**************************************************************** GVP/USGS Weekly Volcanic Activity Report 10-16 October 2007 http://www.volcano.si.edu/reports/usgs/ **************************************************************** New Activity/Unrest: | Bezymianny, Russia | Kelut, Indonesia Ongoing Activity: | Anatahan, Mariana Islands | Batu Tara, Indonesia | Chikurachki, Russia | Fuego, Guatemala | Gamalama, Indonesia | Karangetang, Indonesia | Karymsky, Russia | Kilauea, USA | Langila, Papua New Guinea | Manam, Papua New Guinea | Rabaul, Papua New Guinea | Reventador, Ecuador | Ruapehu, New Zealand | Sangay, Ecuador | Santa María, Guatemala | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Suwanose-jima, Japan | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest BEZYMIANNY Kamchatka Peninsula, Russia 55.98°N, 160.59°E; summit elev. 2,882 m During 5-12 October, KVERT reported that seismic activity at Bezymianny was at background levels. Based on observations of satellite imagery, a thermal anomaly was present in the crater on 4, 6, 8, and 11 October. Fumarolic activity was observed during 6-7 and 10-11 October. Based on seismic interpretation, a hot avalanche probably occurred on 10 October. Based on observations of satellite imagery and seismic interpretation, a small eruption occurred on 15 October. Ash plumes drifted SE and a strong thermal anomaly was present in the crater. Based on information from KEMSD and observations of satellite imagery, the Tokyo VAAC reported that an ash plume rose to altitudes of 7.3-9.1 km (24,000-30,000 ft) a.s.l. and drifted E and SE. The level of Concern Color Code <http://www.avo.alaska.edu/color_codes.php> was raised from Yellow to Red. No ash plumes were present on 16 October, and seismicity was only slightly above background levels. The level of Concern Color Code was lowered to Orange. Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. The modern Bezymianny volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral volcano that was built between about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of Mount St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater. 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 Bezymianny Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-25= KELUT Java, Indonesia 7.93°S, 112.31°E; summit elev. 1,731 m CVGHM reported that the Alert Status of Kelut was raised on 16 October from 3 to 4 (on a scale of 1-4). During 15-28 September, gas discharge from the crater lake increased and spread in a radius of 5 m. Inflation around the summit occurred during 13-16 October. On 16 October, the temperature in the crater lake increased to 37.8 degrees C. In conjunction with the elevated Alert Status, CVGHM recommended to the local authorities that villagers within a 10 km radius should evacuate. According to a news article, about 50,000 people evacuated on 16 October. On 17 October, thousands of people returned to their homes to tend to crops and animals, and to get food. Geologic Summary. The relatively inconspicuous 1,731-m-high Kelut stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. More than 30 eruptions have been recorded from Gunung Kelut since 1000 AD. The ejection of water from the crater lake during Kelut's typically short, but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5,000 people were killed during the 1919 eruption, an ambitious engineering project sought to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels. After more than 200 people were killed in the 1966 eruption, a new deeper tunnel was constructed, lowering the lake's volume to only about 1 million cubic meters prior to the 1990 eruption. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/, Associated Press http://news.yahoo.com/s/ap/20071017/ap_on_re_as/indonesia_volcano_8;_ylt=AkcSi_ueVtCPzfHMi0LxedCnZiEB Kelut Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-28= Ongoing Activity ANATAHAN Mariana Islands, central Pacific Ocean 16.35°N, 145.67°E; summit elev. 788 m Seismic activity at Anatahan returned to background levels on 1 October and remained low through 12 October. On 12 October, the Volcanic Alert Level was lowered to Normal and the Aviation Color Code was lowered to Green <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. The elongate, 9-km-long island of Anatahan in the central Mariana Islands consists of large stratovolcano with a 2.3 x 5 km, E-W-trending compound summit caldera. The larger western caldera is 2.3 x 3 km wide, and its western rim forms the island's 790-m high point. Ponded lava flows overlain by pyroclastic deposits fill the floor of the western caldera, whose SW side is cut by a fresh-looking smaller crater. The 2-km-wide eastern caldera contained a steep-walled inner crater prior to the 2003 eruption whose floor was only 68 m above sea level. Sparseness of vegetation on the most recent lava flows on Anatahan had indicated that they were of Holocene age, but the first historical eruption of Anatahan did not occur until May 2003, when a large explosive eruption took place forming a new crater inside the eastern caldera. Source: Emergency Management Office of the Commonwealth of the Mariana Islands and the US Geological Survey Hawaiian Volcano Observatory http://hvo.wr.usgs.gov/cnmi/index.html Anatahan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0804-20= BATU TARA Lesser Sunda Islands, Indonesia 7.792°S, 123.579°E; summit elev. 748 m Based on visual observations, CVGHM lowered the Alert Level for Batu Tara to 1 (on a scale of 1-4) on 9 October. In March 2007, ash plumes rose to a maximum altitude of 4.3 km (14,000 ft) a.s.l. During 3 September-9 October, plumes rose to an altitude of approximately 1.4 km (4,600 ft) a.s.l. Based on observations of satellite imagery, the Darwin VAAC reported that an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. on 13 October and drifted N and W. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lomblen Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The only known historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. 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 Batu Tara Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0604-26= CHIKURACHKI Kuril Islands, Russia 50.325°N, 155.458°E; summit elev. 1,816 m KVERT reported that gas-and-ash plumes from Chikurachki were visible on satellite imagery and drifted NE on 7 and 10 October. Clouds obscured views of the summit on other days during 5-12 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 INSIVUMEH reported on 10 October that explosions from Fuego produced ash plumes that rose to altitudes of 4-5 km (13,000-16,400 ft) a.s.l. and drifted N and NW. Explosions were accompanied by rumbling noises and sounds resembling an aircraft engine. Avalanches due to collapses from the growing cone in the inner crater descended W into the Taniluyá and Santa Teresa ravines. 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= GAMALAMA Halmahera, Indonesia 0.80°N, 127.325°E; summit elev. 1,715 m CVGHM lowered the Alert Level for Gamalama to 1 (on a scale of 1-4) on 9 October based on visual observations of plume altitudes and a decline in seismicity. 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= KARANGETANG [Api Siau] Siau Island, Indonesia 2.47°N, 125.29°E; summit elev. 1,784 m Based on a pilot report, the Darwin VAAC reported that an ash plume from Karangetang rose to an altitude of 1.9 km (6,200 ft) a.s.l. on 13 October. 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: Darwin Volcanic Ash Advisory Centre http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Karangetang Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0607-02= 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 5-12 October. Based on seismic interpretation, ash plumes may have risen to an altitude of 5.2 km (17,100 ft) a.s.l. during the reporting period. Observations of satellite imagery revealed that a thermal anomaly was present in the crater and ash plumes drifted E during 4-8 and 10-11 October. The Level of Concern Color Code <http://www.avo.alaska.edu/color_codes.php> remained at Orange. Based on pilot reports and observations of satellite imagery, the Tokyo VAAC reported that ash plumes rose to altitudes of 4.6-5.2 km (15,000-17,100 ft) a.s.l. on 12 and 16 October. Plumes drifted SE and E. 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 during 10-16 October fissure segment D from Kilauea's 21 July fissure eruption continued to feed an advancing lava flow that occasionally overflowed its channel edges. Lava flows advanced NE and along the S margin of earlier flows. Aerial observations on 12 October revealed that the S margin of the flow field was mostly inactive. A few small earthquakes were 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- LANGILA New Britain Island, Papua New Guinea 5.53°S, 148.42°E; summit elev. 1,330 m RVO reported that emission of ash and white vapor plumes from Langila's Crater 2 continued during 1-16 October. Plumes rose to altitudes of 1.8-2.8 km (5,900-9,200 ft) a.s.l. and drifted WNW. The emissions were occasionally accompanied by roaring noises. 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= MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit elev. 1,807 m RVO reported that Manam's Main Crater and South Crater occasionally released white vapor plumes during 6-15 October. During 10-11 October, weak incandescence and occasional ash plumes from Main Crater were visible. Geologic Summary. The 10-km-wide island of Manam is one of Papua New Guinea's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1,807-m-high stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five satellitic centers are located near the island's shoreline. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during the past century into the SE avalanche valley. Frequent historical eruptions have been recorded since 1616. Source: Herman Patia, Rabaul Volcano Observatory Manam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02= RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m RVO reported that white vapor plumes rose from Rabaul caldera's Tavurvur cone during 8-16 October. Occasional explosions produced ash plumes that rose to altitudes of 1.7-2.7 km (5,600-8,900 ft) a.s.l. The plumes drifted NNE and S. Ashfall was reported downwind, including Namanula Hill and surrounding areas. The ash emissions were intermittently accompanied by roaring noises, and 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= REVENTADOR Ecuador 0.078°S, 77.656°W, summit elev. 3,562 m Based on information from the Guayaquil MWO, the Washington VAAC reported that an eruption from Reventador on 11 October produced an ash plume that rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted S. Ash was not observed on satellite imagery due to cloud cover. Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html Reventador Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-01= RUAPEHU North Island, New Zealand 39.28°S, 175.57°E; summit elev. 2,779 m The Alert Level at Ruapehu was lowered to 1 (on a scale of 0-5) on 9 October because no further eruptions have occurred since the activity on 25 September. Geologic Summary. Ruapehu, one of New Zealand's most active volcanoes, is a complex stratovolcano constructed during at least four cone-building episodes. The 110 cu km volcanic massif is elongated in a NNE-SSW direction and is surrounded by another 100 cu km ring plain of volcaniclastic debris. A single historically active vent, Crater Lake, is located in the broad summit region, but at least five other vents on the summit and flanks have been active during the Holocene. Frequent mild-to-moderate explosive eruptions have occurred in historical time from the Crater Lake vent. Lahars produced by phreatic eruptions from the summit crater lake are a hazard to a ski area on the upper flanks and to river valleys below the volcano. Source: New Zealand GeoNet Project http://www.geonet.org.nz/ Ruapehu Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0401-10= SANGAY Ecuador 2.03°S, 78.34°W; summit elev. 5,188 m Based on observations of satellite imagery and pilot reports, the Washington VAAC reported that an ash plume from Sangay rose to an altitude of 7 km (23,000 ft) a.s.l. on 12 October and drifted W. Geologic Summary. The isolated Sangay volcano, located E of the Andean crest, is the southernmost of Ecuador's volcanoes, and its most active. It has been in frequent eruption for the past several centuries. The steep-sided, 5,230-m-high glacier-covered volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the E, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. Sangay towers above the tropical jungle on the E side; on the other sides flat plains of ash from the volcano have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The more or less constant eruptive activity has caused frequent changes to the morphology of the summit crater complex. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html Sangay Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-09= SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m On 10 October, INSIVUMEH reported that explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose to an altitude of 4.4 km (14,400 ft) a.s.l. and drifted SE. A lava flow on the SW flank produced avalanches of blocks. On 12 October, lahars in multiple drainages that carried tree branches, fine sediment, and blocks of multiple sizes, flooded the Samala river (to the E and S) as far as the Pacific coast, 70 km S. 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 During 5-12 October, KVERT reported that seismic activity at Shiveluch was above background levels and small hot avalanches occurred. Based on seismic interpretation, ash plumes rose to an altitude of 6.5 km (21,300 ft) a.s.l. during 4-6 and 9-11 October. Observations of video footage indicated that gas and occasionally ash plumes rose to an altitude of 4.5 km (14,800 ft) a.s.l. on 4, 6, 7, and 11 October. Fumarolic activity was noted on 8 October. Based on observations of satellite imagery, ash plumes drifted E during 4-8 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 <http://www.avo.alaska.edu/color_codes.php>. Based on information from the KEMSD, the Tokyo VAAC reported that an eruption plume rose to an altitude of 5.2 km (17,000 ft) a.s.l. on 16 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 10-16 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and 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 indicated that during 10-16 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 an eruption plume from Suwanose-jima rose to an altitude of 1.5 km (5,000 ft) a.s.l. on 16 October and drifted E. 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 ash plumes from Tungurahua rose to altitudes of 6.2-8 km (20,300-26,200 ft) a.s.l. during 10-16 October and drifted SW, W, NW, NE, and E. Clouds inhibited observations on 14 October. Ashfall was reported in areas to the SW, W, and NW during 9-12 and 15 October. During 11-12 October, incandescent blocks were ejected above the summit and descended 300 m down the W flank. Roaring noises were reported from multiple areas on 11, 13, and 14 October. 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 and observations of satellite imagery, the Buenos Aires VAAC reported that ash plumes from Ubinas rose to altitudes of 5.5-7.6 km (18,000-25,000 ft) a.s.l. and drifted N, NNE, SE, and ESE during 11-13 and 15 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. ==============================================================
