********************************************************************** GVP/USGS Weekly Volcanic Activity Report 22-28 August 2007 http://www.volcano.si.edu/reports/usgs/ ********************************************************************** New Activity/Unrest: | Bagana, Papua New Guinea | Chikurachki, Russia | Gamalama, Indonesia | Pavlof, USA | Raung, Indonesia Ongoing Activity: | Cleveland, USA | Etna, Italy | Fuego, Guatemala | Karymsky, Russia | Kilauea, USA | Rabaul, Papua New Guinea | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador New Activity/Unrest BAGANA Bougainville Island, Papua New Guinea 6.14°S, 155.19°E; summit elev. 1,750 m RVO reported that an effusive lava flow from Bagana's summit crater began travelling down the SE flank on 6 August and continued flowing through 23 August. Continuous incandescence was visible down the SE flank during 6-10 August. During 6-23 August, white vapor plumes were occasionally accompanied by ash plumes that were generated by rockfalls from lava-flow edges. Based on satellite imagery, the Darwin VAAC reported that a diffuse plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. on 23 August. 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. Sources: Herman Patia, Rabaul Volcano Observatory, Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Bagana Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0505-02= CHIKURACHKI Kuril Islands, Russia 50.325°N, 155.458°E; summit elev. 1,816 m KVERT reported that visual observations of Chikurachki were inhibited by cloud cover during 22-24 August. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is actually a relatively small cone constructed on a high Pleistocene volcanic edifice. Oxidized scoria deposits covering the upper part of the young cone give it a distinctive red color. Lava flows from 1,816-m-high Chikurachki reached the sea and form capes on the NW coast; several young lava flows also emerge from beneath the scoria blanket on the eastern flank. The more erosionally modified Tatarinov group of six volcanic centers is located immediately to the S of Chikurachki. Tephrochronology gives evidence of only one eruption in historical time from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml Chikurachki Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0900-036= GAMALAMA Halmahera, Indonesia 0.80°N, 127.325°E; summit elev. 1,715 m CVGHM raised the Alert Level of Gamalama on 24 August from 1 to 2 (on a scale of 1-4) due to an increase in activity. Prior to 10 August, diffuse white plumes rose to an altitude of 1.8 km (5,900 ft) a.s.l. then increased in altitude to 2 km (6,600 ft) a.s.l. during 10-23 August. On 23 August, white and gray plumes rose to an altitude of 2.1 km (6,900 ft) a.s.l. Concurrent with the increased Alert Level, government officials banned access within a 2-km radius of the active crater. Geologic Summary. Gamalama (Peak of Ternate) is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera and is one of Indonesia's most active volcanoes. The island of Ternate was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the N, form the summit of Gamalama, which reaches 1,715 m. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ Gamalama Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0608-06= PAVLOF Alaska, USA 55.42°N, 161.887°W; summit elev. 2,519 m Seismic activity at Pavlof remained elevated during 22-28 August. A strong thermal anomaly was present at the summit on satellite imagery on 22, 24, 25, and 28 August; clouds inhibited observations on other days. Based on pilot reports and calculations using satellite imagery, a steam-and-ash plume rose to an altitude between 3-5.5 km (10,000-18,000 ft) a.s.l. On 25 August, seismic events and explosions were more energetic and a signal suggesting a large lahar was noted. Plume altitudes from previous days and seismic interpretation indicated that an ash plume rose to an altitude of 6.1 km (20,000 ft) a.s.l. on 26 and 28 August. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavolf, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing strombolian to vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption of Pavlof took place in 1911, at the end of a 5-year-long eruptive episode; a fissure opened on the northern flank of the volcano, ejecting large blocks and issuing lava flows. Source: Alaska Volcano Observatory http://www.avo.alaska.edu/ Pavlof information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1102-03- RAUNG Java, Indonesia 8.12°S, 114.04°E; summit elev. 3,332 m Based on observations of satellite imagery, the Darwin VAAC reported that an ash plume from Raung rose to an altitude of 4.6 km (15,000 ft) a.s.l. during 26-27 August and drifted E. Geologic Summary. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The 3,332-m-high, unvegetated summit of Gunung Raung is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km from the volcano, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively. Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.bom.gov.au/info/vaac/advisories.shtml Raung Reports from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-34= Ongoing Activity CLEVELAND Aleutian Islands, USA 52.82°N, 169.95°W; summit elev. 1,730 m Clouds obscured satellite and web camera views of Cleveland volcano during 22-28 August. A clear view of the crater on 23 and 28 August revealed thermal anomalies at the summit. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. The symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks. Source: Alaska Volcano Observatory http://www.avo.alaska.edu/ Cleveland Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1101-24- ETNA Sicily, Italy 37.73°N, 15.00°E; summit elev. 3,315 m On 15 August, the South East Crater at the summit of Etna produced ash emissions from a depression on the E flank. A resultant ash plume rose a few tens of meters and quickly dispersed. Ashfall formed a red deposit on the flanks of the South East Crater cone. Based on observations using the summit web camera, incandescent blocks associated with energetic emissions of ash were propelled out of the depression on 21 August. A field assessment on 22 August revealed that the ash emissions were associated with collapses within the depression. During 23-24 August, the ash emissions increased in frequency and erupted incandescent blocks were again observed. Geologic Summary. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna's summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania. Source: Istituto Nazionale di Geofisica e Vulcanologia Sezione di Catania http://www.ct.ingv.it/ Etna Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0101-06= FUEGO Guatemala 14.47°N, 90.88°W; summit elev. 3,763 m On 24 August, INSIVUMEH reported that fumarolic plumes from Fuego rose to an altitude of 3.9 km (12,800 ft) a.s.l. and drifted W. A lahar carried tree trunks, branches, and blocks down the Lajas drainage to the SE. A lahar again affected the drainage on 27 August. Explosions on 28 August produced ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l. Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm Fuego Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-09= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Seismic activity at Karymsky was above background levels during 17-24 August, with 300-800 shallow earthquakes occurring daily. Based on seismic interpretation, ash plumes may have risen to an altitude of 5.7 km (18,700 ft) a.s.l. Observations of satellite imagery revealed that a thermal anomaly was present in the crater on 20 and 23 August. The Level of Concern Color Code remained at Orange. Based on information from KEMSD, eruption plumes rose to estimated altitudes of 5.8 km and 4 km (19,000 ft and 13,000 ft) a.s.l. on 23 and 25 August, respectively. 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 HVO reported that fissure segment D from Kilauea's 21 July fissure eruption continued to feed an advancing 'a'a lava flow during 22-28 August. In the last several weeks, four 'a'a flows had started from the open lava channel fed by Fissure D. From the second flow, each had advanced along the N edge of the previous one. The first two flows advanced a total of 6.3 km from the fissure source by 24 August. On 25 August, HVO geologists confirmed that the first three flows were inactive and the fourth flow had advanced 300 m and burned vegetation at the forest edge. During 25-26 August, the channel overflowed at a point about 1 km from the vent and spread along a section of the channel about 200-300 m long. During 27-28 August, the fourth flow was about 5.1 km from the vent and continued to advance. Incandescence was visible on the web camera from E and W vents in Pu'u 'O'o's crater on 24 and 26 August. Small earthquakes were predominantly located beneath Halema'uma'u crater and the S flank during the reporting period. 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- RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m RVO reported that ash plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 0.9-2.4 km (3,000-7,900 ft) a.s.l. during 22-29 August and drifted NW. Ashfall was reported in Rabaul Town and surrounding areas during 23-29 August. Seismic activity increased to a high level on 25 through 29 August. The ash emissions were accompanied by roaring noises. Incandescence at the summit was observed during the reporting period. 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= SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m KVERT reported that seismic activity at Shiveluch was above background levels during 17-24 August. Based on seismic interpretation, avalanches and ash plumes that rose to an altitude of 8.5 km (27,900 ft) a.s.l. occurred during the reporting period. Based on visual observation, ash plumes rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted N and NE during 17-21 August. Incandescence at the lava dome and incandescent avalanches were seen at night on 21 August. Observations of satellite imagery revealed that a thermal anomaly was present in the crater during 17-24 August. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Based on information reported from KEMSD, the Tokyo VAAC reported that eruption plumes rose to altitudes of 4.9-7.6 km (16,000-25,000 ft) a.s.l. during 24-27 August. 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 21-28 August the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. On 23 August, heavy rainfall triggered small rockfalls and four pyroclastic flows to the E down the Tar River Valley. Ash and steam emissions from the dome produced a plume that drifted W. A lahar occurred in the Belham river valley to the NW. 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 indicated that during 22-28 August lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. Clouds occasionally inhibited visual observations. 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 ash plumes from Tungurahua rose to altitudes of 6-9 km (19,700-29,500 ft) a.s.l. during 22-28 August and drifted mainly NW, W, and SW. Noises resembling the sounds made by blocks rolling down the flanks were reported during 22-26 August and explosions rattled windows in surrounding areas, including Baños 8 km to the N, on 24 and 25 August. Ashfall was reported in nearby areas, especially to the NW, W, and SW, during 25-28 August. On 28 August, lahars affected W and NW drainages, the Pampas sector, and interrupted traffic on the route between Ambato and Baños. Incandescent blocks rolled down the flanks. 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. ==============================================================
