***************************************** GVP/USGS Weekly Volcanic Activity Report 11-17 January 2006 ***************************************** From: Ed Venzke <venzke@xxxxxxxxxxxxxx> http://www.volcano.si.edu/reports/usgs New Activity/Unrest: | Augustine, USA | Martin, USA Ongoing Activity: | Colima, Mixico | Dukono, Indonesia | Fuego, Guatemala | Galeras, Colombia | Kilauea, USA | Santa Ana, El Salvador | Santa Marma, Guatemala | Soufrihre Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador New Activity/Unrest AUGUSTINE SW Alaska, USA 59.3630N, 153.430W; summit elev. 1,252 m; All times are local (= UTC 9 hours) Explosive activity began at Augustine on 11 January. The day before, AVO increased the Concern Color Code from Yellow to Orange when seismicity began to increase at the volcano <http://www.avo.alaska.edu/color_codes.php>. On 11 January at 0444 seismic signals began to be recorded that were interpreted as being associated with explosions at Augustines summit. The Concern Color Code was increased to Red, the highest level. Another explosion occurred at 0513, and satellite imagery confirmed that an ash plume was produced that rose to ~9.1 km (30,000 ft) a.s.l. and drifted N and E. An ashfall advisory was issued by the National Weather Service. Seismicity decreased after the explosions. During a flight over the volcano, scientists saw volcanic mudflows on the E, S, and W sides of the volcano. Minor rock and snow avalanche deposits were visible high on the SW part of the edifice. According to news articles, several flights were canceled or diverted due to ash in air space. On 12 January, the Concern Color Code was reduced to Orange. On 13 January, seismicity began to increase. An eruption on the 13th from about 0355 to 0439 produced an ash plume to 10.4 km (34,000 ft) a.s.l. On the 13th, the volcano entered a period of repetitive and explosive eruptions, with explosions occurring at 0444, 0847, 1122, and 1640. Each event produced ash plumes, mudflows, and pyroclastic flows. The ash plumes produced from these eruptions rose higher than 9.1 km (30,000 ft) a.s.l. Ash drifted ESE and a small amount of ash fell in communities of the SW Kenai Peninsula. Explosions on the 13th at 1858 and on the 14th at 0014 were similar in size and duration as the previous four. In response to these eruptions, the National Weather Service issued an ashfall advisory for the western Kenai Peninsula S of Ninilchik. No explosions were recorded later on the 14th. The level of seismic activity declined after an explosion on 14 January at 0016, so the Concern Color Code was reduced to Orange on 15 January at 0945. Observations on 16 January confirmed that pyroclastic deposits were widespread on the volcanos flanks, as seen in web camera images. Also, a small lava dome appeared to have extruded at the summit. AVO reported on the 16th that the level of seismic activity at the volcano remained above background. It is likely, but not certain, that further explosive activity will occur. Explosive events similar to those of 13 and 14 January could occur with little or no warning. A strong seismic signal on 17 January marked the onset of an explosive eruption. AVO changed the level of concern color code from ORANGE to RED. 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, Los Angeles Times http://www.latimes.com/news/nationworld/nation/la-na- briefs12.2jan12,0,3705867.story?coll=la-headlines-nation Augustine Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-01- MARTIN Alaska, USA 58.1720N, 155.3610W; summit elev. 1,863 Increased seismicity occurred at Martin during 8 January until at least 15 January. About 300 earthquakes were recorded during 2 days, in contrast to the background rate of ~25 earthquakes per month since the seismic network was installed in 1996. AVO increased the Concern Color Code to Yellow <http://www.avo.alaska.edu/color_codes.php>. AVO reported that swarms of earthquakes of this nature are common at volcanoes such as Martin, and do not suggest that eruptive activity is imminent. Satellite data showed nothing unusual, although steaming is frequently observed at the volcano. Background. The mostly ice-covered Mount Martin stratovolcano lies at the SW end of the Katmai volcano cluster in Katmai National Park. The volcano was named for George C. Martin, the first person to visit and describe the Katmai area after the 1912 eruption. Mount Martin is capped by a 300-m-wide summit crater, which is ice-free because of an almost-constant steam plume and contains a shallow acidic lake. The edifice of Martin volcano overlies glaciated lava flows of the adjacent mid- to late-Pleistocene Alagoshak volcano on the WSW and was constructed entirely during the Holocene. Mount Martin consists of a small fragmental cone that was the source of ten thick overlapping blocky dacitic lava flows, largely uneroded by glaciers, that descend 10 km to the NW, cover 31 sq km, and form about 95% of the eruptive volume of the volcano. Two reports of historical eruptions that originated from uncertain sources were attributed by Muller et al. (1954) to Martin. Source: Alaska Volcano Observatory http://www.avo.alaska.edu/activity/avoreport.php?view=update Martin Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1102-14- Ongoing Activity COLIMA Western Mixico 19.5140N, 103.620W; summit elev. ~3,850 m During 11-15 January, several small explosions at Colima produced ash plumes. The highest rising ash plume was produced by an explosion on 11 November and reached ~9.1 km (30,000 ft) a.s.l. The plume drifted ENE. Background. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of the complex) on the N and the historically active Volcan de Colima on the S. Volcan de Colima (also known as Volcan Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the S, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth. Sources: Universidad de Colima http://www.ucol.mx/volcan/, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html Colima Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1401-04= DUKONO Halmahera, Indonesia 1.700N, 127.870E; summit elev. 1,185 m Ash from Dukono was visible on satellite imagery on 12 January at a height of ~3 km (10,000 ft) a.s.l., extending SW. Background. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred since 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time. Source: Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/info/vaac/advisories.shtml Dukono Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0608-01= FUEGO Guatemala 14.470N, 90.880W; summit elev. 3,763 m During 11-16 January, moderate-to-strong explosions at Fuego produced ash plumes that rose to ~1.5 km above the volcano (or 4,900 ft a.s.l.). Incandescent lava was hurled ~40 m high. During an overnight visit to a neighboring summit by Craig Chesner and Sid Halsor, Strombolian eruptions took place at roughly half-hour intervals. The morphology of Fuegos active summit vent-area contained a steep-sided cone. Background. Volcan 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. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia http://www.insivumeh.gob.gt/principal/alertas.htm Craig Chesner (Eastern Illinois University, Charleston, Illinois, USA) Sid Halsor (Wilkes Barre University, Wilkes Barre, Pennsylvania, USA) Fuego Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-09= GALERAS Colombia 1.220N, 77.370W; summit elev. 4,276 m During a flight over Galeras on 13 January, scientists saw a lava dome in the volcanos main crater. Around this time, there was an increase in the amount of seismicity and deformation. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Background. 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 Geologma y Minerma http://www.ingeominas.gov.co/tmsingeominas/ModuloPublicacionPortal/PublicacionP ortal.asp Galeras Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1501-08= KILAUEA Hawaii, USA 19.430N, 155.290W; summit elev. 1,222 m During 11-14 January, lava from Kilauea continued to enter the sea at the East Lae`apuki area, building a new lava delta. Surface lava flows were visible on the Pulama pali fault scarp. On 10 January the summit deflation switched abruptly to inflation after a loss of 5.2 microradians. Relatively high tremor occurred at this time. Tremor quickly dropped, becoming weak to moderate when deflation ended, with seismicity punctuated by a few small earthquakes. By 13 January, background volcanic tremor was near normal levels at Kilauea's summit and reached moderate levels at Pu`u `O`o. On 14 January, the lava delta was about 500 m long (parallel to shore) and still only 140 m wide. Background. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the worlds 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- SANTA ANA El Salvador 13.8530N, 89.6300W; summit elev. 2,365 m During 6-13 January, volcanic activity was moderate at Santa Ana. Seismicity was a bit over normal levels with small earthquakes occurring, which were interpreted as being associated with gas pulses. Continuous low-level emissions of steam and gas originated from the lagoon and from fumaroles within the crater. The sulfur-dioxide flux ranged between 544 and 2,300 metric tons per day. The Alert Level remained at Red, the highest level, within a 5-km radius around the volcano's summit crater. Background. Santa Ana, El Salvador's highest volcano, is a massive stratovolcano immediately W of Coatepeque caldera. Collapse of the volcano during the late Pleistocene or early Holocene produced a massive debris avalanche that swept into the Pacific, forming the Acajutla Peninsula. Reconstruction of the volcano rapidly filled the collapse scarp. The broad summit of the volcano is cut by several crescentic craters, and a series of parasitic vents and cones have formed along a 20-km-long fissure system that extends from near the town of Chalchuapa NNW of the volcano to the San Marcelino and Cerro Chino cinder cones on the SE flank. Historical activity, largely consisting of small-to-moderate explosive eruptions from both summit and flank vents, has been documented since the 16th century. The San Marcelino cinder cone on the SE flank produced a lava flow in 1722 that traveled 11 km to the E. Source: Servicio Nacional de Estudios Territoriales http://www.snet.gob.sv/ Santa Ana Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1403-02= SANTA MARMA Guatemala 14.7560N, 91.5520W; summit elev. 3,772 m During 11-13 January, several explosions occurred at Santa Marma's Santiaguito lava-dome complex, producing ash plumes that rose to ~1.5 km above the volcano (or 17,300 ft a.s.l.) and drifted SW. Lava avalanches originated from the SW edge of the Caliente dome. An explosion on the morning of 11 January generated a small pyroclastic flow that traveled down Caliente dome to the NE. INSIVUMEH reported on 16 January that a slight decrease in explosive activity was observed at the volcano during the previous month, with small-to-moderate explosions producing ash clouds that rose to ~1 km above the crater (or 15,650 ft a.s.l.). On the 16th there were reports of a small amount of ashfall in the urban area of San Felipe Retalhuleu. Background. Symmetrical, forest-covered Santa Marma 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 http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm Santa Marma Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-03= SOUFRIHRE HILLS Montserrat, West Indies 16.720N, 62.180W; summit elev. 1,052 m Activity at Soufrihre Hills remained at elevated levels during 6-13 January. Photographs revealed that the lava dome continued to grow throughout the report period over a broad sector extending from the E around to the N. Numerous small rockfalls continued from the E and NE flanks of the lava dome, adding talus in the upper reaches of the Tar River valley. The sulfur-dioxide flux averaged 724 metric tons per day. Background. The complex dominantly andesitic Soufrihre 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 Soufrihre 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/ Soufrihre Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= ST. HELENS Washington, USA 46.200N, 122.180W; summit elev. 2,549 m Growth of the new lava dome inside the crater of Mount St. Helens continued during 11-16 January, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. There were no significant changes in seismicity or deformation during the report period. Small earthquakes continued to be recorded every 2-3 minutes, with slightly larger events occurring intermittently. 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 1.470S, 78.440W; summit elev. 5,023 m Small-to-moderate explosions at Tungurahua were preceded by long-period earthquakes during 11-16 January. An explosion on 11 January produced a plume with a moderate amount of ash. The plume drifted E. Background. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuadors 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 Baqos on the N side of the volcano. Sources: Instituto Geofisico-Escuela Politecnica 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= ============================================================== 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. ==============================================================
