********************************************************** GVP/USGS Weekly Volcanic Activity Report 19-25 July 2006 ********************************************************** From: "Kuhn, Sally" <KUHNS@xxxxxx> GVP/USGS Weekly Volcanic Activity Report 19-25 July 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Karangetang, Indonesia | Mayon, Philippines | Tungurahua, Ecuador Ongoing Activity: | Canlaon, Philippines | Galeras, Colombia | Karymsky, Russia | Kilauea, USA | Merapi, Indonesia | Semeru, Indonesia | Shiveluch, Russia | Soufriere Hills, Montserrat | St. Helens, USA | Ubinas, Perú New Activity/Unrest KARANGETANG [Api Siau] Siau Island, Indonesia 2.47°N, 125.29°E; summit elev. 1,784 m The Alert Status of Karangetang was raised on 22 July from 3 to 4 (on a scale of 1-4) due to a further increase in eruptive activity since the last reporting period. On 20 July, lava flows were observed moving E toward the Kahetang and Batu Awang rivers at a maximum distance of 1.8 km from the vent, towards the Hamstring river at unknown location and distance, and S towards the Bahembang river at a maximum distance of 2 km. On 21 July, a pyroclastic flow originating from the upper S flank traveled 2.5 km toward the Stone river (unknown direction) and was followed by lava flows that traveled toward the Hamstring river and E towards the Kahetang river at a maximum distance of 2 km. A "thin white smoke" was seen at a height of ~350 m above the summit (7,000 ft a.s.l.). Lava flows traveled a maximum distance of ~2.3 km towards the Hamstring river and S towards the Bahembang river during 22-23 and 25 July. 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= MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev. 2,462 m PHIVOLCS reported that during 19-24 July lava flows from Mayon traveled SSE a maximum distance of 4 km from the summit toward the Bonga gully and branched off to the W and E. Incandescent blocks shed from the toe and margins of the flows were visible at night and traveled SE. Ash plumes generated from the rolling blocks produced light ash fall 8.5 km E of the summit in Sta. Misericordia. On 20 July, pyroclastic flows were observed on the SE slopes prompting ~100 families to evacuate. On 22 July, lava flows advanced NE towards the Mabinit channel. The lava flows were within the 6 km radius Permanent Danger Zone. 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, Jun P. Yap and Agence France-Presse http://www.tribune.net.ph/nation/20060721nat1.html, Gulf News http://archive.gulfnews.com/articles/06/07/22/10054127.html 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 19-25 July, visual observations of Tungurahua were limited due to heavy cloud cover. Based on seismic interpretations, daily explosions recorded during the week were mostly small to moderate in intensity. Small pyroclastic flows descended NW a maximum distance of 1 km on 21 and 23 July. Steam-and-ash plumes were observed during 19-22 and 24 July and reached maximum heights of 5 km above the summit (32,900 ft a.s.l.) on 21 July. According to the Washington VAAC, pilots reported on 19, 22, and 23 July that ash plumes reached altitudes of 10.7 km (35,000 ft) a.s.l. and drifted predominantly W. A hot spot was visible on satellite imagery from 19 to 22 July. 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 Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= Ongoing Activity CANLAON Philippines 10.41°N, 123.13°E; summit elev. 2,435 m Based on interpretations of seismic data, an explosion at Canlaon that lasted more than 10 minutes occurred on 23 July. An ash column was not observed due to cloud cover. Trace deposits of ash fell up to 9 km ENE of the crater in the neighborhoods of Pula, Malaiba, and Lumapao. On 24 July, PHIVOLCS reported a total of 16 volcanic earthquakes, 3 short-duration tremors, and 2 earthquakes indicating small explosions. Ash was not observed. 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 On 17 July, INGEOMINAS reported that after the 12 July eruption of Galeras, seismic activity decreased considerably. Observations of the dome and secondary craters in the W sector post-12 July, showed small physical changes. Gas plumes with little steam content were observed without associated seismic activity. Galeras remained at Alert Level 3 (changes in the behavior of volcanic activity have been noted). 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 Based on interpretations of seismic data from Karymsky during 15-21 July, KVERT reported that ash plumes reached altitudes of 6 km (19,700 ft) a.s.l. According to the Tokyo VAAC, the Kamchatkan Experimental and Methodical Seismological Department (KEMSD) reported that on 23 and 24 July ash plumes reached altitudes of 6.7 km (22,000 ft) a.s.l. Approximately 180-400 shallow earthquakes occurred daily during the reporting period. A thermal anomaly in the crater was observed during 15-20 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 19-24 July, incandescence from Kilauea was observed due to reflections from the fumes over East Pond and January vents and the South Wall complex. On 21 July, the terminus of the Campout flow was ~1.7 km from the sea at Ka`ili`ili, about 440 m from the observed terminus on 14 July. Pu`u `O`o tremor remained at a 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 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 During 19-25 July, gas plumes at Merapi reached maximum heights of 400 m above the summit (11,000 ft a.s.l.). Lava flows were observed daily, advancing at a maximum distance of 1.5 km SE toward the Gendol River. Pyroclastic flows were not observed during the reporting period. The Alert Level remained at 3 (on a scale of 1-4). 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. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php Merapi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m Eruption plumes from Semeru were visible on satellite imagery on 18, 21, and 24 July and reached a maximum altitude of 4.3 km (14,000 ft) a.s.l. 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= SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m Eruption plumes from Shiveluch that were visible on satellite imagery on 19 July reached a maximum altitude of 5.2 km (17,000 ft) a.s.l. and drifted SE. Ash was not visible on satellite imagery. A thermal anomaly over the dome was visible on 17 and 18 July. Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large horseshoe-shaped caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. During the 1990s, intermittent explosive eruptions took place from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964. Sources: Kamchatkan Volcanic Eruption Response Team http://www.avo.alaska.edu/activity/avoreport.php?view=kaminfo, Tokyo Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Shiveluch Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1000-27= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m During 14-21 July, the Soufrière Hills lava dome grew noticeably. A blocky spine was observed on the NE side, where growth had been focused. On 18 July, the spine height was estimated at 895 m. 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 19-25 July, the lava dome at Mount St. Helens continued to grow at a slow and steady rate producing small rockfalls. Wind and rockfalls stirred up ash that occasionally rose above the crater rim or created a haze around the summit. On 25 July, a M 3.1 earthquake generated a rockfall and associated dust/ash cloud that quickly dissipated. 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- 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 during 22-24 July reached altitudes of 7 km (23,000 ft) a.s.l. and drifted SE. Ash plumes were 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 +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
