Smithsonian/USGS Weekly Volcanic Activity Report (29 December

Reports of increased volcanic activity at Barren Island and Narcondam volcanoes during the week of 2 January were found to be false. Professor Chandrasekharam from the Indian Institute of Technology reported that as of 4 January no unusual volcanic activity was occurring at these volcanic islands. Newspaper reports of active "mud volcanoes" in the Andaman Islands caused a great deal of concern and confusion.

Backgrounds. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of a volcano that rises from a depth of about 2,250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the W, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. The morphology of a fresh pyroclastic cone that was constructed in the center of the caldera has varied during the course of historical eruptions. Lava flows fill much of the caldera floor and have reached the sea along the western coast during eruptions in the 19th century and more recently in 1991 and 1995.

Narcondum volcano, an island possession of India in the Andaman Sea, is part of a volcanic arc that continues northward from Sumatra to Burma (Myanmar). The small 3 x 4 km wide conical island, located about 130 km E of North Andaman Island, rises to 710 m, but its base lies an additional 1,000 m beneath the sea. The island is densely vegetated, bounded by cliffs on the southern side, and capped by three peaks. No evidence of historical volcanism is present, although the summit region is less densely vegetated and volcanism at the andesitic volcano is considered to have continued into the Holocene. The island's name means "pit of hell," although the name could have been mistakenly transferred from the historically active Barren Island volcano, 140 km to the SSW.

Source: Professor D Chandrasekharam, Indian Institute of Technology http://www.geos.iitb.ac.in/dchandra

Barren Island Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0600-01= Narcondam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0600-001

VENIAMINOF Alaska Peninsula, USA 56.17°N, 159.38°W; summit elev. 2,507 m; All times are local (= UTC - 9 hours)

AVO raised the Concern Color Code at Veniaminof from Green to Yellow on 4 January because around that time several small ash emissions from the volcano's intracaldera cone were observed on the Internet camera in Perryville . Ash emissions were visible starting around 0938, but may have been obscured by meteorological clouds in previous images. The discrete ash emissions were small, rose hundreds of meters above the cone, and dissipated as they drifted E. Minor ash fall was probably confined to the summit caldera. Very weak seismic tremor was recorded beginning on 1 January, and increased slightly over the next 2 days. These seismic signals were similar to those recorded during steam-and-ash emissions in April to October, 2004. However, there were no indications from seismic data that events significantly larger than those observed around 4 January are imminent. AVO expects that steam-and-ash emissions may continue intermittently and could pose a hazard to people and low-flying aircraft in the vicinity of the active cone.

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-

According to the Washington VAAC, on 30 December an ash plume was visible at Colima on satellite imagery. The plume rose to ~7 km a.s.l. and extended as far as ~37 km E. Late on 30 December a second steam-and-ash plume rose to ~7 km a.s.l. and extended E. On 1 January an eruption produced a steam-and-ash plume that reached ~5.5 km a.s.l. and extended ~33 km N.

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 Volcán de Colima on the S. Volcán de Colima (also known as Volcán 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 repetitively 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 have mostly originated from Colima's summit crater. The current eruptive episode began in November 1998 and has included summit lava-dome growth, block lava flows, pyroclastic flows, and intermittent explosive activity.

Source: 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=

On 28 December, an observed eruption at Karymsky produced a plume composed primarily of gas and steam, but with some ash, that rose to ~1 km above the crater. Thermal anomalies were also visible on satellite imagery on 27 and 28 December. On 30 December the Tokyo VAAC reported that a plume was present up to ~8 km a.s.l. and extending SW. Karymsky remained at Concern Color Code Orange .

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.

Sources: Kamchatkan Volcanic Eruption Response Team via the Alaska Volcano Observatory http://www.avo.alaska.edu/avo4/updates/kvertweekly.htm, Tokyo Volcanic Ash Advisory Center http://www.jma.go.jp/JMA_HP/jma/jma-eng/jma-center/vaac/index.html Karymsky Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13=

During 3-4 January, surface lava flows were visible at Kilauea along the PKK lava flow on the Pulama pali fault scarp and on the coast. Summit seismicity remained low on both days with only a few long-period earthquakes recorded per day, and weak-to-absent background tremor. At Pu`u `O`o cone tremor remained at moderate levels, with periods of slight inflation and deflation recorded.

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

On 29 December the Darwin VAAC, based on information from RVO, reported that Manam was at Alert Level 2, a reduction from the previous Alert Level 3. During 1-4 January, Manam produced variable emissions.

Background. The 10-km-wide island of Manam is one of mainland 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: Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/info/vaac/advisories.shtml Manam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02=

SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m

During 23-28 December, seismicity decreased slightly at Shiveluch but remained above background levels. Seismicity indicated that possible ash-and-gas explosions occurred on 26 and 27 December and plumes may have risen as high as ~4 km a.s.l. Observed explosions also occurred on 26 and 27 December that produced gas-and-ash explosions to ~2 km above the lava dome. Possible weak gas-and-ash explosions accompanied by hot avalanches occurred throughout the report period. On 28 December a gas-and-steam plume extended as far as 50 km E. Shiveluch remained at Concern Color Code Orange .

Background. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large horseshoe-shaped caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. During the 1990s, intermittent explosive eruptions took place from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.

Source: Kamchatkan Volcanic Eruption Response Team via the Alaska Volcano Observatory http://www.avo.alaska.edu/avo4/updates/kvertweekly.htm Shiveluch Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1000-27=

SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m

During 24-31 December, one long-period, six hybrid, and two volcano-tectonic earthquakes were recorded at Soufrière Hills. The sulfur-dioxide flux averaged 410 metric tons per day and ranged between 300 and 550 metric tons per day.

Background. The complex 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. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but the first well-documented historical eruption on Montserrat did not take place until 1995. Long-term small-to-moderate ash eruptions were 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 severe 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/gvp/world/volcano.cfm?vnum=1600-05=

Seismic unrest continued at Spurr during 26-31 December, with an average of 5-6 earthquakes recorded per day. A distinct increase in seismicity occurred on 26 December when 25 earthquakes were recorded. Spurr remained at Concern Color Code Yellow .

Background. The 3,374-m-high summit of Mount Spurr, the highest volcano of the Aleutain arc, is a large lava dome constructed at the center of a roughly 5-km-wide horseshoe-shaped caldera that is open to the S. The volcano lies 130 km W of Anchorage, NE of Chakachamna Lake. The caldera was formed by a late-Pleistocene or early Holocene debris avalanche and associated pyroclastic flows that destroyed an ancestral Spurr volcano. The debris avalanche traveled more than 25 km to the SE, and the resulting deposit contains blocks as large as 100 m in diameter. Several ice-carved post-caldera cones or lava domes lie in the center of the caldera. The youngest vent, 2,309-m-high Crater Peak, formed at the southern breached end of the caldera and has been the source of about 40 identified Holocene tephra layers. Spurr's two historical eruptions, from Crater Peak in 1953 and 1992, deposited ash on the city of Anchorage.

Source: Alaska Volcano Observatory http://www.avo.alaska.edu/avo4/updates/updates.htm Spurr Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-04-

Lava-dome growth continued at St. Helens during 28 December to 4 January. Observations on 3-4 January indicated that the new dome, with the exception of the northern-most portion, was becoming heavily fractured and faulted. GPS data showed that expansion of the rear part of the dome had slowed to a rate of only a few meters per day. Seismicity decreased dramatically during 29-30 December, reaching the lowest levels recorded since dome building began. This lull continued through 4 January. 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/gvp/world/volcano.cfm?vnum=1201-05-

On 29 December, the Tokyo VAAC reported an eruption at Suwanose-jima that produced an ash plume to ~1.2 km a.s.l. Eruptions were also reported on 1 and 4 January, but no plumes were visible on satellite imagery.

Background. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for around 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884.

Source: Tokyo Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html Suwanose-jima Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0802-03=

On 2 January, Tungurahua remained at a low level of activity with weak gas-and-steam emissions containing only a moderate amount of ash. Two small explosions were recorded.

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.

Source: Instituto Geofisico-Escuela Poltecnica Nacional http://www.igepn.edu.ec/vulcanologia/tungurahua/actividad/informet.htm Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08=

Department of Geology and Geological Engineering University of North Dakota Grand Forks, ND

This is THE authoritative list of worldwide volcanic activity.

As I've attempted to point out many times, reports of volcanic activity at Barren Island were bogus (even the BBC got fooled.)

Since the Dec. 26 earthquake the only actual volcano in the world to new (and minor) activity is Veniaminof in Alaska, many thousands of miles from the quake. And normally every week or every other week there's one new activity report on the list anyway.

You can also get this list e-mailed to you on a listserv; you can sign up at the Smithsonian site.

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