the region. 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. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html, Itar-Tass http://www.itar-tass.com/eng/level2.html?NewsID=11503366&PageNum=0 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 27 April-8 May, visual observations suggested that lava-dome growth at Soufrière Hills continued at a reduced rate or ceased. Fresh deposits were evident at the head of Tyres Ghaut to the NW, the upper parts of Farrell's Plain and Tuitt's Ghaut to the N, and the upper parts of the Tar River Valley to the E. Pyroclastic activity was ongoing on the E and NE sides of the dome during 27 April-4 May and pyroclastic flows were observed in the Tar River Valley and on Farrell's plain, into Tuitt's Ghaut. 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 2-8 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- SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose- jima on 8 May. Ash was not visible on satellite imagery. Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. Suwanose-jima, one of Japan?s most frequently active volcanoes, was in a state of intermittent strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for around 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Suwanose-jima Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0802-03= TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m IG reported that lahars and muddy waters that traveled into the Pampas sector and in W and NW ravines blocked the Baños - Penipe highway during parts of 3, 4, and 6 May. During 2-3 and 5-7 May, ash plumes from Tungurahua rose to altitudes of 5.2-7 km (17,100-23,000 ft) a.s.l. and drifted NW and W. Ashfall was reported in areas about 8 km to the SW and W during 3, 6, and 7 May. The Washington VAAC reported that a diffuse ash plume was visible on satellite imagery drifting W on 8 May. Clouds occasionally inhibited visual observations during the reporting period. 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. Sources: Instituto Geofísico-Escuela Poltécnica Nacional http://www.igepn.edu.ec/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html 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 and satellite imagery, the Buenos Aires VAAC reported that ash plumes from Ubinas rose to altitudes of 5.5-9.1 km (18,000-30,000 ft) a.s.l. during 2-5 May. Plumes drifted NE, S, SE, and SW. 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= +++++++++++++++++++++++++++++++++++++ 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@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
