******************************************************** GVP/USGS Weekly Volcanic Activity Report 5-11 July 2006 ******************************************************** From: Sally Kuhn <KUHNS@xxxxxx> GVP/USGS Weekly Volcanic Activity Report 5-11 July 2006 New Activity/Unrest: | Merapi, Indonesia | Soufriere Hills, Montserrat | Sulu Range, Papua New Guinea Ongoing Activity: | Colima, México | Karymsky, Russia | Kilauea, USA | Lopevi, Vanuatu | Pacaya, Guatemala | Semeru, Indonesia | St. Helens, USA | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m Gas plumes were observed during 5-11 July at Merapi and reached a maximum height of 1.2 km above the summit (3,600 ft a.s.l.) on 6 July. Due to a decrease in activity, on 10 July the Alert Level was lowered one level to 3 (on a scale of 1-4) in all areas except the S slope. 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, Agence France-Presse http://news.yahoo.com/s/afp/20060710/sc_afp/indonesiavolcano_060710102910;_ylt=AtYns042xaM4A2Hh2n6ZmNITO7gF;_ylu=X3oDMTA5bGVna3NhBHNlYwNzc3Jlb-- Merapi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m The Montserrat Volcano Observatory estimated that the Soufrière Hills lava dome volume was 27 million cubic meters on 27 June, prior to the 30 June partial lava-dome collapse, which means the growth rate during the month of June averaged about 8 cubic meters per second. On 7 July, the Alert Level was lowered to 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= SULU RANGE New Britain Island, Papua New Guinea 5.50°S, 150.942°E; summit elev. 610 m; All times are local (= UTC + 10 hours) On 10 July, the RVO reported that "forceful, dark emissions" from the Sulu Range were observed on 7 July and decreased to moderate emissions by the morning of 8 July. On 12 July, aerial inspection confirmed that emissions were coming from a NW-S-trending area between Ubia and Ululu volcanoes. The report also indicated that weak to moderate white vapor emissions were observed on 10 through 12 July and seismic activity had increased in intensity and frequency from 6 July. Loud booming and rumbling noises were accompanied by strong tremor picked up at stations at Garbuna and Ulawun volcanoes. On 11 July it was reported that there was no evidence of ash emission and that three villages north of Mount Karai had been evacuated. A large earthquake (intensity of ~7) occurred on 12 July at 0820 that disturbed the shoreline and caused the sea water to become sediment-laden. Local rivers turned muddy due to continuous ground shaking. Reports of vegetation die-off from late February had not been confirmed due to lack of resources. The Sulu Range has not been active in historical times. 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: Herman Patia and Steve Saunders, Rabaul Volcano Observatory Ongoing Activity COLIMA Western México 19.514°N, 103.62°W; summit elev. ~3,850 m Based on information from the Mexico City MWO, the Washington VAAC reported an ash emission from Colima on 8 July to an unknown height. Ash was not visible on satellite imagery. Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of the complex) on the N and the historically active Volcán de Colima on the S. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the S, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth. Source: Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Colima Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1401-04= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Based on interpretations of seismic data from Karymsky during 1-7 July, ash plumes reached altitudes of 4 km (13,100 ft) a.s.l. According to the Tokyo VAAC, the Kamchatkan Experimental and Methodical Seismological Department (KEMSD) reported that on 10 July ash plumes reached altitudes of ~5.2 km (17,000 ft) a.s.l. Approximately 100-350 shallow earthquakes occurred daily during 29 June-3 July and increased to 1000 per day during 4-5 July. A thermal anomaly in the crater was observed on 30 June, 1 July, and 6 July. 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. Sources: Kamchatkan Volcanic Eruption Response Team http://www.kscnet.ru/ivs/kvert/updates.shtml, Tokyo Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html 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 5-11 July, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae`apuki entry. Background volcanic tremor was at normal levels at Kilauea's summit, with small shallow earthquakes occurring. Volcanic 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- LOPEVI Central Islands, Vanuatu 16.507°S, 168.346°E; summit elev. 1,413 m Based on pilot reports, the Wellington VAAC reported that an eruption plume from Lopevi on 5 July reached an unknown altitude and smoke-and-ash plumes on 8 and 9 July reached altitudes of 3.7 km (12,000 ft) a.s.l. and drifted E and SE, respectively. 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 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= PACAYA southern Guatemala 14.38°N, 90.60°W; summit elev. 2,552 m A white- and blue-colored "smoke" plume from Pacaya was observed on 5 and 7 July and drifted NW and W, and a white gas cloud on 10 July reached 800 m above the crater (11,000 ft a.s.l.) and drifted SW. Lava flows toward the NW reached lengths of 800 m. Incandescence was observed on 7 July. 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: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e Hidrologia http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm Pacaya Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-11= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m According to the Darwin VAAC, an ash plume from Semeru reached a maximum altitude of 5.5 km (18,000 ft) a.s.l. on 10 July. The plume was visible on satellite imagery. 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= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m During 5-11 July, the lava dome at Mount St. Helens continued to grow at a slow and steady rate producing 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- TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m During 5-11 July, seismic activity indicating explosions increased at Tungurahua. Incandescent blocks were ejected from the crater during 5 to 8 July, when blocks rolled approximately 1 km down the NW flank. Ash-and-steam plumes with moderate to no ash content were observed to reach maximum heights of 2.5 km above the summit (24,700 ft a.s.l.) and drifted generally to the W and NW. 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, a pilot reported that ash plumes from Ubinas on 8 and 9 July reached altitudes of 5.5 km (18,000 ft) a.s.l. and drifted NW. Ash plumes were visible on satellite imagery during 8-10 July. 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 +++++++++++++++++++++++++++++++++++++ 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/ <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. ==============================================================
