********************************************************* SI/USGS Weekly Volcanic Activity Report 30 July-5 August 2008 ********************************************************* Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Anatahan, Mariana Islands (Central Pacific) | Chikurachki, Paramushir Island | Cleveland, Chuginadak Island | Llaima, Central Chile | Manam, Northeast of New Guinea (SW Pacific) | Okmok, Fox Islands | Reventador, Ecuador | Sumbing, Central Java (Indonesia) Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Fuego, Guatemala | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Rabaul, New Britain (SW Pacific) | Semeru, Eastern Java (Indonesia) | Shiveluch, Central Kamchatka (Russia) | Tungurahua, Ecuador The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network. Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. New Activity/Unrest ANATAHAN Mariana Islands (Central Pacific) 16.35°N, 145.67°E; summit elev. 790 m During 30 July-5 August seismic tremor from Anatahan fluctuated. Gas-and-steam plumes possibly containing some ash were occasionally visible on satellite imagery at an altitude of 1.5 km (5,000 ft) a.s.l. and below. Plumes drifted W and NW. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange. 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 whose floor prior to the 2003 eruption 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://volcano.wr.usgs.gov/cnmistatus.php CHIKURACHKI Paramushir Island 50.325°N, 155.458°E; summit elev. 1816 m Based on observations of satellite imagery, KVERT reported that during 30-31July ash plumes from Chikurachki drifted S. The level of seismicity was unknown because Chikurachki lacks dedicated seismic instruments. The Level of Concern Color Code was raised to Orange. Based on reports from KVERT, the Tokyo VAAC reported that on 1 August, an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted SE. Geologic Summary. Chikurachki, the highest volcano on Paramushir Island in the northern Kurils, is actually a relatively small cone constructed on a high Pleistocene volcanic edifice. Oxidzed scoria deposits covering the upper part of the young cone give it a distinctive red color. Lava flows from 1816-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. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m AVO reported that thermal anomalies at Cleveland's summit, detected on satellite imagery during 30 July-5 August, suggested the presence of an active lava flow. A diffuse plume drifted less than 20 km NE, N, and NW at an altitude of 6.1 km (20,000 ft) a.s.l. on 31 July. On 5 August, thermal anomalies on the W, S, and SE flanks possibly indicated the presence of pyroclastic flows or hot lahars. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange. Geologic Summary. 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 (AVO) http://www.avo.alaska.edu/ LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m SERNAGEOMIN reported that scientists observed fumarolic activity from the edges of the nested cones in Llaima's main crater during aerial observations on 29 July. Sulfur dioxide plumes rose from an area in the E crater. Tephra deposits covered parts of the SE flank. Cooled lava flows emitted on 26 and 27 July were noted on the W flank. On 31 July, fumarolic activity from the crater was reported in multiple areas around the volcano. Cloudy conditions prevented visual observations during 1-2 August. The Alert level was Yellow on 2 August. Geologic Summary. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other to the SE. The massive 3,125-m-high, glacier-covered stratovolcano has a volume of 400 cu km. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following eruption of the 24 cu km Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7,200 years ago, construction of the present edifice began, characterized by Strombolian, Hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/index.php MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m Based on observations of satellite imagery and information from RVO, the Darwin VAAC reported that on 30 July a low-level plume from Manam rose to an altitude 2.4 km (8,000 ft) a.s.l. and drifted NW. Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic 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. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html OKMOK Fox Islands 53.43°N, 168.13°W; summit elev. 1073 m Based on observations of satellite imagery and pilot reports, AVO reported that ash plumes from Okmok rose to altitudes of 4.6-10.7 km (15,000-35,000 ft) a.s.l. and drifted SW, W, N, NNE, and SE. On 30 July, seismicity alternated between continuous and pulsating volcanic tremor. The Volcano Alert Level was lowered to Watch and the Aviation Color Code was lowered to Orange. On 31 July, reports from a fishing boat 11.3 km N indicated no visibility due to ashfall. Strong volcanic tremor on 2 August prompted AVO to raise the Volcano Alert Level to Warning and the Aviation Color Code to Red. Cloudy conditions prevented satellite observations. Later that day, AVO geologists in the area reported that ash-and-steam plumes rose to minimum altitude of 6.1 km (20,000 ft) a.s.l. The seismicity decreased and the Volcano Alert Level was lowered to Watch and the Aviation Color Code was lowered to Orange. Observers in Ft. Glenn on Umnak Island reported smelling sulfur and seeing a larger ash plume than earlier that day. The plume drifted ESE. On 3 August, helicopter and ground-based observers indicated a lower-altitude ash plume along with a higher steam plume. Satellite imagery revealed that ash plumes at altitudes of 9.1-10.7 km (30,000-35,000 ft) a.s.l. drifted SSW. On 4 August, ashfall reported in Nikolski had accumulated to a depth of 3 mm. During 4-5 August satellite imagery and pilot observations indicated that ash plumes rose to altitudes of 3-7.6 km (10,000-25,000 ft) a.s.l. and drifted SW and W. Geologic Summary. The broad, basaltic Okmok shield volcano, which forms the NE end of Umnak Island, has a dramatically different profile than most other Aleutian volcanoes. The summit of the low, 35-km-wide volcano is cut by two 10-km-wide calderas formed during eruptions about 8,250 and 2,400 years ago that produced dacitic pyroclastic flows that reached the coast. Numerous satellitic cones and lava domes dot the flanks of the volcano down to the coast. Some of the post-caldera cones show evidence of wave-cut lake terraces; the more recent cones, some of which have been active historically, were formed after the caldera lake disappeared. Hot springs and fumaroles are found within the caldera and at Hot Springs Cone, 20 km to the SW. Historical eruptions have occurred since 1805 from cinder cones within the caldera. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m The IG reported that seismicity from Reventador decreased during 30-31 July. On 31 July, steam-and-gas plumes with a low ash content were detected on satellite imagery and drifted W and SW. On 1 August, steam-and-gas plumes were emitted and a lava flow in the caldera was active. Diffuse ash emissions were noted on 2 August. On 3 August, IG scientists observed the lava flow in the caldera and estimated that it advanced at a rate of 100 m per day. They also heard sporadic roaring noises. Gas-and-steam plumes were noted on 5 August. 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: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/ SUMBING Central Java (Indonesia) 7.384°S, 110.070°E; summit elev. 3371 m Based on pilot observations, the Darwin VAAC reported that an eruption plume from Sumbing rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted W. Ash was not identified on satellite imagery. Geologic Summary. Gunung Sumbing is a prominent 3371-m-high stratovolcano that lies across a 1400-m-high saddle from symmetrical Sundoro volcano in central Java. Prominent flank cones are located on the north and SE sides of Sumbing, which is somewhat more dissected than Sundoro volcano. An 800-m-wide horseshoe-shaped summit crater breached to the NE is partially filled by a lava dome that fed a lava flow down to 2400 m altitude. Emplacement of the dome followed the eruption of extensive pyroclastic flows down the NE flank. The only report of historical activity at Sumbing volcano, in about 1730 AD, may have produced the small phreatic craters found at the summit. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m Based on observations of satellite imagery, the Darwin VAAC reported that during 30-31 July diffuse plumes from Batu Tara rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted W. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly 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 first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that clouds obscured camera views of Chaitén's eruption plume during most of 30-31July. A glimpse on 31 July revealed that a steam-and-ash plume rose to an altitude of 1.5 km (4,900 ft) a.s.l. Explosions were heard. A steam-and-ash plume was seen at an altitude of about 3.1 km during an overflight on 31 July and drifted NE. The plume was emitted from a fracture caused by a vertical collapse of the S flank of the lava dome. A horseshoe-shaped scar on the E side of the dome, about 500 m wide and 200 m high, formed on an unknown date within the previous several days. The scar was inferred to have formed by a lateral explosion rather than collapse because hummocky morphology typical of landslide deposits was not found below the scar. Material from the explosion was transported by rivers that eventually flowed N into the Rayas River, and also fell in small lagoons at the S base of the dome. On 4 August a small steam plume possibly containing some ash was seen through another quick break in the clouds and drifted E. Geologic Summary. Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/index.php FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m INSIVUMEH reported that a lahar descended El Jute River to the SE of Fuego on 31 July, carrying fine material as well as blocks. A report on 1 August indicated that explosions produced ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l. and drifted W and SW. Rumbling noises and shockwaves occasionally accompanied the explosions. 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/ KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that seismic activity at Karymsky was above background levels during 25 July-1 August and possibly indicated that explosions produced ash plumes to an altitude of 3.7 km (12,100 ft) a.s.l. According to area volcanologists and pilots, ash plumes rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. on 25 July. Observations of satellite imagery revealed a daily thermal anomaly in the crater. The Level of Concern Color Code 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/index_eng.php KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m HVO reported that during 30 July-5 August lava flowed SE through a lava tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex to the Waikupanaha ocean entry. Explosions from the ocean entry were noted on 30 July. On 31 July, about 2.3 acres (or 25 percent) of the bench E of the ocean entry collapsed. A small lava pond at the top of one of the rootless shields was observed during an overflight. The sulfur dioxide emission rate at Pu'u 'O'o was 1,800 tonnes per day on 31 July; the average background rate is about 2,000 tonnes per day. During the reporting period, Kilauea earthquakes were variously located beneath Halema'uma'u crater, along the Koa'e fault system, N of the summit, along the S-flank faults, and along the E and SW rift zones. Beneath Halema'uma'u crater, 40 or fewer small earthquakes per day also occurred but were too small to be located more precisely. The vent in Halema'uma'u crater continued to produce a mainly white plume with minor ash content that drifted SW, then occasionally rotated SE. During 1-3 August, seismic signals resembling those from explosions were accompanied an increase in plume vigor and by the color turning temporarily brown. An event on 1 August started with a collapse of a small portion of the vent rim and was followed by ejected incandescent tephra. Night-time incandescence was seen at the base of the plume. Rushing and rock-clattering sounds were heard in the vicinity of the crater. The sulfur dioxide emission rate was high at 800 and 700 tonnes per day, on 31 July and 4 August, respectively. The pre-2008 background rate was 150-200 tonnes per day. 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 of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island. Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/ RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 25 July-4 August, ash plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 1.7-3.7 km (5,600-12,000 ft) a.s.l. and drifted W and NW. Ashfall was reported downwind in Rabaul town, Namanula Hill, Malaguna, and surrounding areas. Occasionally incandescence at the summit was observed and roaring noises were reported. During 31 July-4 August, incandescent lava fragments were ejected along with some of the more forceful ash emissions. Based on observations of satellite imagery and reports from RVO, the Darwin VAAC reported that low-level plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NW during 5-6 August. 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. Sources: Ima Itikarai, Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html SEMERU Eastern Java (Indonesia) 8.108°S, 112.92°E; summit elev. 3676 m CVGHM reported on 5 August that ash plumes from Semeru rose to altitudes of 4-4.3 km (13,100-14,100 ft) a.s.l. and were occasionally accompanied by ejected incandescent tephra. Based on visual observations and instrumental data, the Alert level remained at 2 (on a scale of 1-4). Geologic Summary. Semeru is the highest volcano on Java and one of its most active. The symmetrical stratovolcano rises abruptly to 3,676 m above coastal plains to the S and lies at the southern end of a volcanic massif extending N to the Tengger caldera. Semeru has been in almost continuous eruption since 1967. Frequent small-to-moderate Vulcanian eruptions have accompanied intermittent lava dome extrusion, and periodic pyroclastic flows and lahars have damaged villages below the volcano. A major secondary lahar on 14 May 1981 caused more than 250 deaths and damaged 16 villages. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that seismic activity at Shiveluch was slightly above background levels during 25 July-1 August. According to visual observations, small hot avalanches occasionally descended the lava dome and fumaroles were active on 18 and 22 July. Observations of satellite imagery revealed a thermal anomaly on the lava dome daily during the reporting period. The Level of Concern Color Code remained at Orange. 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 breached 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m The IG reported that during 30-31 July and 2-5 August, explosions from Tungurahua were detected by the seismic network. Although clouds occasionally prevented visual observations, ash plumes were observed that rose to altitudes of 6-9 km (19,700-29,500 ft) a.s.l. and drifted NW, W, and SW. On 30 July, explosions and noises resembling blocks rolling down the flanks were reported. Incandescence at the crater was noted on 31 July. On 31 July and 3 and 4 August blocks rolled up to 1 km down the flanks and ashfall was reported in areas to the SW and W. During 3-4 August, roaring noises were reported in multiple areas. On 4 August an explosion produced an ash plume that rose to an altitude of 13 km (42,700 ft) a.s.l. Intense ashfall was reported in areas W. The noise generated by the explosion was heard as far away as Ambato, 31 km NW. 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 all originated from 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 Politécnica Nacional (IG) http://www.igepn.edu.ec/ +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
