************************************************************* GVP/USGS Weekly Volcanic Activity Report 24-30 October 2007 http://www.volcano.si.edu/reports/usgs/ ************************************************************* New Activity/Unrest: | Krakatau, Indonesia | Ol Doinyo Lengai, Tanzania | Soputan, Indonesia Ongoing Activity: | Chikurachki, Russia | Fuego, Guatemala | Karymsky, Russia | Kilauea, USA | Rabaul, Papua New Guinea | Sakura-jima, Japan | Santa María, Guatemala | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Suwanose-jima, Japan | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest KRAKATAU Indonesia 6.10°S, 105.43°E; summit elev. 813 m CVGHM raised the Alert Level to 3 (on a scale of 1-4) for Krakatau on 26 October due to the presence of multiple gray plumes from Anak Krakatau and an increase in seismicity during 23-26 October. Plumes rose to an altitude of approximately 1 km (3,300 ft) a.s.l. during 23-26 and 30 October. Inclement weather resulted in only intermittent observations. Villagers and tourists were advised not go within a 3 km radius of the summit. Geologic Summary. The renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ Krakatau Information from the Global Volcanism Program http://www.vsi.esdm.go.id/portal/html/index.php OL DOINYO LENGAI Tanzania, eastern Africa 2.751°S, 35.902°E; summit elev. 2,890 m Based on pilot observations, the Toulouse VAAC reported that ash plumes from Ol Doinyo Lengai rose to altitudes of 3.2-4.6 km (10,500-15,000 ft) a.s.l. on 23 October. According to Frederick Belton's Ol Doinyo Lengai website, a pilot photographed an ash column rising vertically from the summit on approximately 25 October. Geologic Summary. The symmetrical Ol Doinyo Lengai stratovolcano is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent volcano, known as "The Mountain of God," rises abruptly above the broad plain S of Lake Natron. The cone-building stage of the volcano ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatite and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra eruptions and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater. Petrologists first observed the eruption of carbonatitic lava flows in the 1960s. Subsequent more frequent visits have documented long-term lava effusion in the summit crater that would not have been seen from the foot of the volcano. Sources: Toulouse Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/FR/messages.html, Frederick Belton's Ol Doinyo Lengai website http://www.mtsu.edu/~fbelton/lengai.html Ol Doinyo Lengai Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0202-12= SOPUTAN Sulawesi, Indonesia 1.11°N, 124.73°E; summit elev. 1,784 m Based on visual observations during clear weather, CVGHM reported that on 25, 26, 30 and 31 October, white and gray plumes from Soputan rose to altitudes of 1.8-3.3 km (5,900-10,800 ft) a.s.l. and drifted W. A lava flow traveled between 500-600 m down the W flank on 25 October and was again spotted on 30 October. The Alert Level remained at 3 (on a scale of 1-4) and villagers and tourists were advised not go within a 6 km radius of the summit. Based on pilot reports and observations of satellite imagery, the Darwin VAAC reported that ash plumes rose to an altitude of 13.7 km (45,000 ft) a.s.l. during 25-26 October and drifted WSW. Geologic Summary. The small conical volcano of Soputan on the southern rim of the Quaternary Tondano caldera is one of Sulawesi's most active volcanoes. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/, Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Soputan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0606-03= Ongoing Activity CHIKURACHKI Kuril Islands, Russia 50.325°N, 155.458°E; summit elev. 1,816 m KVERT reported that ash plumes from Chikurachki were visible on satellite imagery and drifted NW on 20 October. Clouds obscured views of the summit on other days during 19-26 October. 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= FUEGO Guatemala 14.47°N, 90.88°W; summit elev. 3,763 m Based on observations of satellite imagery, the Washington VAAC reported that multiple ash "puffs" from Fuego drifted SE on 26 October. 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: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html 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 KVERT reported that seismic activity at Karymsky was above background levels during 19-26 October. Based on seismic interpretation, ash plumes may have risen to an altitude of 3.5 km (11,500 ft) a.s.l. during the reporting period. Observations of satellite imagery revealed that a thermal anomaly was present in the crater during 19-20 and 22-24 October, and ash plumes drifted SE and S during 19-20 and 24 October. The Level of Concern Color Code <http://www.avo.alaska.edu/color_codes.php> remained at Orange. 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml 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 during 24-30 October fissure segment D from Kilauea's 21 July fissure eruption continued to feed an advancing lava flow that frequently overflowed its channel edges. Aerial observations on 26 October confirmed that a tube-fed pahoehoe flow along the N margin of the main channel advanced 2.4 km from the channel end. A few small earthquakes were located beneath Halema'uma'u crater, and along the lower SW rift zone and S flank faults during the reporting period. Tremor remained low below the summit and Pu'u 'O'o 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- 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 2.7-3.7 km (3,900-15,400 ft) a.s.l. during 29-30 October. Ashfall was reported in Rabaul town. Occasional incandescence at the summit was observed. 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: Steve Saunders, Rabaul Volcano Observatory Rabaul Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14= 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 eruption plumes from Sakura-jima rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted E on 29 October. 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. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Sakura-jima Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08= SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m Based on observations of satellite imagery, the Washington VAAC reported that ash-and-gas plumes from Santa María's Santiaguito lava dome complex rose to an altitude of (17,000 ft) a.s.l. and drifted S on 26 October. 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: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html 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 was above background levels during 19-26 October. Based on seismic interpretation, ash plumes rose to an altitude of 6.9 km (22,600 ft) a.s.l. and small hot avalanches occurred. Observations of video footage indicated that gas-and-steam plumes rose to altitudes of 3.3 km (10,800 ft) a.s.l. on 21 and 25 October. Based on observations of satellite imagery, ash plumes drifted SE on 19 October and a thermal anomaly was present in the crater every day during the reporting period. The Level of Concern Color Code remained at Orange. Based on information from the KEMSD, the Tokyo VAAC reported that eruption plumes rose to altitudes of 4.6-6.7 km (15,000-22,000 ft) a.s.l. during 27-28 and 30 October. 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 24-30 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall and pyroclastic flow activity continued. During 25-26 October, vigorous lahar activity was noted, especially to the E, including the Tar River valley. Ashfall was subsequently visible over much of N Montserrat, possibly due to rockfall activity and steam venting. On 30 October a small pyroclastic flow was observed in the Tar River valley. 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 24-30 October 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- SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported that eruption plumes from Suwanose-jima rose to an altitude of 1.5 km (5,000 ft) a.s.l. during 26-28 October and drifted E and W. Ash was not visible on satellite imagery. 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 (VAAC) 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 IG reported that although visual observations were limited due to cloud cover, ash-and-steam and ash plumes from Tungurahua rose to altitudes of 5.5-6.5 km (18,000-21,300 ft) a.s.l. during 23-30 October. Plumes drifted E, SE, SW, W, and NW. On 25 October, ashfall was reported in areas on the SW flank. During 25-26 October, incandescence was observed at the summit and noises resembling "cannon shots," blocks rolling down the flanks, and roars were heard. On 28 October, ash plumes rose to 13 km (43,000 ft) a.s.l. During 28-29 October, noises resembling blocks rolling down the flanks and roars were again heard and ashfall was reported in areas to the NNE, N, and NNW. 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= UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m Based on a Significant Meteorological Information (SIGMET) advisory, pilot reports, and observations of satellite imagery, the Buenos Aires VAAC reported that ash plumes from Ubinas rose to altitudes of 5.5-8.5 km (18,000-28,000 ft) a.s.l. and drifted NW and NE during 23-27 October. 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 (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02= +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
