************************************************** GVP/USGS Weekly Volcanic Activity Report 11-17 July 2007 http://www.volcano.si.edu/reports/usgs/ ************************************************** New Activity/Unrest: | Gamkonora, Indonesia Ongoing Activity: | Bulusan, Philippines | Karymsky, Russia | Kilauea, USA | Kliuchevskoi, Russia | Langila, Papua New Guinea | Pacaya, Guatemala | Rabaul, Papua New Guinea | Santa María, Guatemala | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador New Activity/Unrest GAMKONORA Halmahera, Indonesia 1.38°N, 127.53°E; summit elev. 5,364 m CVGHM reported that on 10 July, incandescent material from Gamkonora was propelled about 5 m above the summit and intermittently showered the flank. On 11 July, ash plumes rose to altitudes of 5.9-9.4 km (19,400-30,800 ft) a.s.l. During 12-15 July, visual observations of ash plumes were hindered by cloud cover. On 16 July, the Alert Level was lowered from 4 to 3 (on a scale of 1-4) due to a drastic decrease in seismic activity, a decline in ash plume altitudes, and the absence of incandescence observed at the summit during 11-15 July. Geologic Summary. The shifting of eruption centers on Gamkonora, at 1635 m the highest peak of Halmahera, has produced an elongated series of summit craters along a N-S trending rift. Youthful-looking lava flows originate near the cones of Gunung Alon and Popolojo, south of Gamkonora. Since its first recorded eruption in the 16th century, Gamkonora has typically produced small-to- moderate explosive eruptions. Its largest historical eruption, in 1673, was accompanied by tsunamis that inundated villages. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ Gamkonora information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0608-04= Ongoing Activity BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m On 13 July, PHIVOLCS lowered the Alert Level for Bulusan from 2 to 1 (out of 5) due to a decline in activity including decreased seismicity, below baseline sulfur dioxide output, and deflation relative to the previous survey. Steam plumes from active vents and fissures were observed. 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. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/ Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m During 6-13 July, seismic activity at Karymsky was above background levels. Based on seismic interpretation, ash plumes may have risen to altitudes of 2.5 km and 3.8 km (8,200 ft and 12,500 ft) a.s.l. on 7 and 10 July, respectively. A thermal anomaly in the crater was visible on satellite imagery during 10-11 July. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Based on pilot reports, satellite imagery, observations in the Petropavlovsk- Kamchatsky Flight Information Region (FIR), and KEMSD, the Tokyo VAAC reported that an ash plume rose to an altitude of 9.1 (30,000 ft) a.s.l. on 11 July. Based on information from KEMSD, the Tokyo VAAC reported that an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. on 16 July. Ash was not identified on satellite imagery. 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 (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml, Tokyo Volcanic Ash Advisory Center (VAAC) 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 The W vent and dominant E vent in Kilauea's Pu'u 'O'o crater fed a growing lava lake during 11-13 July. Levees built up from overflows during 11-12 July. On the S wall of West Gap pit, intermittent incandescence and fuming from new vents that opened were observed during 13-14 July. On 14 July, the level of the lava lake dropped but remained active near the E vent. On 15 July, the E and W vents erupted small lava flows that drained onto the solidifying lava lake bed. Low lava fountains were observed from West Gap pit. During 15-17 July, lava filled the pit and overflowed into the main crater. 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://volcano.wr.usgs.gov/hvostatus.php Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- KLIUCHEVSKOI Kamchatka Peninsula, Russia 56.06°N, 160.64°E; summit elev. 4,835 m KVERT reported that seismic activity at Kliuchevskoi had decreased, but remained above background levels during 6-13 July. Ash plumes were visible on satellite imagery drifting NE and NW during 5-11 July. Plumes rose to estimated altitudes of 5-6.5 km (16,400-21,300 ft) a.s.l. based on atmospheric profiles. Based on video data, ash plumes rose to an altitude of 7 km (23,000 ft) a.s.l. during 9-11 July. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m- high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions have occurred during the past 3,000 years, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive eruptions from flank craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml Kliuchevskoi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-26= LANGILA New Britain Island, Papua New Guinea 5.53°S, 148.42°E; summit elev. 1,330 m RVO reported that emission of ash plumes from Langila's Crater 2 continued during 6-7 and 9-13 July. Ash plumes rose to an altitude less than 2.3 km (7,500 ft) a.s.l. and drifted N and NW. Crater 3 was quiet. Geologic Summary. Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the N and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m. Source: Herman Patia, Rabaul Volcano Observatory Langila Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-01= PACAYA southern Guatemala 14.38°N, 90.60°W; summit elev. 2,552 m On 13 July, INSIVUMEH reported that lava on the NE flank of Pacaya's MacKenney Cone branched into three flows. Two flows traveled 100 m and 200 m to the N and one traveled 300 m to the NE. Incandescence was observed from a hornito in the summit crater. White plumes were observed. 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, Meteorologia, e Hidrologia (INSIVUMEH) 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= RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 10-11 July, ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude less than 1.2 km (3,900 ft) a.s.l. and drifted N and NW. Fine ash fell in areas downwind, including Rabaul Town. During 12-14 July, white and blue vapor plumes drifted N and NW. A mild smell of sulfur gas was reported from areas downwind. On 17 July, an explosion was accompanied by a loud booming noise and an ash plume. The flanks were showered with lava fragments. The ash plume rose to an altitude less than 1.2 km (3,900 ft) a.s.l. and drifted NW. Ashfall was reported from Rabaul Town, Malaguna, and surrounding areas. White and blue vapor plumes were observed during 14-16 July. Roaring noises were heard and incandescence was visible at night. Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the E, where its floor is flooded by Blanche Bay. Two major Holocene caldera-forming eruptions at Rabaul took place as recently as 3,500 and 1,400 years ago. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city. Source: Herman Patia, Rabaul Volcano Observatory Rabaul Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14= SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m During 11-12 July, INSIVUMEH reported 27 explosions from Santa María's Santiaguito lava dome complex based on seismic interpretation. Ash plumes from the explosions drifted SW. Explosions from Caliente dome on 13 July produced ash plumes that rose to altitudes of 4.3-5.3 km (14,100-17,400 ft) a.s.l. and drifted SW. Ashfall was reported from areas downwind. Incandescent avalanches of blocks from Caliente dome were observed. Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/geofisica/boletin% 20formato.htm Santa María Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-03= SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m KVERT reported that seismic activity at Shiveluch continued above background levels during 6-13 July. Based on seismic interpretation, ash plumes rose to an altitude of 6.5 km (21,300 ft) a.s.l. during the reporting period. Gas-and- steam plumes rose to altitudes of 4-5 km (13,100-16,400 ft) a.s.l. during 9-11 July. A large thermal anomaly was detected in the crater on satellite imagery all days. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Based on information from KEMSD, the Tokyo VAAC reported that an ash plume rose to altitudes of 5.2-6.1 km (17,000-20,000 ft) a.s.l. during 16-17 July. Ash was not identified on satellite imagery. 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 (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml, Tokyo Volcanic Ash Advisory Center (VAAC) 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 MVO reported that during 6-13 July the lava dome at Soufrière Hills changed very little based on visual observations, and seismic activity was very low. Low-level rockfall activity continued. The Alert Level remained elevated at 4 (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 Data from deformation-monitoring instruments and time-lapse cameras on the volcano indicated that lava-dome growth at Mount St. Helens continued during 11- 17 July. Based on the time-lapse camera images, the lava dome was displaced southward and westward, at an average rate of 0.5 m per day at particular points. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. 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 IG reported that during 11-16 July, ash plumes intermittently visible from Tungurahua rose to altitudes of 5.3-7 km (17,400-23,000 ft) a.s.l. and drifted N and W. Ashfall was reported from areas SW during 11-12 and 14-16 July. On 13 July, roaring noises were heard and ?cannon shots? rattled windows of houses in areas to the W. A steam plume rose to an altitude of 5.2 km (17,100 ft) a.s.l. and drifted W. On 14 July, fumaroles were spotted on the NW flank. On 15 July, lahars traveled down W and S drainages. Lahars in a NW drainage temporarily blocked a road. ?Cannon shots? and roaring noises were heard during 15-16 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. Source: Instituto Geofísico-Escuela Poltécnica Nacional http://www.igepn.edu.ec/ Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= +++++++++++++++++++++++++++++++++++++ Sally Kuhn Sennert SI/USGS Weekly Volcanic Activity Report Editor Global Volcanism Program http://www.volcano.si.edu/reports/usgs/ Smithsonian Institution, National Museum of Natural History Department of Mineral Sciences, MRC-119 Washington, D.C., 20560 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. ==============================================================
