10-16 May 2006
http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Merapi, Indonesia
Ongoing Activity: | Arenal, Costa Rica | Bezymianny, Russia | Galeras, Colombia | Karymsky, Russia | Kilauea, USA | Lopevi, Vanuatu | Semeru, Indonesia | Soufriere Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador | Ubinas, Perú | Ulawun, Papua New Guinea
New Activity/Unrest
MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m; All times are local (= UTC + 7 hours)
CVGHM reported that on 11 May, gas plumes rose to ~600 m above Merapi (or 11,600 ft a.s.l.). Avalanches of incandescent material extended 200 m SE towards the Gendol River, and 1.5 km SW towards the Krasak River. Several small incandescent avalanches of volcanic material were visible from observatory posts. The new lava dome at the volcano's summit had grown to fill the gap between the 2001 lava flows and the 1997 lava flows on the W side of the summit. The lava dome reached a height above that of the 1997 lava flows. Seismicity was dominated by multi-phase earthquakes and signals associated with avalanches. On 13 May at 0940, the Alert Level was raised from 3 to 4, the highest level.
The Darwin VAAC reported that on 11 May an ash plume was visible on satellite imagery below 3.7 km (12,000 ft) a.s.l. An ash plume at an unknown height was visible on satellite imagery on 15 May.
According to news reports, after the Alert Level was raised to 4 on 13 May, about 4,500 people living near the volcano were evacuated. Intense activity occurred on 15 May, with pyroclastic flows traveling as far as 4 km to the W. By 16 May a total of about 22,000 people were evacuated; according to figures posted at the district disaster task force center about 16,870 people were evacuated from three districts in Central Java Province, and more than 5,600 others were evacuated from the Slemen district, a part of Yogyakarta Province. Activity decreased on 16 May. On 17 May pyroclastic flows traveled as far as 3 km. Local volcanologists reported that the lava dome continued to grow, but at a slower rate than during previous days.
Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately N of the major city of Yogyakarta. The steep-sided modern Merapi edifice, its upper part unvegetated due to frequent eruptive activity, was constructed to the SW of an arcuate scarp cutting the eroded older Batulawang volcano. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated and inhabited lands on the volcano's western-to-southern flanks and caused many fatalities during historical time. The volcano is the object of extensive monitoring efforts by the Merapi Volcano Observatory of the Volcanological Survey of Indonesia.
Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php,
Darwin Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html,
Associated Press http://news.yahoo.com/s/ap/20060515/ap_on_re_as/indonesia_volcano;_ylt=AiwLEIcVjuXJYQSXCL6fcSWs0NUE;_ylu=X3oDMTA3b3JuZGZhBHNlYwM3MjE -,
AFP http://news.yahoo.com/s/afp/20060516/ts_afp/indonesiavolcano_060516032400 ,
Reuters http://news.yahoo.com/s/nm/20060517/sc_nm/indonesia_merapi_dc_20
Merapi Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25=
Ongoing Activity
ARENAL Costa Rica 10.46°N, 84.70°W; summit elev. 1,657 m; All times are local (= UTC - 6 hours)
On 10 May around 1000, a pyroclastic flow traveled down Arenal's N flank. An ash-and-gas cloud was produced that drifted SW.
Geologic Summary. Conical Volcán Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1,657-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. The earliest known eruptions of Arenal took place about 7,000 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank.
Source: Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.una.ac.cr/ovsi/
Arenal Information from the Global Volcanism Program
http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1405-033
BEZYMIANNY Kamchatka Peninsula, Russia 55.98°N, 160.59°E; summit elev. 2,882 m
Following an explosive eruption at Bezymianny on 9 May, seismicity was at background levels on 10 May. In addition, fumarolic plumes were observed and lava flows probably extended from the lava dome. On 11 May the Concern Color Code at Bezymianny was reduced from Orange to Yellow. On 12 May, seismicity remained at background levels and gas-and-steam plumes were visible.
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.
Source: Kamchatkan Volcanic Eruption Response Team http://www.kscnet.ru/ivs/kvert/updates.shtml
Bezymianny Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-25=
GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4,276 m
INGEOMINAS reported that during 9-15 May, a partially solidified lava dome remained in Galeras' main crater. Seismicity and the sulfur-dioxide flux continued at low levels. Gas and sporadic ash emissions rose to low levels. Galeras remained at Alert Level 2 (likely eruption in days or weeks).
Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.
Source: Instituto Colombiano de Geología y Minería http://www.ingeominas.gov.co/tmsingeominas/ModuloPublicacionPortal/PublicacionPortal.asp
Galeras Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1501-08=
KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m
During 5-12 May, eruptive activity continued at Karymsky. Based on interpretations of seismic data, ash plumes rose to a height of ~5.3 km (17,400 ft) a.s.l. A thermal anomaly was present on satellite data when the crater was visible. Ash plumes drifted SE. KVERT warned that activity from the volcano could affect nearby low-flying aircraft. Karymsky remained at Concern Color Code Orange < http://www.avo.alaska.edu/color_codes.php>.
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 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
During 15-16 May, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae`apuki entry. No surface lava flows were visible on the Puluma pali fault scarp, as has been the case since 8 February. Kilauea's summit began to deflate on 14 May. On 16 May, inflation occurred that was accompanied by an abrupt drop in volcanic tremor at Kilauea's summit. Volcanic tremor reached moderate levels at Pu`u `O`o.
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 about 104 km2 of land on the S flank of Kilauea and building more than 200 hectares of new land.
Source: US Geological Survey Hawaiian Volcano Observatory http://volcanoes.usgs.gov/update.html
Kilauea information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-
LOPEVI Central Islands, Vanuatu 16.507°S, 168.346°E; summit elev. 1,413 m
The Wellington VAAC reported that a slow moving plume from Lopevi reached a height of 3 km (10,000 ft) a.s.l. on 10 May. On 11 May, a plume rose to 4.6 km (15,000 ft) a.s.l. and trended SE. During 12-13 May, the plume height lessened to 3 km (10,000 ft) a.s.l. as the eruption vigor reportedly decreased. According to Vanuatu's National Disaster Office, a news article reported that on 15 May an eruption at Lopevi produced heavy ashfall extending to the neighboring islands of Ambrym and Paama.
Geologic Summary. The small 7-km-wide conical island of Lopevi is one of Vanuatu's most active volcanoes. A small summit crater containing a cinder cone is breached to the NW and tops an older cone that is rimmed by the remnant of a larger crater. The basaltic-to-andesitic volcano has been active during historical time at both summit and flank vents, primarily on the NW and SE sides, producing moderate explosive eruptions and lava flows that reached the coast. Historical eruptions at the 1,413-m-high volcano date back to the mid-19th century. The island was evacuated following eruptions in 1939 and 1960. The latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow that swept to the sea and a lava flow that formed a new peninsula on the western coast.
Sources: Wellington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html,
Port Vila Presse http://www.news.vu/en/news/environment/060515-Vanuatu-Lopevi-volcano-eruption-yet-to-be-measured.shtml
Lopevi Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-05=
SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m
An ash plume from Semeru at a height of 6.1 km (20,000 ft) a.s.l. was observed on satellite imagery.
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: Darwin VAAC http://www.bom.gov.au/info/vaac/advisories.shtml
Semeru Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-30=
SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m
During 5-12 May, the new lobe of the lava dome at Soufrière Hills that developed towards the S produced rockfalls that predominantly extended from the W to the SE. On the 12th, the lava dome volume was approximately 80 million cubic meters, having grown at an average rate of 8 cubic meters per second through April. Seismicity typical of this current growth phase was dominated by rockfall activity during the report period. The average sulfur-dioxide flux during the week was 702 metric tons per day.
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
Analysis of photographs revealed that a slab of rock approximately 50,000 cubic meters in volume was shed from the N margin of the growing spine at Mt. St. Helens sometime during 6-7 May. This activity probably coincided with a large seismic signal recorded on the night of 7 May. Rock-avalanche deposits extended a few hundred meters to the NE. The avalanche was accompanied by an ash cloud. The spine continued to grow during 10-15 May, producing rockfalls that intensified on the evening of 14 May. Incandescence was visible on satellite imagery. The volcano remained at Volcano Advisory (Alert Level 2); aviation color code Orange.
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
During 15-16 May, small-to-moderate explosions at Tungurahua produced plumes composed of gas, steam, and small amounts of ash. A news article reported that on 15 May blasts could be heard within 20 km of the volcano, and a moderate-to-large explosion was heard in nearby communities. On 16 May, a plume reached a height of ~2 km above the crater (or 23,000 ft a.s.l.) and drifted W.
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.
Sources: Instituto Geofisico-Escuela Poltecnica Nacional http://www.igepn.edu.ec/vulcanologia/tungurahua/actividad/informet.htm ,
Domincan Today
http://www.dominicantoday.com/app/article.aspx?id=13453
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 information from significant meteorological advisories (SIGMET) and pilot reports, the Buenos Aires VAAC reported that ash emitted from Ubinas during 9-11 and 13-14 May rose to a maximum height of 7.3 km (24,000 ft) a.s.l.
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 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=
ULAWUN New Britain Island, Papua New Guinea 5.04°S, 151.34°E; summit elev. 2,334 m
On 14 May, an ash plume from Ulawun of unknown height was visible on satellite imagery.
Geologic Summary. The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
Source: Darwin Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
Ulawun Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-12=
*********************************************************
Gari Mayberry
US Geological Survey/Global Volcanism Program
Smithsonian Institution
National Museum of Natural History MRC-119
Dept. of Mineral Sciences
Washington, DC 20560-0119
Phone: 202.633.1805
Fax: 202.357.2476
mayberry@xxxxxxxxxxxxxx
http://www.volcano.si.edu/reports/usgs/
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