********************************************************* GVP/USGS Weekly Volcanic Activity Report 8-14 March 2006 ********************************************************* From: Gari Mayberry <mayberry@xxxxxxxxxxxxxx> GVP/USGS Weekly Volcanic Activity Report 8-14 March 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | San Cristóbal, Nicaragua Ongoing Activity: | Arenal, Costa Rica | Atka, USA | Augustine, USA | Karymsky, Russia | Kilauea, USA | Manam, Papua New Guinea | Pacaya, Guatemala | Santa María, Guatemala | Semeru, Indonesia | Soufrière Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador | Veniaminof, USA New Activity/Unrest SAN CRISTÓBAL Nicaragua 12.702°N, 87.004°W; summit elev. 1,745 m According to a news report, explosions on 6 March at San Cristóbal produced columns of ash and gas that rose above the volcano. The height of the plumes was not reported. The activity ceased by 8 March and there were no evacuations. Background. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1,745-m-high youngest cone, the namesake San Cristóbal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the W of San Cristóbal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristóbal, are of Pleistocene age. Volcán Casita contains an elongated summit crater and lies immediately E of San Cristóbal; Casita was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes. Source: Associated Press http://news.yahoo.com/s/ap/20060309/ap_on_sc/nicaragua_volcano_1 San Cristóbal Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1404-02= Ongoing Activity ARENAL Costa Rica 10.46°N, 84.70°W; summit elev. 1,657 m In February, activity at Arenal's Crater C consisted of lava flows traveling SW and W, gas emission, sporadic Strombolian eruptions, and occasional avalanches from lava-flow fronts. Volcanic activity was at low levels, with few eruptions occurring and a small amount of pyroclastic material ejected. Eruptions produced ash plumes that rose ~500 m above the crater (or 7,100 ft a.s.l.). Ash and acid rain fell on the NE, E, and SE flanks. Small avalanches of volcanic material traveled down several ravines. There was only fumarolic activity at Crater D. Background. 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 ATKA Aleutian Islands, USA 52.381°N, 174.154°W; summit elev. 1,533 m AVO decreased the Concern Color Code at Korovin volcano in the Atka volcanic center from Yellow to Green (the lowest level) on 8 March <http://www.avo.alaska.edu/color_codes.php>. After raising the Concern Color Code on 22 February in response to increased seismicity, the rate of micro- earthquakes stabilized and then declined. During 1-8 March, seismicity was near background levels and no unusual activity was seen on satellite imagery or by observers. Background. The largest volcanic center in the central Aleutians, Atka consists of a central shield and Pleistocene caldera ringed by 7 or 8 satellitic volcanoes. The most prominent of these are the post-caldera cones of Korovin, Konia, Kliuchev, and Sarichef, some of which have been active in historical time. Korovin, the most frequently active volcano of the Atka volcanic center, contains a 1,533-m-high double summit with two craters located along a NW-SE line. The NW summit has a small crater, but the 1-km- wide crater of the SE cone has an unusual, open cylindrical vent of widely variable depth that sometimes contains a crater lake or a high magma column. A fresh-looking cinder cone lies on the flank of partially dissected Konia volcano. Sarichef has a symmetrical profile, and Korovin and Kliuchef are relatively uneroded and the source of most if not all historical eruptions. Source: Alaska Volcano Observatory http://www.avo.alaska.edu/activity/avoreport.php?view=update Atka Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1101-16- AUGUSTINE SW Alaska, USA 59.363°N, 153.43°W; summit elev. 1,252 m Low-level eruptive activity continued at Augustine during 3-10 March. The overall level of seismicity increased, with periods of prolonged volcanic tremor and an increase in the frequency of small volcano-tectonic earthquakes. The seismic network, particularly on the E flank, continued to record block- and-ash-flows, rock avalanches, and rockfalls that originated from the summit lava dome. Vigorous steaming was seen on 9 March, mostly from fumaroles on the S and W sides of the dome. Observations on 8 and 9 March revealed that small- scale collapses of the summit lava dome occurred regularly, usually producing block-and-ash-flows and small diffuse ash clouds. The block-and-ash-flows occurred on the E to NE sector of the volcano and extended to within ~1 km of the coastline. Airborne measurements of gas emissions on 9 March indicated both SO2 and CO2 gas in the plume. This was the first time since the fall of 2005 that CO2 had been a component of the gas plume, and likely indicated the presence of new magma entering the volcanic system. All available information indicated that the lava dome at the volcano's summit continued to grow. According to AVO, over several days before 10 March the rate of dome growth increased relative to the past several weeks, probably reflecting the influx of new magma. The Concern Color Code at Augustine remained at Orange <http://www.avo.alaska.edu/color_codes.php>. Background. Augustine volcano, rising above Kamishak Bay in the southern Cook Inlet about 290 km SW of Anchorage, is the most active volcano of the eastern Aleutian arc. It consists of a complex of overlapping summit lava domes surrounded by an apron of volcaniclastic debris that descends to the sea on all sides. Few lava flows are exposed; the flanks consist mainly of debris- avalanche and pyroclastic-flow deposits formed by repeated collapse and regrowth of the volcano's summit. The latest episode of edifice collapse occurred during Augustine's largest historical eruption in 1883; subsequent dome growth has restored the volcano to a height comparable to that prior to 1883. The oldest dated volcanic rocks on Augustine are more than 40,000 years old. At least 11 large debris avalanches have reached the sea during the past 1800-2000 years, and five major pumiceous tephras have been erupted during this interval. Historical eruptions have typically consisted of explosive activity with emplacement of pumiceous pyroclastic-flow deposits followed by lava dome extrusion with associated block-and-ash flows. Sources: Alaska Volcano Observatory http://www.avo.alaska.edu/activity/avoreport.php?view=update, Anchorage Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/AK/messages.html Augustine Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-01- KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Strombolian activity continued at Karymsky during 3-10 March. A thermal anomaly over the volcanic crater was visible on satellite imagery during the entire week. Numerous ash plumes extending up to 150 km SE and E of the volcano were also visible on satellite imagery. On 9 March, a pilot reported an ash plume at a height of ~3 km (9,850 ft) a.s.l. Karymsky remained at Concern Color Code Orange <http://www.avo.alaska.edu/color_codes.php>. Background. 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.kcs.iks.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 9-13 March, lava flowed off of a lava delta into the ocean at the East Lae`apuki entry. Background volcanic tremor was at normal levels at Kilauea's summit, with shallow earthquakes continuing to occur beneath the summit area and the upper east rift zone. Volcanic tremor reached moderate levels at Pu`u `O`o. Slight inflation and deflation occurred at the volcano. Background. 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- MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit elev. 1,807 m During 9-11 March, both summit craters at Manam released gas, and seismicity was at moderate levels. Inspections of deposits from an eruption on 27 February confirmed that pyroclastic flows traveled down the SW and SE valleys and that a lava flow was confined to the upper part of the SW valley. On 7 March, a team from RVO witnessed a pyroclastic flow down the SE valley. Scoria and ashfall affected the E part of the island between Warisi and Bokure 1. Background. 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: Rabaul Volcano Observatory Manam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02= PACAYA southern Guatemala 14.38°N, 90.60°W; summit elev. 2,552 m Strombolian explosions at Pacaya on 9 March occurred at intervals of 10-30 seconds and threw volcanic material 50-100 m above the volcano. On the evening of 12 March, there was an increase in Strombolian activity, with material reaching 150-250 m above Mackenney Cone. Background. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (MacKenney cone) grew. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions. Source: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e Hidrologia, http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm Pacaya Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-11= SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m; All times are local (= UTC - 6 hours) On 6 March around 0733, a moderate explosion at Santa María's Santiaguito lava- dome complex produced an ash plume and pyroclastic flows. A strong explosion later that day at 1025 sent an ash plume ~3 km above the volcano (or 22,200 ft a.s.l.) that deposited ash throughout the volcanic complex. The explosion was accompanied by pyroclastic flows that traveled down the volcano's NE and SW flanks. Fine ash drifted S and fell on properties in that direction. During 10-13 March, several moderate explosions occurred. On 12 March, there were avalanches of volcanic blocks and ash. On 13 March, a pyroclastic flow traveled down the S flank of Caliente Dome. Background. 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. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e Hidrologia, http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm, Washington Volcanic Ash Advisory Center 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= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m Based on information from the Center of Volcanology and Geological Hazard Mitigation (CVGHM formerly DVGHM), the Darwin VAAC reported that "ash rain" from Semeru was reported near the volcano. Ash was not visible on satellite imagery. Background. 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 3-10 March, lava-dome growth continued at Soufrière Hills in a northerly direction and the dome reached a height of ~950 m. The active lava lobe shed rockfalls and small pyroclastic flows to the W, N, and E. A very vigorous gas vent was seen on the W side of the lava dome on 8 March, above Gages valley. Small fumaroles were visible at the top of Gages valley and below the lava dome remnant that stands at the top of Gages Valley. The shortening monitored by Electronic Distance Measurement (EDM) on the NE flank of the volcano between Jack Boy Hill and Hermitage Estate since mid-February appeared to have eased. Recently processed Global Positioning System (GPS) baseline data suggested continued deflation, with the distance between Mongo Hill and South Soufrière Hill (N/S baseline) reducing, and E/W baselines remaining largely unchanged. The sulfur-dioxide flux varied greatly, but produced an overall average of 454 metric tons per day for the week. Background. 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. Sources: Montserrat Volcano Observatory http://www.mvo.ms/, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html 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 Growth of the new lava dome inside the crater of Mount St. Helens continued during 9-12 March, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. Small earthquakes occurred every several minutes, punctuated by occasional larger earthquakes. The Global Positioning System (GPS) receiver on the new lava dome showed that new lava emerging from the vent was still plowing WNW at about a meter per day. St Helens remained at Volcano Advisory (Alert Level 2); aviation color code Orange. Background. 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: USGS 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 8-10 March, several explosions with low ash content produced plumes that reached no higher than 2 km above the volcano (or 23,050 ft a.s.l.). Light drizzle produced muddy water in the gorges on the volcano's W flank, so the Baños-Penipe highway was closed for several hours. On 9 March, ash fell in the zone of Juive on the volcano's NW flank. On 10 March, ash fell in the towns of Pillate, Pondoa, Runtún, and Cusúa (on the W and NW flanks of the volcano). Background. 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, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= VENIAMINOF Alaska Peninsula, USA 56.17°N, 159.38°W; summit elev. 2,507 m During 3-10 March, seismicity at Veniaminof was low but slightly above background. Clear web camera views on 9 March showed small diffuse ash plumes extending a short distance from the intracaldera cone. On 10 March, a pilot reported low-level ash emitted form the intracaldera cone. The Concern Color Code remained at Yellow <http://www.avo.alaska.edu/color_codes.php>. Background. Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the N, is deeply notched on the W by Cone Glacier, and is covered by an ice sheet on the S. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which reaches an elevation of 2,156 m and rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface. Source: Alaska Volcano Observatory http://www.avo.alaska.edu/avo4/updates/updates.htm Veniaminof Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1102-07- ============================================================== 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. ==============================================================
