26 January-1 February 2011
GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m
INGEOMINAS reported that on 25 January an emerging seismic pattern from Galeras, characterized by "tornillo-type" earthquakes, was similar to patterns detected prior to past eruptions. Staff noted a strong sulfur gas odor and observed emissions from various areas of the crater that drifted N. Based on changes in seismicity and observed gas emissions, INGEOMINAS raised the Alert Level to II (Orange; "probable eruption in term of days or weeks"). Scientists again observed emissions from various areas of the crater during an overflight on 27 January, but with a slight increase in the number of vents. Gas plumes drifted NW. "Tornillo-type" earthquakes ceased on the morning of 30 January.
Geologic Summary. 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. Longterm 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.
Galeras Information from the Global Volcanism Program
KIRISHIMA Kyushu 31.931°N, 130.864°E; summit elev. 1700 m
According to the Earthquake Research Institute, an explosion on 26 January from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, prompted JMA to raise the Alert Level to 3 (on a scale of 1-5). Lightning in the ash plume was visible in video footage that same day. Based on reports from JMA, analyses of satellite imagery, and pilot observations, the Tokyo VAAC reported that during 26-27 January ash plumes rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SE. According to news articles, tephra fell as far away as 8 km on 27 January and disrupted airline and train services. Some people in Miyazaki (55 km E) voluntarily evacuated and approximately 30 people in Takaharu (15 km E) spent the night in an evacuation center. Video footage showed people clearing ash from the streets.
During an overflight on 29 January, scientists observed a new lava dome in the crater, about 50 m in diameter and incandescent in some areas. They also observed that the crater lake was gone and pyroclastic-flow deposits, 500-600 m long, were present in the SW crater. Notices issued from the Tokyo VAAC during 28-30 January stated that ash emissions were continuing. On 31 January, an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SE. A news article noted that an explosion on 1 February was heard more than 7 km away, and broke glass in buildings and cars as far as 8 km away.
Geologic Summary. Kirishima is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene volcano group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1,700-m-high Karakuni-dake being the highest. Onami-ike and Mi-ike, the two largest maars, are located SW of Karakuni-dake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Mi-ike to Ohachi, and at Shinmoe-dake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.
Sources: Earthquake Research Institute, Tokyo Volcanic Ash Advisory Center (VAAC), Japan Today, Agence France-Presse, BBC
Kirishima Information from the Global Volcanism Program
MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m
During 25-27 January, PHIVOLCS reported that one volcanic earthquake at Mayon was detected each day by the seismic network. Although cloud cover mostly prevented observation during 25-31 January, emissions of white steam were occasionally observed during cloud breaks. Incandescence from the crater was seen at night during 30-31 January. The Alert Level remained at 1 and the public was reminded not to enter the 6-km-radius Permanent Danger Zone (PDZ).
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.
Mayon Information from the Global Volcanism Program
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED noted that steam-and-gas emissions rose from Popocatépetl during 26 January-1 February. An explosion at 2056 on 31 January ejected incandescent fragments as far as 500 m down the E flank and produced an ash plume that rose 2 km and drifted E. The Washington VAAC noted that the ash plume was observed in satellite imagery on 1 February drifting more than 275 km NE.
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.
Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC)
Popocatépetl Information from the Global Volcanism Program
TENGGER CALDERA Eastern Java (Indonesia) 7.942°S, 112.95°E; summit elev. 2329 m
According to news articles, ash plumes from Tengger Caldera's Bromo cone caused flights between Perth and Bali to be disrupted during 27-28 January. Based on analysis of satellite imagery, the Darwin VAAC reported that on 28 January an ash plume rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted 370 km E and SE. On 29 January an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 93 km E. The ash cloud from the previous day was again detected and slowly drifted N. Based on analysis of imagery from multiple satellites and information from CVGHM, the VAAC reported that during 29-31 January ash plumes rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 55 km NW.
Geologic Summary. The 16-km-wide Tengger caldera in eastern Java is located at the northern end of a volcanic massif extending from Semeru volcano. The massive Tengger volcanic complex consists of five overlapping stratovolcanoes, each truncated by a caldera. The most recent is the 9 x 10 km wide Sandsea caldera, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most frequently visited and most active volcanoes. More than 50 mild-to-moderate explosive eruptions have occurred since 1804.
Tengger Caldera Information from the Global Volcanism Program
Ongoing Activity
BULUSAN Luzon 12.770°N, 124.05°E; summit elev. 1565 m
During 25-27 and 29-30 January, PHIVOLCS reported that up to five daily volcanic earthquakes at Bulusan were detected by the seismic network. Cloud cover prevented observations of the summit area. A deformation survey conducted during 25-29 January showed slight deflation relative to a December 2010 survey. 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.
Bulusan Information from the Global Volcanism Program
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 21-28 January. Seismic data showed that possible ash plumes rose to an altitude of 3.8 km (12,500 ft) a.s.l. A thermal anomaly was observed daily in satellite imagery, and ash plumes were observed drifting 65 km S and 100 km NE on 26 and 27 January, respectively. The Aviation Color Code remained at Orange.
Based on information from the Yelizovo Airport (UHPP), the Tokyo VAAC reported that an ash plume rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted NE on 1 February.
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.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
Karymsky Information from the Global Volcanism Program
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 26 January-1 February, activity continued from the summit caldera and 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 125 m below the crater floor, periodically rising or falling. Nighttime incandescence was visible from the Jaggar Museum on the NW caldera rim. A plume from the vent that drifted mostly SW deposited ash and fresh spatter nearby.
At the east rift zone, lava that broke out of the Quarry tube in a saddle between two rootless shields around 610 m elevation, continued to advance both E and W, producing scattered break-out flows. At the lowest elevation of the E branch, lava advanced along Highway 130 near Kalapana, periodically burning vegetation, and to the S towards the coast. Multiple small ocean entries were active on the W part of the Puhi-o-Kalaikini lava delta. Incandescence emanated from a spatter cone on the N portion of the Pu'u 'O'o crater floor and 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.
Kilauea Information from the Global Volcanism Program
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 21-28 January seismicity from Kizimen was high but variable, and many shallow volcanic earthquakes as well as volcanic tremor continued to be detected. Seismic data analyses suggested that ash plumes possibly rose to an altitude greater than 10 km (32,800 ft) a.s.l. on 23 and 25 January, and not more than 6 km (19,700 ft) a.s.l. on the other days. Satellite images showed a bright thermal anomaly over the volcano daily, and ash plumes that drifted more than 325 km W, S, and E. The Aviation Color Code remained at Orange.
Based on analyses of satellite imagery, the Tokyo VAAC reported that a possible eruption on 29 January produced a plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted SW. Subsequent images that day and during 30 January-1 February showed continuing ash emissions.
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), Tokyo Volcanic Ash Advisory Center (VAAC)
Kizimen Information from the Global Volcanism Program
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 26 January-1 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted SE and E. On 31 January, a pilot reported that an ash plume rose to an altitude of 2.7 km (9,000 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.
Sakura-jima Information from the Global Volcanism Program
SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m
Based on analyses of satellite imagery, the Washington VAAC reported that on 27 January small ash clouds from Sangay drifted N and quickly dissipated.
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.
Sangay Information from the Global Volcanism Program
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 21-28 January moderate seismic activity from Shiveluch was recorded, and an intense thermal anomaly over the volcano was detected in satellite imagery. Gas-and-steam emissions were visually observed during 23-26 January and an ash plume was observed rising to an altitude of 4 km (13,100 ft) a.s.l. on 26 January. Satellite imagery showed an ash plume drifting 54 km S on 26 January. The Aviation Color Code remained at Orange.
The Tokyo VAAC reported that on 31 January and 1 February possible eruptions detected in satellite imagery produced plumes that rose to altitudes of 3.4-3.7 km (11,000-12,000 ft) a.s.l. and drifted NE. Subsequent notices on both days stated that ash had dissipated.
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), Tokyo Volcanic Ash Advisory Center (VAAC)
Shiveluch Information from the Global Volcanism Program
TAAL Luzon 14.002°N, 120.993°E; summit elev. 311 m
During 25-27 and 29-30 January, PHIVOLCS reported that up to six volcanic earthquakes at Taal were detected daily by the seismic network. Field observations during 23-25 January revealed an increase in the number of steaming vents inside Main Crater and a drop in the lake level. The lake water temperature and pH values were normal. Visual observations on 27 January showed that steaming at a thermal area in the crater was weak. 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.
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