********************************************************** GVP/USGS Weekly Volcanic Activity Report 9-15 August 2006 ********************************************************** From: Sally Kuhn <kuhns@xxxxxx> GVP/USGS Weekly Volcanic Activity Report 9-15 August 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Augustine, USA | Mayon, Philippines Ongoing Activity: | Arenal, Costa Rica | Karangetang, Indonesia | Karymsky, Russia | Kilauea, USA | Langila, Papua New Guinea | Manam, Papua New Guinea | Sakura-jima, Japan | Santa María, Guatemala | Soufriere Hills, Montserrat | St. Helens, USA | Sulu Range, Papua New Guinea | Suwanose-jima, Japan | Tungurahua, Ecuador | Ubinas, Perú | Ulawun, Papua New Guinea New Activity/Unrest AUGUSTINE SW Alaska, USA 59.363°N, 153.43°W; summit elev. 1,252 m AVO reduced the Concern Color Code at Augustine from Yellow to Green on 9 August. Seismic, satellite, and visual data indicated a decrease in activity to background levels. No changes were seen at the summit during the previous several months. AVO warned that the lava dome and surrounding area were still unstable despite the apparent cessation of lava-dome growth. Rockfalls and avalanches were still occurring, especially on the N flank, and may continue for several weeks or months. Geologic Summary. Augustine volcano, rising above Kamishak Bay in the southern Cook Inlet about 290 km SW of Anchorage, is the most active volcano of the eastern Aleutian arc. It consists of a complex of overlapping summit lava domes surrounded by an apron of volcaniclastic debris that descends to the sea on all sides. Few lava flows are exposed; the flanks consist mainly of debris-avalanche and pyroclastic-flow deposits formed by repeated collapse and regrowth of the volcano's summit. The latest episode of edifice collapse occurred during Augustine's largest historical eruption in 1883; subsequent dome growth has restored the volcano to a height comparable to that prior to 1883. The oldest dated volcanic rocks on Augustine are more than 40,000 years old. At least 11 large debris avalanches have reached the sea during the past 1800-2000 years, and five major pumiceous tephras have been erupted during this interval. Historical eruptions have typically consisted of explosive activity with emplacement of pumiceous pyroclastic-flow deposits followed by lava dome extrusion with associated block-and-ash flows. Source: Alaska Volcano Observatory http://www.avo.alaska.edu/activity/Augustine.php Augustine Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-01- MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev. 2,462 m During 9-15 August, explosive activity continued at Mayon after a brief respite on 8 August. Based on interpretations of seismic data, minor explosions during 9-11 and 13-15 August were accompanied by lava extrusion and collapsing lava flow fronts that produced blocks and small fragments. Visual observations were usually obscured by clouds, but on 11 August an ash plume was seen drifting ESE. On 12 August, out of four explosions that occurred, one produced a pyroclastic flow that traveled over the SE and E slopes and generated a plume that rose 500 m high and drifted NE. On 15 August, a brief break in the clouds allowed for a view and confirmation of fresh pyroclastic deposits from activity the previous days. About 40,000 people remained in evacuation centers. The Extended Danger Zone of 8 km in the SE sector was still in effect. Geologic Summary. The beautifully symmetrical Mayon volcano, which rises to 2,462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes that average 35-40° and is capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from Strombolian to basaltic Plinian. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1,200 people and devastated several towns. Eruptions that began in February 2000 led PHIVOLCS to recommend on 23 February the evacuation of people within a radius of 7 km from the summit in the SE and within a 6 km radius for the rest of the volcano. Source: Philippine Institute of Volcanology and Seismology http://www.phivolcs.dost.gov.ph/news/mayon71706.html Mayon Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03= Ongoing Activity ARENAL Costa Rica 10.46°N, 84.70°W; summit elev. 1,657 m In July, activity from Arenal's Crater C consisted of lava flows traveling N, gas emission, sporadic Strombolian eruptions, and occasional avalanches from lava-flow fronts. Volcanic activity was at low levels, with few eruptions occurring and a small amount of pyroclastic material ejected. Eruptions produced ash plumes that rose ~500 m above the crater (or 7,100 ft a.s.l.). Ash and acid rain fell on the NE and SE flanks. Small avalanches of volcanic material traveled down several ravines. There was only fumarolic activity at Crater D. Geologic Summary. Conical Volcán Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1,657-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. The earliest known eruptions of Arenal took place about 7,000 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank. Source: Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.una.ac.cr/ovsi/ Arenal Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1405-033 KARANGETANG [Api Siau] Siau Island, Indonesia 2.47°N, 125.29°E; summit elev. 1,784 m During 7-13 August, lava flows from Karangetang advanced E toward the Batu Awang river. Incandescent rockfalls originating from lava flow fronts were also observed. The Alert Level remained at 3. Geologic Summary. Karangetang (also known as Api Siau) lies at the northern end of the island of Siau, N of Sulawesi. The 1,784-m-high stratovolcano contains five summit craters along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth-century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/index.php?option=com_frontpage&Itemid=1 Karangetang Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0607-02= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Based on interpretations of seismic and satellite data, KVERT reported that during 5-11 August explosions from Karymsky produced ash plumes that rose to altitudes of 3.5 km (11,500 ft) a.s.l. and extended NW. Approximately 100-250 shallow earthquakes occurred daily. A thermal anomaly was present in the crater during the reporting period. Karymsky remained at Concern Color Code 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 9-15 August, 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. Incandescence was visible from the East Pond and January vents, South Wall complex, and Drainhole vent in Pu'u 'O'o's crater during most of the reporting period. Tremor remained at a very typical moderate level at Pu'u 'O'o. 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://volcanoes.usgs.gov/update.html Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- LANGILA New Britain Island, Papua New Guinea 5.53°S, 148.42°E; summit elev. 1,330 m According to the Darwin VAAC, an ash plume from Langila was visible on satellite imagery extending NW on 9 August. Ash was not identified on subsequent imagery on 9 and 10 August. Geologic Summary. Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the N and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m. Source: Darwin Volcanic Ash Advisory Centre http://www.bom.gov.au/info/vaac/advisories.shtml Langila Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-01= MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit elev. 1,807 m According to the Darwin VAAC, an ash plume from Manam was visible on satellite imagery extending NW on 9 August. Ash was not identified on subsequent imagery on 9 and 10 August. A small plume was visible on satellite imagery on 15 August. 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. Source: Darwin Volcanic Ash Advisory Centre http://www.bom.gov.au/products/IDD41300.shtml Manam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m Based on information from JMA, the Tokyo VAAC reported that an eruption at Sakura-jima on 9 August generated a plume that rose straight up to ~2.4 km (8,000 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 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= SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m Explosions at Santa María's Santiaguito lava-dome complex on 9 and 10 August produced gas-and-steam plumes with little-to-no ash content. These plumes reached heights of ~1.5 km above the summit (~17,300 ft a.s.l.) and drifted SW. 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. Source: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm Santa María Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-03= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m During 4-11 August, the Soufrière Hills lava dome continued to grow. The sulfur-dioxide flux averaged 230 metric tons per day. The Alert Level remained at 3 (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 During 9-15 August, the lava dome at Mount St. Helens continued to grow. Earthquakes occurred during the reporting period that occasionally triggered rockfalls. A steam plume was observed rising from the growing lava dome on 13 August. The hazard status remained at Volcano Advisory (Alert Level 2); aviation color code Orange. 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- SULU RANGE New Britain Island, Papua New Guinea 5.50°S, 150.942°E The RVO reported that during 31 July-2 August, seismic activity at Sulu Range was at relatively low levels. Earthquakes of Modified Mercalli Intensity 1-2 in areas S were described as being more irregular and occurring at longer intervals. Geologic Summary. The Sulu Range consists of a group of partially overlapping small stratovolcanoes in west-central New Britain off Bangula Bay. The 610-m Mount Malopu forms the high point of the basaltic-to-rhyolitic complex at its SW end. Lava Point forms a peninsula extending about 1 km into Bangula Bay at the NW side of the Sulu Range. The Walo hydrothermal area, consisting of solfataras and mud pots, lies on the coastal plain west of the SW base of the Sulu Range. Prior to 2006, no historical eruptions had occurred from the Sulu Range, although some of the cones display a relatively undissected morphology. Source: Steve Saunders, Rabaul Volcano Observatory 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 during 11-14 August. The resulting plumes reached maximum altitudes of 1.8 km (6,000 ft) a.s.l. and drifted N and W. Ash was not identified 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 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 During 9-15 August, small-to-moderate explosions at Tungurahua produced plumes composed of gas, steam, and small amounts of ash that reached heights of ~1 km (~3,300 ft.) above the summit (~19,800 ft a.s.l.). Light ashfall was reported in nearby localities during 9-10 August. On 9 and 13 August, explosions expelled blocks of incandescent material that rolled 100 m down the W flank. 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/vulcanologia/tungurahua/actividad/informet.htm 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 According to the Buenos Aires VAAC, during 8-13 August pilots reported that ash plumes emitted from Ubinas reached altitudes of between 4.9 and 5.5 km (16,000 ft-18,000 ft) a.s.l. and drifted generally N, E, and S. Ash was also visible on satellite imagery. 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 http://www.bom.gov.au/products/Volc_ash_recent.shtml Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02 ULAWUN New Britain Island, Papua New Guinea 5.04°S, 151.34°E; summit elev. 2,334 m According to the Darwin VAAC, an ash-and-steam plume from Ulawun that was reported on 15 August by the US Air Force Weather Agency rose to an altitude of ~3.7 km (~12,000 ft.) a.s.l. The plume was also visible on satellite imagery. Geologic Summary. The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater. Source: Darwin Volcanic Ash Advisory Centre http://www.bom.gov.au/products/IDD41305.shtml Ulawun Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-12= **+++++++++++++++++++++++++++++++++++++** **Sally S. Kuhn** **Global Volcanism Program** Smithsonian Institution National Museum of Natural History MRC-119 Department of Mineral Sciences Washington, D.C., 20560 http://www.volcano.si.edu/ 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. ==============================================================
