******************************************************** GVP/USGS Weekly Volcanic Activity Report June 7-13 2006 ******************************************************** From: Gari Mayberry <mayberry@xxxxxxxxxxxxxx> GVP/USGS Weekly Volcanic Activity Report 7-13 June 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Bulusan, Philippines | Canlaon, Philippines | Heard, Australia | Merapi, Indonesia | Sakura-jima, Japan | Tongariro, New Zealand Ongoing Activity: | Kilauea, USA | Semeru, Indonesia | Soufriere Hills, Montserrat | St. Helens, USA | Suwanose-jima, Japan | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m According to PHIVOLCS, an ash-and-steam cloud from Bulusan on 7 June reached a height of approximately 2 km above the summit (11,700 ft a.s.l.) and drifted N and NW. Light ashfall was reported 5 km N and trace amounts as far as 20 km N. The Alert Level was raised to 2 (scale 0 to 5), which means restricted entry within 4 km of the summit. On 10 June, an ash-and-steam cloud reached a height of ~1 km above the summit (8,400 ft a.s.l.) and drifted N and NE. A news article reported one death caused by an asthma attack from exposure to ash. 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, Associated Press http://www.sunstar.com.ph/static/net/2006/06/08/scientists.raise.alert.for.rp.volcano.following.latest.eruption.(1.07.p.m.).html, The Manila Standard Today http://www.manilastandardtoday.com/?page=news04_june10_2006 Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= CANLAON Philippines 10.41°N, 123.13°E; summit elev. 2,435 m Small explosions on 3, 10-11, and 12 June generated steam-and-ash emissions from Canlaon that reached maximum heights of 1 km above the summit (11,300 ft a.s.l.) and drifted NW and SW. Ash fell on the upper SW slopes during 10-12 June. The alert status was raised on 12 June to Alert Level 1 (scale 0 to 5), which restricts 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= HEARD Southern Indian Ocean, Australia 53.106°S, 73.513°E; summit elev. 2,745 m From 11 March to 2 June, MODVOLC (a MODIS thermal alert system) detected approximately 10 alerts from or near the summit of Big Ben on Heard Island. The area of the thermal anomaly was 1 to 2 pixels in size (1 pixel=1 km). Geologic Summary. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon volcano lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben volcano because of its extensive ice cover. The historically active Mawson Peak forms the island's 2745-m high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported in historical time at this isolated volcano, but observations are infrequent and additional activity may have occurred. Source: Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts Team http://modis.higp.hawaii.edu/ Heard Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0304-01= MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m On 8 June, according to a CVGHM report, the lava-dome growth rate at Merapi was an estimated 100 thousand cubic meters per day and the estimated volume was approximately 4 million cubic meters. An estimated volume loss of 400 thousand cubic meters on 4 June was due to a partial dome collapse of the S part of the Geger Buaya crater wall (constructed from 1910 lava flows). Gas plumes were observed almost daily during 7-13 June and reached a maximum height of 1.2 km above the summit (13,600 ft a.s.l.) on 10 June. During 8-10 June, the Darwin VAAC reported that small ash plumes were visible on satellite imagery and minor ashfall was reported to the S at the Merapi Volcano Observatory and in Yogyakarta, about 32 km (19.9 miles) away. On 8 June a pyroclastic flow, lasting 12 minutes, reached a maximum distance of 5 km SE toward the Gendol River, the predominate travel direction since the 27 May earthquake (M 6.2). According to a news report, the 8 June event prompted approximately 15,500 people to evacuate from the Sleman district to the S and the Magelang district to the W. On 13 June, the Alert Level was lowered from 4 to 3 but renewed pyroclastic-flow activity the next day again prompted a return to Alert Level 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 of the Volcanological Survey of Indonesia. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php, Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/products/IDD41290.shtml, Associated Press http://www.cnn.com/2006/WORLD/asiapcf/06/07/indonesia.volcano.ap/index.html, Reuters http://asia.news.yahoo.com/060613/3/2lu6n.html, AFX News http://www.forbes.com/home/feeds/afx/2006/06/14/afx2813966.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, the Tokyo VAAC reported that ash plumes continuing from Sakura-jima reached altitudes of 3.4 km (11,000 ft) a.s.l. during 7-12 June. JMA issued a Volcanic Advisory on 12 June. On June 10, the Sakura-jima Volcano Research Center reported an increase in low-frequency earthquakes since mid-March and in small tremors with a less than 2 minute duration since mid-May 2006. A thermal anomaly at the volcano grew in size after February 2006. 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. Sources: Sakura-jima Volcano Research Center, Disaster Prevention Research Institute (DPRI), Kyoto University http://hakone.eri.u-tokyo.ac.jp/vrc/erup/sakurajima/sakuramjima60610.html, Japan Meteorological Agency http://www.jma.go.jp/en/volcano/, Tokyo Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html, The Associated Press http://www.guardian.co.uk/worldlatest/story/0,,-5880439,00.html Sakura-jima Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08= TONGARIRO New Zealand 39.13°S, 175.642°E; summit elev. 1,978 m According to GeoNet, the number of small low-frequency earthquakes at Ngauruhoe (the youngest cone of the Tongariro complex) increased in the past 3 weeks. On 6 June, the Alert Level was raised to 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 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= Ongoing Activity KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m During 7-13 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 during the reporting period. Tremor remained at a very typical moderate level at Pu`u `O`o. The summit of Kilauea slowly inflated. 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- SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m According to the Darwin VAAC, satellite imagery showed small ash plumes from Semeru on 6 and 12 June and minor ash-and-steam plumes on 11 and 13 June, all at unknown altitudes. 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 2-9 June, the Soufrière Hills lava dome continued to grow at a high rate of 10 cubic meters per second on average (average growth rate during January-April was 6 cubic meters per second). Vigorous ash-and-gas venting occurred from a vent to the W of the lava dome. According to a pilot report and MVO, the Washington VAAC reported on 9 June that a steam plume with little ash content reached an altitude of 1.5 km (5,000 ft) a.s.l. Weak incandescence was observed on satellite imagery on 10 June. 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 7-13 June, seismic signals indicated that the lava spine continued to grow inside the crater of Mount St. Helens. On 9 June, pilots reported that an ash-and-steam plume, generated after a rockfall following a M 3.2 earthquake, reached an altitude of 4.6 km (15,000 ft) a.s.l. 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. Sources: US Geological Survey Cascades Volcano Observatory http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/framework.html, Associated Press http://seattlepi.nwsource.com/local/6420AP_WA_St_Helens.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 A pilot observed ash from Suwanose-jima on 7 June at an altitude of 2.4 km (8,000 ft) a.s.l. 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 7-13 June, small-to-moderate explosions at Tungurahua produced plumes composed of gas, steam, and small amounts of ash. On 9 and 11 June, light ashfall was reported in nearby areas. According to the Washington VAAC, night-time incandescence was observed on satellite imagery through 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. Source: 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= UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m Based on pilot reports, ash clouds identified from Ubinas during 9-11 June reached altitudes of 6.7 km (22,000 ft) a.s.l. and drifted E and SW. According to news articles, approximately 550 families were evacuated on 10 and 11 June. Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Sources: Buenos Aires Volcanic Ash Advisory Center http://www.bom.gov.au/products/Volc_ash_recent.shtml, Dominican Today http://www.dominicantoday.com/app/article.aspx?id=14193 Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02 ============================================================== 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. ==============================================================
