********************************************************* GVP/USGS Weekly Volcanic Activity Report 14-20 June 2006 ********************************************************* From: Sally Kuhn <kuhns@xxxxxx> GVP/USGS Weekly Volcanic Activity Report 14-20 June 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Bulusan, Philippines Ongoing Activity: | Bagana, Papua New Guinea | Canlaon, Philippines | Galeras, Colombia | Karymsky, Russia | Kilauea, USA | Merapi, Indonesia | Sakura-jima, Japan | Semeru, Indonesia | Soufriere Hills, Montserrat | St. Helens, USA | Tongariro, New Zealand | Tungurahua, Ecuador New Activity/Unrest BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m An explosion from a fissure W of the summit vent of Bulusan lasting approximately 13 minutes on 13 June produced an ash-and-steam cloud that reached a height of 1.5 km above the summit (10,100 ft a.s.l.) and drifted NW. Ashfall up to 7 mm thick accumulated in neighborhoods in the municipality of Juban. On 18 June, an ash producing explosion that lasted approximately 11 minutes produced an ash-and-steam cloud that also reached a height of 1.5 km above the summit (10,100 ft a.s.l.) and drifted W. Ash up to 5 mm thick fell on a W flank village. On 20 June, a mild ash-and-steam explosion lasted approximately 17 minutes. Close to 900 people were evacuated due to the 18 June activity. On 20 June, officials declared a state of disaster for Irosin, Casiguran, and Juban towns in Sorsogon province. Bulusan remained at Alert Level 2 (out of 5 levels) during 14-20 June. 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. Sources: Philippine Institute of Volcanology and Seismology http://www.phivolcs.dost.gov.ph/news/bulusan_bul_31May2006.html, Reuters http://www.alertnet.org/thenews/newsdesk/MAN201325.htm, Canadian Press http://www.canada.com/topics/news/world/story.html?id=f0dd41ca-269a-4646-83df-9254ca339926&k=11156, Philippine Information Agency http://www.pia.gov.ph/news.asp?fi=p060620.htm&no=36 Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= Ongoing Activity BAGANA Bougainville Island, Papua New Guinea 6.14°S, 155.19°E; summit elev. 1,750 m An ash-and-steam plume from Bagana was visible on satellite imagery on 18 June drifting SW. The height of the plume was not reported. 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. Source: Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/info/vaac/advisories.shtml Bagana Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0505-02= CANLAON Philippines 10.41°N, 123.13°E; summit elev. 2,435 m Minor steam-and-ash emissions that were observed from Canlaon during 13-15 June reached heights of 2 km above the summit (14,600 ft a.s.l.) and drifted primarily NE and NW. Light ashfall was observed on the volcano's upper N flanks and reached approximately 10 km E in Canlaon City. The alert status remained at Level 1, which restricted activity within 4 km of the summit. Geologic Summary. Canlaon volcano, the most active of the central Philippines, forms the highest point on the island of Negros, about 500 km ESE of Manila. The massive stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The summit of Canlaon contains a broad northern crater with a crater lake and a smaller, but higher, historically active crater to the south. Historical eruptions, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano. Source: Philippine Institute of Volcanology and Seismology http://www.phivolcs.dost.gov.ph/news/bulusan_bul_31May2006.html Canlaon Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0702-02= GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4,276 m INGEOMINAS reported that during 12-19 June, the number of pulsating ash emissions at Galeras decreased from the 5-12 June reporting period. Ash columns reached heights of 1.4 km above the summit (18,600 ft a.s.l.) on 12 June and 0.6 km above the summit (16,000 ft a.s.l.) on 15 June. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors. Source: Instituto Colombiano de Geología y Minería http://www.ingeominas.gov.co/tmsingeominas/ModuloPublicacionPortal/PublicacionPortal.asp Galeras Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1501-08= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Activity at Karymsky continued during 10-16 June, with 400-600 shallow earthquakes occurring daily. Ash plumes up to 5 km (16,400 ft) a.s.l. traveling SE were observed by pilots. A large thermal anomaly over the crater was visible on satellite imagery. 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 14-20 June, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae`apuki entry. Incandescence was visible from Drainhole vent in Pu`u `O`o's crater during 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 about 104 km2 of land on the S flank of Kilauea and building more than 200 hectares of new land. 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- MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m Gas plumes were emitted from Merapi on 14 and 15 June and reached a maximum height of 900 m above the summit (12,500 ft a.s.l.). On 14 June, a dome-collapse event, lasting approximately 3.5 hours, produced pyroclastic flows that reached a maximum distance of 7 km SE along the Gendol River. Two people assisting with evacuation efforts were trapped an underground shelter in Kaliadem village and died, the first fatalities of the current eruption. On 15 June, pyroclastic flows reached a maximum distance of 4.5 km SE along the Gendol River. According to news reports, pyroclastic flows continued during 16-19 June as a new dome grew. On 19 June, water shortages were reported. The Alert Level remained at 4, the highest level. Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately N of the major city of Yogyakarta. The steep-sided modern Merapi edifice, its upper part unvegetated due to frequent eruptive activity, was constructed to the SW of an arcuate scarp cutting the eroded older Batulawang volcano. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated and inhabited lands on the volcano's western-to-southern flanks and caused many fatalities during historical time. The volcano is the object of extensive monitoring efforts by the Merapi Volcano Observatory. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php, Deutsche Presse-Agentur http://www.playfuls.com/news_00000001070_Indonesias_Mount_Merapi_Volcano_Spews_Hot_Clouds_Volcanic_Debris_.html, The Jakarta Post http://www.thejakartapost.com/misc/PrinterFriendly.asp, Reuters http://www.alertnet.org/thenews/newsdesk/JAK211146.htm, The Associated Press http://www.cnn.com/2006/WORLD/asiapcf/06/15/indonesia.volcano.ap/index.html Merapi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m Based on information from JMA and pilot reports, the Tokyo VAAC reported that ash plumes from Sakura-jima reached altitudes of 2.1 km (7,000 ft) a.s.l. during 14, 16, and 19 June. 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, a pilot reported that ash plumes from Semeru on 14 June reached altitudes of 6.1 km (20,000 ft) a.s.l. Small ash plumes were detected on satellite imagery on 15, 17, and 18 June. 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 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 9-16 June, the Soufrière Hills lava dome continued to grow, but at a slower rate than during the 2-9 June reporting period. Vigorous ash-and-gas venting occurred from a vent to the N of the lava dome. 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 14-19 June, the lava dome at Mount St. Helens continued to grow and produce small rockfalls. According to seismic data, a medium-sized rockfall occurred on 13 June. Incandescence was observed on satellite imagery. The volcano 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- TONGARIRO New Zealand 39.13°S, 175.642°E; summit elev. 1,978 m According to GeoNet on 14 June, seismic activity at Ngauruhoe (the youngest cone of the Tongariro complex) remained elevated. The Alert Level remained at 1. Geologic Summary. Tongariro is a large andesitic volcanic massif, located immediately NE of Ruapehu volcano, that is composed of more than a dozen composite cones constructed over a period of 275,000 years. Vents along a NE-trending zone extending from Saddle Cone (below Ruapehu volcano) to Te Mari crater (including vents at the present-day location of Ngauruhoe) were active during a several hundred year long period around 10,000 years ago, producing the largest known eruptions at the Tongariro complex during the Holocene. The youngest cone of the complex, Ngauruhoe, has grown to become the highest peak of the massif since its birth about 2500 years ago. The symmetrical, steep-sided Ngauruhoe, along with its neighbor Ruapehu to the south, have been New Zealand's most active volcanoes during historical time. Source: GeoNet Data Centre http://data.geonet.org.nz/geonews/sab/ Tongariro Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0401-08= TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m Explosions and seismic activity at Tungurahua were at moderate levels during 14-20 June. Steam columns with low-to-moderate ash content reached heights of 1.5 km above the summit (21,400 ft a.s.l.) on 14-15 and 17 June and drifted W. On 16 June, ash fell in the towns of Pillate and Bilbao. 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, Washington Volcanic Ash Advisory Center 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= ============================================================== 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. ==============================================================
