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Smithsonian/USGS Weekly Volcanic Activity Report 12-18 January 2011
From: "Kuhn, Sally" <KUHNS@xxxxxx>
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Smithsonian/USGS Weekly Volcanic Activity Report
12-18 January 2011
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Etna, Sicily (Italy) | Fuego, Guatemala | Kizimen, Eastern Kamchatka (Russia) | Turrialba, Costa Rica
Ongoing Activity: | Bulusan, Luzon | Colima, México | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Krakatau, Indonesia | Sakura-jima, Kyushu | San Cristóbal, Nicaragua | Sangay, Ecuador | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Suwanose-jima, Ryukyu Islands (Japan) | Taal, Luzon | Tungurahua, Ecuador
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
ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m
On the evening of 12 January Strombolian activity from a pit crater located on the lower E flank of Etna's Southeast Crater cone intensified and volcanic tremor amplitude increased. Just after 2100 lava breached the crater's E rim and formed a lava flow that traveled towards the W wall of the Valle del Bove. During the night of 12-13 January, the pit crater produced lava fountains, voluminous lava flows that descended to about 1,630 m elevation (about 4.2 km from the vent), and an ash plume that rose several kilometers. The ash plume drifted S and caused ashfall on Etna's S flank and in population centers such as Nicolosi. Scoria several centimeters in diameter fell in Rifugio Sapienza, at 1,910 m elevation. The lava fountains were sustained initially and rose 300-500 m high, then pulsated and became less vigorous, and eventually formed one single jet that rose less than 100 m. Fountaining ceased at 0055 on 13 January. Emissions of ash during 13 January were generated in part by collapses within the crater and also by sporadic explosions within the conduit. On 14 January small landslides within the pit crater produced grayish-brown plumes.
Geologic Summary. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna's summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania.
Source: Istituto Nazionale di Geofisica e Vulcanologia Sezione di Catania (INGV-CT) http://www.ct.ingv.it/index.php
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
On 10 January, INSIVUMEH reported an increase in the number and magnitude of explosions from Fuego since mid-December. During the previous three days explosions had produced ash plumes that rose 1 km above the crater and drifted 25 km mainly S and SW, and remained in the atmosphere for several hours. INSIVUMEH recommended that civil aviation authorities restrict flying within 25 km S and SW of Fuego. During 13-14 and 16-18 January explosions produced ash plumes that rose 200-500 m above the crater and drifted SW, E, and NE. Rumbling was heard and shock waves were detected. At night during 13-14 January, explosions ejected incandescent material as high as 75 m above the crater.
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.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 7-13 January a thermal anomaly over Kizimen was observed in satellite imagery. Pyroclastic flow deposits on the E flank were noted. Seismicity, recorded during 6-7 and 12 January, was high but variable, and many shallow volcanic earthquakes as well as volcanic tremor continued to be detected. Ash plumes that rose to altitudes of 6-8 km (20,000-26,000 ft) a.s.l. during 5-13 January were visually observed drifting multiple directions, and seen in satellite imagery more than 275 km W and NW. On 12 January ashfall was reported in the villages of Anavgai and Esso, 140 km NW. Seismic data during 14-15 January suggested that ash plumes rose to altitudes of 4-5 km (13,100-16,400 ft) a.s.l. Satellite images showed a bright thermal anomaly over the volcano and ash plumes drifting more than 180 km W on 15 January. The Aviation Color Code level was lowered to Orange.
Geologic Summary. Kizimen is an isolated, conical stratovolcano that is morphologically similar to Mount St. Helens prior to its 1980 eruption. The summit of Kizimen consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2,376-m-high Kizimen was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of longterm lava-dome growth have occurred. The latest eruptive cycle began about 3,000 years ago with a large explosion and was followed by lava-dome growth lasting intermittently about 1,000 years. An explosive eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. A single explosive eruption, during 1927-28, has been recorded in historical time.
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/FR/messages.html
TURRIALBA Costa Rica 10.025°N, 83.767°W; summit elev. 3340 m
According to news articles, people near Turrialba reported minor ashfall 2 km SE, rumbling noises, and a strong sulfur odor on 14 January. A few people were evacuated. OVSICORI-UNA noted that a blue and white gas plume rose from Turrialba the next day.
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.
Sources: Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/,
La Nacion http://www.nacion.com/2011-01-14/Sucesos/UltimaHora/Sucesos2652814.aspx
Ongoing Activity
BULUSAN Luzon 12.770°N, 124.05°E; summit elev. 1565 m
During 11-17 January, PHIVOLCS reported that up to 2 daily volcanic earthquakes at Bulusan were detected by the seismic network. Cloud cover prevented observations of the summit area. An explosion on 18 January was accompanied by a rumbling sound audible in Monbon, a barangay (neighborhood) in the municipality of Irosin, to the S. Cloud cover prevented observations of the crater. Trace amounts of ashfall were observed in Monbon. The Alert Level remained at 1 (on a scale of 0-5).
Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed within the 11-km-diameter dacitic Irosin caldera, which was formed more than 36,000 years ago. A broad, flat moat is located below the prominent SW caldera rim; the NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit of Bulusan volcano is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
COLIMA México 19.514°N, 103.62°W; summit elev. 3850 m
According to news articles from 11 and 12 January, although incandescent landslides from Colima's lava dome had increased during the last days of 2010 into early 2011, the activity was still considered to be within normal parameters. Landslides occurred on the W, S, and N flanks, producing "dust plumes" observed from multiple municipalities. The lava dome that began growing in February 2007 was about 60 m high and had a volume of 2.6 million cubic meters.
Geologic Summary. 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 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: Noticieros Televisa http://noticierostelevisa.esmas.com/nacional/246635/aumentan-derrumbes-volcan-colima,
El Universal http://www.eluniversal.com.mx/notas/737154.html
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that moderate seismic activity was detected at Karymsky during 7-13 January. A thermal anomaly was observed in satellite imagery on 9 January; cloud cover obscured views on the other days. Seismic data showed that possible ash plumes rose to an altitude of 4.2 km (13,800 ft) a.s.l. during 10-12 January. The Aviation Color Code level 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 12-18 January, HVO reported that activity at Kilauea continued from the summit caldera and the east rift zone. At the summit caldera, the level of the lava-pool surface in the deep pit within Halema'uma'u crater circulated and remained mostly stable at approximately 120 m below the crater floor, periodically rising several meters higher. Nighttime incandescence was visible from the Jaggar Museum on the NW caldera rim. A plume from the vent that drifted S, NE, and N deposited ash and fresh spatter nearby.
At the east rift zone, lava that broke out of the Quarry tube at a saddle between two rootless shields around 610 m elevation, continued to advance in two branches, E and W. At the lowest elevation of the E branch lava advanced along Highway 130 near Kalapana, set a kipuka on fire, and destroyed a structure. One part of the W branch entered the ocean at Ki, about 2 km SW of the end of Highway 130. A spatter cone on the N portion of the Pu'u 'O'o crater floor fed lava flows and incandescence emanated from the fuming vent in the E wall of the crater.
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/
KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m
Based on information from CVGHM, the Darwin VAAC reported that on 12 January an eruption plume from Anak Krakatau rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE. Meteorological clouds prevented observations of the area from satellite. On 15 January, a pilot observed a plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 18-28 km E.
Geologic Summary. Renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927.
Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 13 and 16-18 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted SE. On 17 January, a pilot reported that an ash plume rose to altitudes of 1.2-2.1 km (4,000-7,000 ft) a.s.l. and drifted SE.
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/FR/messages.html
SAN CRISTOBAL Nicaragua 12.702°N, 87.004°W; summit elev. 1745 m
Based on a METAR weather notice, the Washington VAAC reported a possible ash plume on 13 January. Satellite imagery showed a narrow and diffuse plume drifting SW.
Geologic Summary. 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, San Cristóbal itself (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 west 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: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m
Based on a pilot observation, the Washington VAAC reported that on 12 January an ash plume from Sangay rose to an altitude of 6.7 km (22,000 ft) a.s.l. and possibly drifted more than 45 km SW. A thermal anomaly was detected in satellite imagery.
Geologic Summary. The isolated Sangay volcano, located E of the Andean crest, is the southernmost of Ecuador's volcanoes, and its most active. It has been in frequent eruption for the past several centuries. The steep-sided, 5,230-m-high glacier-covered volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the E, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. Sangay towers above the tropical jungle on the E side; on the other sides flat plains of ash from the volcano have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The more or less constant eruptive activity has caused frequent changes to the morphology of the summit crater complex.
Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that moderate seismic activity from Shiveluch was detected during 7-13 January. A bright thermal anomaly over the lava dome was observed in satellite imagery during 7-11 January. Visual observations during 7-9 and 13 January, when the weather did not obscure the volcano, showed steam-and-gas activity. The Aviation Color Code level remained at Orange.
Based on information from KEMSD, the Tokyo VAAC reported that on 18 January an eruption produced a plume that rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted W.
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/FR/messages.html
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 7-14 January activity from the Soufrière Hills lava dome was at a low level. Helicopter observations revealed fresh pyroclastic-flow deposits less than 1 km long on the E side of the lava dome. A small pyroclastic flow occurred at the head of the Tar River valley to the E on 6 January. The Hazard Level remained at 3.
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 12-13 and 15 January. A plume rose to an altitude of 1.2 km (4,000 ft) a.s.l. and drifted SE on 13 January.
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
TAAL Luzon 14.002°N, 120.993°E; summit elev. 311 m
PHIVOLCS reported that a deformation survey of Taal conducted in December 2010 showed slight inflation as compared to a survey conducted in September 2010. Field observations on 10 January revealed no significant changes. Weak steaming from a thermal area inside the main crater was noted and the lake temperature and color were normal. During 15-16 January 10 volcanic earthquakes were detected; two earthquakes were felt by residents in barangay (neighborhood) Pira-piraso, on the N side of the island. On 17 January three volcanic earthquakes were detected and on 18 January only one was reported. The Alert Level remained at 1 (on a scale of 0-5).
Geologic Summary. Taal volcano is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. In contrast to Mayon volcano, Taal is not topographically prominent, but its prehistorical eruptions have greatly changed the topography of SW Luzon. The 15 x 20 km Taal caldera is largely filled by Lake Taal, whose 267 sq km surface lies 700 m below the S caldera rim and only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is a complex volcano composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that has grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions of Taal have caused many fatalities.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
The IG reported that during 5-17 January activity at Tungurahua continued to decrease and ash was absent from plumes. At night during 11-12 January incandescence from the crater was observed. Although cloudy weather often prevented observations during 11-18 January, weak steam plumes were occasionally observed rising from the crater.
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/
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