************************************************************ GVP/USGS Weekly Volcanic Activity Report 23-29 August 2006 ************************************************************ From: Sally Kuhn <kuhns@xxxxxx> GVP/USGS Weekly Volcanic Activity Report 23-29 August 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Mayon, Philippines | Tungurahua, Ecuador Ongoing Activity: | Dukono, Indonesia | Karymsky, Russia | Kilauea, USA | Lascar, Chile | Manam, Papua New Guinea | Miyake-jima, Japan | Pacaya, Guatemala | Sakura-jima, Japan | Semeru, Indonesia | Soufriere Hills, Montserrat | St. Helens, USA | Suwanose-jima, Japan | Ubinas, Perú | Ulawun, Papua New Guinea New Activity/Unrest MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev. 2,462 m According to PHIVOLCS and news reports, lava extrusion and associated rockfalls on the SE slopes of Mayon continued during 23-29 August. On 24 and 28 August, moderate gray-and-white plumes were observed drifting to the NE, SE, and WNW. 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. Sources: Philippine Institute of Volcanology and Seismology http://www.phivolcs.dost.gov.ph/news/mayon71706.html, ABS-CBN News http://www.abs-cbnnews.com/storypage.aspx?StoryId=48593, The Manila Bulletin http://www.mb.com.ph/archive_pages.php?url=http://www.mb.com.ph/issues/2006/08/29/MTNN2006082972915.html, News Balita http://news.balita.ph/html/article.php/20060828091515829 Mayon Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03= TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m During 23-27 August, visual observations of Tungurahua were impaired due to inclement weather. Based on seismic interpretation, lava continued to slowly flow NW towards Cusúa and La Hacienda. Seismicity was low and dominated by long-period earthquakes. Inclinometer measurements indicated no additional inflation on the flanks. Several United Nations agencies and other organizations provided aid for an estimated 19,000 people that remained in shelters. 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/vulcanologia/tungurahua/actividad/informet.htm, Relief Web http://www.reliefweb.int/rw/rwb.nsf/db900SID/KHII-6T47XP?OpenDocument Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= Ongoing Activity DUKONO Halmahera, Indonesia 1.70°N, 127.87°E; summit elev. 1,185 m According to the Darwin VAAC, a diffuse ash plume from Dukono was visible on satellite imagery extending NNE on 23 August. Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred since 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time. Source: Darwin Volcanic Ash Advisory Centre http://www.bom.gov.au/info/vaac/advisories.shtml Dukono Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0608-01= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Activity at Karymsky continued during 23-29 August, with 30-100 shallow earthquakes occurring daily. Based on interpretations of seismic data, ash plumes reached altitudes of 3.5 km (11,500 ft) a.s.l. A thermal anomaly in the crater was observed on 23 August. 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 23-29 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 the reporting period. Summit inflation S of Halema'uma'u caldera continued. Tremor at Pu'u 'O'o remained at a very typical moderate level. 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- LASCAR northern Chile 23.37°S, 67.73°W; summit elev. 5,592 m Several small phreatic explosions occurred at Lascar during May, July, and August. The explosions were separated in time by up to several weeks. The last observed explosion, lasting for about five minutes on 14 August, produced a plume that reached a height of 450 m above the crater (19,800 ft a.s.l.) and dispersed ESE. Geologic Summary. Lascar is the most active volcano of the northern Chilean Andes. The andesitic-to-dacitic stratovolcano contains six overlapping summit craters and lies 5 km W of an older, higher stratovolcano, Volcán Aguas Calientes. Lascar consists of two major edifices; activity began at the eastern volcano and then shifted to the western cone. The largest eruption of Lascar took place about 26,500 years ago, and following the eruption of the Tumbres scoria flow about 9,000 years ago, activity shifted back to the eastern edifice, where three overlapping craters were formed. Frequent small-to-moderate explosive eruptions have been recorded from Lascar in historical time since the mid-19th century, along with periodic larger eruptions that produced ashfall hundreds of kilometers away from the volcano. The largest historical eruption of Lascar took place in 1993 and produced pyroclastic flows that extended up to 8.5 km NW of the summit. Source: Jorge Clavero-Chilean Geological Survey (Sernageomin) and Juan Cayupi-Chilean Emergency Office (ONEMI) via the Volcano Listserv Lascar Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1505-10= MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit elev. 1,807 m During 22-23 August, emissions from Manam consisted of dark brown-to-gray ash plumes that rose 1-2 km above the summit (9,200-12,500 ft a.s.l.) and drifted W and NW. The Darwin VAAC reported that eruption plumes were visible on satellite imagery on 23 and 26 August, extending NW. Ash was not identified in the imagery. 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 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= MIYAKE-JIMA Izu Islands, Japan 34.08N, 139.53E; summit elev. 815 m The Tokyo VAAC reported that an eruption at Miyake-jima on 23 August generated plumes that reached altitudes of ~1.5 km (~5,000 ft) a.s.l. and drifted SE. Ash was not identified on satellite imagery. Geologic Summary. The circular, 8-km-wide island of Miyake-jima forms a low-angle stratovolcano with a 3-km-wide summit caldera partially filled by the summit cone Oyama (many reports call the volcano Oyama). Parasitic craters and vents dot the volcano, including maars near the coast and radially oriented fissure vents. Frequent historical eruptions have originated at vents ranging from the summit to sea level, causing much damage. The previous eruption of Miyake-jima occurred in 1983; it forced ~4,000 residents to evacuate the island. There were no injuries or fatalities reported then, but basaltic lava flows destroyed 80% of the W-flank town of Ako and reached the sea on the SW coast. Source: Tokyo Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Miyake-jima Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0804-04= PACAYA southern Guatemala 14.38°N, 90.60°W; summit elev. 2,552 m The Washington VAAC reported that emissions from Pacaya with possible ash content were visible on satellite imagery on 28 August. The plumes reached altitudes of ~3 km (~10,000 ft) a.s.l. and drifted W. A thermal anomaly was identified on the imagery. Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (MacKenney cone) grew. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions. Source: Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Pacaya Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-11= 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 eruptions at Sakura-jima on 22, 23, and 26 August generated plumes that rose to ~2.4 km (~8,000 ft) a.s.l. and drifted mainly 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= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m According to the Darwin VAAC, ash plumes from Semeru were visible on satellite imagery on 25 August. 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 Centre 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= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m During 18-25 August, the Soufrière Hills lava dome continued to grow. A marked increase of long-period and hybrid earthquakes was noted from 18 to 20 August. Based on satellite imagery and reports from the MVO, the Washington VAAC reported that continuous emissions of ash and steam produced plumes that reached altitudes of 1.5 km (5,000 ft) a.s.l. on 28 August. 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= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m During 23-29 August, the lava dome at Mount St. Helens continued to grow and produce small rockfalls. 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- SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported that explosions from Suwanose-jima produced eruption plumes that rose straight up to 1.8 km (6,000 ft) a.s.l. on 26 August. On 28 August, eruption plumes rose to altitudes of 1.5 km (5,000 ft) a.s.l. and drifted E. 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= 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 continuous emissions of ash plumes from Ubinas during 23-29 August. The plumes reached altitudes of 4.9-7.6 km (16,000-25,000 ft) a.s.l. and drifted NE, SE, and S. 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 The Darwin VAAC reported steam-and-ash plumes from Ulawun that were visible on satellite imagery on 25, 27, and 28 August. The plumes reached altitudes of 3.7 km (12,000 ft) a.s.l. and drifted NW, W, and SW. 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 ++++++++++++++++++++++++++++++++++++++++++ ============================================================== 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. ==============================================================
