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SI/USGS Weekly Volcanic Activity Report 6-12 January 2010
From: Sally Kuhn Sennert - kuhns@xxxxxx
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SI/USGS Weekly Volcanic Activity Report
6-12 January 2010
6-12 January 2010
New Activity/Unrest: | Mayon, Luzon | Nyamuragira, Democratic Republic of Congo | Piton de la Fournaise, Reunion Island | Tungurahua, Ecuador | Turrialba, Costa Rica
Ongoing Activity: | Barren Island, Andaman Is | Chaitén, Southern Chile | Fuego, Guatemala | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Pacaya, Guatemala | Popocatépetl, México | Rabaul, New Britain | Redoubt, Southwestern Alaska | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Suwanose-jima, Ryukyu Islands (Japan)
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
MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m
PHIVOLCS reported that steam emissions were seen rising from Mayon's crater from 5 to 12 January during periods of clearer weather; meteorological clouds often prevented observations of the summit. Weak incandescence from the crater was occasionally seen at night. The majority of the seismic signals originated from rockfalls and detached lava fragments rolling down the flanks. Sulfur dioxide emissions fluctuated between 670 and 1,900 tonnes per day. On 12 January, PHIVOLCS noted that ground deformation measurements showed a deflationary trend compared to a 2 December 2009 survey. These measurements, along with decreased seismicity and sulfur dioxide output, prompted PHIVOLCS to lower the Alert Level to 2 on 13 January.
Geologic Summary. Beautifully symmetrical Mayon volcano, which rises to 2,462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes that average 35-40° and is capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from Strombolian to basaltic Plinian. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1,200 people and devastated several towns. Eruptions that began in February 2000 led PHIVOLCS to recommend on 23 February 2000 the evacuation of people within a radius of 7 km from the summit in the SE and within a 6 km radius for the rest of the volcano.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
NYAMURAGIRA Democratic Republic of Congo 1.408°S, 29.20°E; summit elev. 3058 m
The Washington VAAC reported a large sulfur dioxide plume in the vicinity of Nyamuragira and Nyiragongo during 10-11 January. According to a news article, lava from Nyamuragira continued to flow S and SW on 6 January, and had traveled 21 km to within 7 km of the road between Goma and Sake. On 7 January ashfall was reported in Goma, 30 km S.
Geologic Summary. Africa's most active volcano, Nyamuragira (Also spelled Nyamulagira) is a massive basaltic shield volcano N of Lake Kivu and NW of Nyiragongo volcano. Lava flows from Nyamuragira cover 1,500 sq km of the East African Rift. The 3058-m-high summit is truncated by a small 2 x 2.3 km summit caldera that has walls up to about 100 m high. About 40 historical eruptions have occurred since the mid-19th century within the summit caldera and from numerous fissures and cinder cones on the volcano's flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938. Twentieth-century flank lava flows extend more than 30 km from the summit, reaching as far as Lake Kivu.
Sources: Washington and Toulouse Volcanic Ash Advisory Centers (VAAC) personal communication,
OpEdNews http://www.opednews.com/articles/1/Congo-Volcano-Still-Active-by-Georgianne-Nienabe-100106-535.html,
Agence France-Presse http://www.google.com/hostednews/afp/article/ALeqM5iGBc8r53J8miCPRB-u9EgaFy6KGQ
OpEdNews http://www.opednews.com/articles/1/Congo-Volcano-Still-Active-by-Georgianne-Nienabe-100106-535.html,
Agence France-Presse http://www.google.com/hostednews/afp/article/ALeqM5iGBc8r53J8miCPRB-u9EgaFy6KGQ
PITON DE LA FOURNAISE Reunion Island 21.231°S, 55.713°E; summit elev. 2632 m
OVPDLF reported that during 5-7 January Piton de la Fournaise continued to erupt from a vent along a fissure high up on the SW Dolomieu crater wall. The vent produced lava fountains and flows that pooled in the bottom of the crater. On 7 January the vent closed, but the previously erupted lava continued to flow for the next few days. On 12 January, seismicity decreased and only minor gas emissions persisted.
Geologic Summary. Massive Piton de la Fournaise shield volcano on the island of Réunion is one of the world's most active volcanoes. Most historical eruptions have originated from the summit and flanks of a 400-m-high lava shield, Dolomieu, that has grown within the youngest of three large calderas. This depression is 8 km wide and is breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows within the caldera, have been documented since the 17th century. The volcano is monitored by the Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris.
Source: Observatoire Volcanologique du Piton de la Fournaise (OVPDLF) http://www.ipgp.fr/pages/03030810.php
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
The IG reported that during 5-6 January a gas-and-ash plume from Tungurahua rose to an altitude of 6.5 km (21,300 ft) a.s.l. and drifted NW. The sulfur dioxide emission rate was 3,200 tons per day, ten times the value measured during the previous months. On 7 January seismic tremor duration and amplitude increased, and signals indicative of explosions were detected. On 6 and 7 January, incandescent blocks were ejected and fell back into the crater. During 8-10 January, cloud cover often prevented observations; on 10 January a steam-and-ash plume rose to an altitude of 6.5 km (21,300 ft) a.s.l. and drifted W. Incandescence from the crater was sometimes seen at night. Ashfall up to 5 mm thick was reported in areas W and SW on 9 and 10 January. Roaring noises and vibrating glass were occasionally noted during the reporting period.
During 11-12 January, activity increased; ash plumes rose to higher altitudes and more explosions were detected. Incandescent blocks were ejected almost 1 km above the crater and 1.5 km away from the crater, onto the flanks. Gas-and-ash plumes rose to an altitude of 8 km (26,200 ft) a.s.l. and drifted in multiple directions. Ashfall was reported in areas to the NNW, W, SW, and S.
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/
TURRIALBA Costa Rica 10.025°N, 83.767°W; summit elev. 3340 m
OVSICORI-UNA reported that a phreatic eruption from Turrialba that began on 5 January was preceded by a day of increased seismicity and about 30 minutes of almost constant tremor. Two events detected about 15 minutes apart were followed by reports of ashfall as far away as 30 km. Field observations on 6 January revealed that two small vents had opened and joined together on the SE inner wall of the SW crater. Gas emission temperatures were more than 350 degrees Celsius. On 8 January seismic activity and gas emissions decreased. Observations the next day revealed that the combined vent was about 25 m wide and 80 m long. Around 60 people had evacuated from nearby farms.
Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m wide summit depression that is breached to the NE. Most activity at Turrialba originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred at Turrialba during the past 3500 years. Turrialba has been quiescent since a series of explosive eruptions during the 19th century that were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Source: Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/
Ongoing Activity
BARREN ISLAND Andaman Is 12.278°N, 93.858°E; summit elev. 354 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 11 January an ash plume from Barren Island rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 45 km S.
Geologic Summary. 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 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 historical eruptions.
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 during 16 December 2009-4 January 2010 steam-and-gas plumes from Chaitén's lava-dome complex seen on the web camera during periods of clear weather rose 1.5 km above the lava domes. Seismicity, along with occasional block-and-ash flows, indicated that the lava domes continued to grow. Based on web camera views and analyses of satellite imagery, the Buenos Aires VAAC reported that on 6 January a plume drifted 50 km ENE at an altitude of 2.1 km (7,000 ft) a.s.l. The next day an ash plume drifted SE and E at the same altitude.
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.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/,
Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html
Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
Based on analyses of satellite imagery, the Washington VAAC reported that on 6 January an ash plume from Fuego drifted 45 km SE. On 8, 11, and 12 January, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4-4.7 km (13,000-15,400 ft) a.s.l. Plumes drifted as far as 10 km in multiple directions, causing ashfall in some areas. Incandescent material was ejected to heights up to 75 m. Some explosions were accompanied by rumbling noises and shock waves that rattled structures up to 7 km away. Avalanches descended the flanks.
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.
Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/,
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that a thermal anomaly over Karymsky was detected in satellite imagery during 30-31 December 2009, 1 January and 4-7 January 2010. Seismic activity was above background levels during 1-8 January. 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
During 6-12 January, HVO reported that lava flows from Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex were seen above the pali by observers, or detected in satellite images. Lava did not enter the ocean at Waikupanaha. Incandescence was seen almost daily coming from multiple locations in Pu'u 'O'o crater. The vent in Halema'uma'u crater continued to produce a plume that drifted SW, N, and NE, dropping small amounts of ash, and occasionally fresh spatter, downwind. The NE-drifting plume resulted in poor air quality in some communities on 9 January. Incandescence originated from an active and sometimes sloshing lava surface within an opening on the deep floor of the vent cavity.
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/
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 1-8 January seismic activity from Kliuchevskoi was above background levels and lava continued to flow down the ESE flank. Strombolian activity periodically ejected material 500 m above the crater. A new lava flow seen on the NW flank likely began during 2-3 January. On 5 January two lava flows, on the ESE flank and NW flanks, were seen in satellite imagery. Satellite imagery also revealed a large daily thermal anomaly at the volcano. The Level of Concern Color Code remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
PACAYA Guatemala 14.381°N, 90.601°W; summit elev. 2552 m
On 8, 11, and 12 January, INSIVUMEH reported that white and blue fumarolic plumes from Pacaya's MacKenney cone rose up 400 m and drifted S and SW. Multiple lava flows on the S, SW, and W flanks traveled 25-200 m. Incandescence was noted at night from one of the inter-crater cones on 8 January and from MacKenney cone on 11 and 12 January.
Geologic Summary. 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 Amatitlan 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, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that on 10 and 11 January emissions of steam and gas from Popocatépetl contained minor amounts of ash.
Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED) http://www.cenapred.unam.mx/es/
RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m
RVO reported that activity from Rabaul caldera's Tavurvur cone was at a low level during 1-10 January. No emissions from the crater were observed on most days, but white steam plumes accompanied by blue plumes were occasionally seen. On 8 January, ash emissions rose less than 200 m above the cone.
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.
Source: Rabaul Volcano Observatory (RVO)
REDOUBT Southwestern Alaska 60.485°N, 152.742°W; summit elev. 3108 m
On 5 January, AVO reported that because of low levels of seismic activity from Redoubt, along with the lack of any other outward signs of progressing unrest, the Volcanic Alert Level was lowered to Normal and the Aviation Color Code was lowered to Green.
Geologic Summary. Redoubt is a 3108-m-high glacier-covered stratovolcano with a breached summit crater in Lake Clark National Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has been the most active Holocene volcano in the upper Cook Inlet. Collapse of the summit of Redoubt 10,500-13,000 years ago produced a major debris avalanche that reached Cook Inlet. Holocene activity has included the emplacement of a large debris avalanche and clay-rich lahars that dammed Lake Crescent on the south side and reached Cook Inlet about 3500 years ago. Eruptions during the past few centuries have affected only the Drift River drainage on the north. Historical eruptions have originated from a vent at the north end of the 1.8-km-wide breached summit crater. The 1989-90 eruption of Redoubt had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano.
Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 6-12 January multiple explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted SE and E. On 10 January a pilot reported that an ash plume drifted SE at an altitude of 3 km (10,000 ft) a.s.l.
Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that incandescent avalanches traveled down the SW flanks of Santa María's Santiaguito lava dome complex on 8 January. A few explosions on 11 and 12 January produced ash plumes that rose to altitudes of 3.1-3.4 km (10,200-11,200 ft) a.s.l. and drifted S, SE, and SW. Avalanches from a lava flow descended the W flank of the dome.
Geologic Summary. 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.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 1-8 January seismic activity from Shiveluch was above background levels, possibly indicating ash plumes rising to an altitude of 7.5 km (24,600 ft) a.s.l. Fumarolic activity was occasionally seen when the weather was clear. Analyses of satellite imagery revealed a large daily thermal anomaly from the lava dome and a gas-and-steam plume that drifted 40 km SW on 6 January. Ashfall was reported in Klyuchi (about 45 km SW) on 4 January. The Level of Concern Color Code remained at Orange. Based on information from KEMSD and analyses of satellite imagery, the Tokyo VAAC reported that during 6-11 January eruptions produced plumes that rose to altitudes of 4.3-6.4 km (14,000-21,000 ft) a.s.l.
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. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
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
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 31 December-8 January pyroclastic flows from the Soufrière Hills lava dome continued to travel predominantly down areas to the N including Whites Ghaut (NE), Farrells plain (N), and Tyers Ghaut (NW). Observations on 2 January showed that a 40-m-high, 150-m-wide lobe of lava had been extruded northwards onto the N summit of the dome. This lobe was the main source of rockfall and pyroclastic flow activity. On 3 and 4 January ash plumes rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted NW. Ashfall occurred in areas to the NW several times during the reporting period.
On 8 January, a large pyroclastic flow event occurred after a collapsing fountain of tephra was observed on the NE side of the volcano. Pyroclastic flows traveled NE down Whites Bottom Ghaut to the sea and down Tuitts Ghaut to within a few hundred meters of the sea. Pyroclastic flows also traveled NW down Tyers Ghaut and into the Belham Valley, W towards Plymouth, and E down the Tar River valley. The event lasted about 11 minutes and seismicity returned to background levels quickly. There was no precursory seismicity associated with the event. Ashfall was reported in inhabited areas in the NW.
Seismic signals indicated that another explosion occurred on 10 January. Pyroclastic flows descended the NE, NW, and W flanks, and ashfall was reported in areas to the NW. Another explosion later that day also caused ashfall in inhabited areas. The Hazard Level remained at 4.
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 E, was formed during an eruption about 4,000 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 (MVO) http://www.mvo.ms/
SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m
Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose-jima during 6-9 and 11 January. Plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. on 6 and 9 January and drifted E.
Geologic Summary. 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 east 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 about 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 (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
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