Sunday, February 26, 2012

[ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 15-21 February 2012

Smithsonian/USGS Weekly Volcanic Activity Report 15-21 February 2012
From: "Faulk, Elisabeth" <>

Smithsonian/USGS Weekly Volcanic Activity Report

15-21 February 2012

Elisabeth Faulk - Weekly Report Editor


New Activity/Unrest: | Cleveland, Chuginadak Island | Kanaga, Andreanof Islands | Reventador, Ecuador | Tinakula, Santa Cruz Islands (SW Pacific) | Tungurahua, Ecuador | Turrialba, Costa Rica

Ongoing Activity: | Bezymianny, Central Kamchatka (Russia) | Hierro, Canary Islands (Spain) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Popocatépetl, México | Puyehue-Cordón Caulle, Central Chile | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia)

This page is updated on Wednesdays. Please see the GVP Home Page for news of the latest significant activity.

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

CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m

AVO reported that during 15-18 and 20-21 February no observations of elevated surface temperatures or ash emissions from Cleveland were noted. On 17 February, AVO reported that partly-cloudy satellite observations over the past week revealed that the lava dome had grown to about 60 m in diameter. On 19 February an elevated surface temperature was detected in satellite images. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange. No current seismic information was available because Cleveland does not have a real-time seismic network.

Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

Source: Alaska Volcano Observatory (AVO)

KANAGA Andreanof Islands 51.923°N, 177.168°W; summit elev. 1307 m

AVO reported possible explosive activity at Kanaga on 18 February. Volcanic tremor detected during 0623-0627 was followed by about an hour of numerous small seismic events. Satellite images showed a detached ash plume, 8 km in length, which drifted 39 km NE. AVO raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory on 18 February. Elevated seismic activity continued on 19 February, and photographs taken by a local observer showed a small steam plume. Clouds prevented views of the volcano during 19-21 February.

Geologic Summary. Symmetrical Kanaga stratovolcano is situated within the Kanaton caldera at the northern tip of Kanaga Island. The rim of Kanaton caldera forms a 760-m-high arcuate ridge south and east of Kanaga; a lake occupies part of the SE caldera floor. The volume of subaerial dacitic tuff is smaller than would typically be associated with caldera collapse, and deposits of a massive submarine debris avalanche associated with edifice collapse extend nearly 30 km to the NNW. Several fresh lava flows from historical or late prehistorical time descend the flanks of Kanaga, in some cases to the sea. Historical eruptions, most of which are poorly documented, have been recorded since 1763. Kanaga is also noted petrologically for ultramafic inclusions within an outcrop of alkaline basalt SW of the volcano. Fumarolic activity occurs in a circular, 200-m-wide, 60-m-deep summit crater and produces vapor plumes sometimes seen on clear days from Adak, 50 km to the east.

Source: Alaska Volcano Observatory (AVO)

REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m

IG reported that activity continued at Reventador during 15-21 February. Satellite images showed a thermal anomaly on the NE flank from the lava flow that was observed on 12 February. Clouds prevented views on 17, 19, and 21 February. Based on analysis of satellite imagery, the Washington VAAC reported an ash plume that drifted 19 km SE on 16 February. IG observed an ash plume that rose 100 m above the crater on 18 February.

Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC)

TINAKULA Santa Cruz Islands (SW Pacific) 10.38°S, 165.80°E; summit elev. 851 m

According to NASA's Earth Observatory, thermal anomalies from Tinakula were detected in satellite data during 13-14 February and a gas plume with possible ash content rose from the volcano on 14 February.

Geologic Summary. The small 3.5-km-wide island of Tinakula is the exposed summit of a massive stratovolcano that rises 3-4 km from the sea floor at the NW end of the Santa Cruz islands. Tinakula resembles Stromboli volcano in containing a breached summit crater that extends from the 851-m-high summit to below sea level. Landslides enlarged this scarp in 1965, creating an embayment on the NW coast. The satellitic cone of Mendana is located on the SE side. The dominantly andesitic Tinakula volcano has frequently been observed in eruption since the era of Spanish exploration began in 1595. In about 1840, an explosive eruption apparently produced pyroclastic flows that swept all sides of the island, killing its inhabitants. Frequent historical eruptions have originated from a cone constructed within the large breached crater. These have left the upper flanks of the volcano and the steep apron of lava flows and volcaniclastic debris within the breach unvegetated.

Source: NASA Earth Observatory

TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m

IG reported continuing activity at Tungurahua during 15-21 February. Increased seismicity and constant harmonic tremor were detected on 16 February. Based on information from the Guayaquil MWO and IG, the Washington VAAC reported that during 17-18 February emissions rose to an altitude of 6 km (19, 500 ft) a.s.l. IG also noted that a steam plume with small amounts of ash drifted WSW on 19 February and W on 21 February.

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.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC)

TURRIALBA Costa Rica 10.025°N, 83.767°W; summit elev. 3340 m

OVSICORI-UNA reported that while conducting field work at Turrialba during 2-3 February, scientists observed incandescence with temperatures between 600-700 degrees Celsius from the three main vents of the W crater. The vents are comprised of the 2010 vent (on the SW rim), the 2011 vent (on the N side at the bottom of the crater), and the 2012 vent (on the SE flank).

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)

Ongoing Activity

BEZYMIANNY Central Kamchatka (Russia) 55.978°N, 160.587°E; summit elev. 2882 m

KVERT reported that seismic activity increased at Bezymianny on 12 February and remained elevated through 19 February. The size and brightness of a thermal anomaly observed in satellite images both increased during this interval. Blocks possibly extruded from the top of the lava dome. KVERT raised the Aviation Color Code to Orange on 19 February.

Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

HIERRO Canary Islands (Spain) 27.73°N, 18.03°W; summit elev. 1500 m

Instituto Geográfico Nacional (IGN) reported that during 15-16 February the amplitude of the tremor showed very low values, and after 17 February the tremor signal could not be clearly recognized in the seismic records. Very weak and intermittent discoloration was observed in the emission area. By the end of the reported period, there was no clear instrumental evidence of continuous eruptive activity.

One hundred and thirty-five seismic events were located, most of them in the central part of the island, with offshore events extending to the S. Depths of the hypocenters varied between 6 and 20 km and magnitudes between 0.2 and 2.5 (91 events with a magnitude equal or greater than 1). One event was felt by residents with a maximum intensity value of II (EMS-98). GPS data pointed to a slight uplift in some stations located at the N of the island.

Geologic Summary. The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive Hierro shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago. The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts oriented NW, NE, and south at 120 degree angles form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an historical eruption in 1793.

Source: Instituto Geográfico Nacional (IGN)

KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m

KVERT reported that seismic activity continued at a moderate level at Karymsky during 10-17 February and indicated that possible ash plumes rose to an altitude of 4.6 km (15,000 ft) a.s.l. Satellite imagery showed a thermal anomaly at the volcano all week. According to visual observations from Koryaksky volcano, gas-and-steam activity occurred at Karymsky on 12 February. The Aviation 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)

KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m

During 15-21 February, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Strong incandescence was visible from the collapsed cone on the NE edge and weaker from a cone on the SE edge during 15-18 and 20 February. A web camera recorded strong incandescence above the pali during 15-16 February. Incandescence also emanated from two sources on the E flank on 19 and 21 February.

Web camera views and satellite images indicated that lava flows remained active within the abandoned Royal Gardens subdivision more than 6.5 km SE of Pu'u 'O'o during 15-21 February. The flows advanced down the pali along the E side of the December 2011 flows during the week and on 21 February advanced to the kipuka on the E. On 17 February a second smaller branch appeared on the W side of the December 2011 flows. Ground-based observers reported active lava flows at the top of the pali during 15-21 February.

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)

KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m

KVERT reported moderate seismic activity at Kizimen during 10-17 February and a large thermal anomaly that was detected daily in satellite images. Video and satellite observations indicated both continued effusion of a large lava flow on the E flank and accompanying hot avalanches. Video data showed strong gas-and-steam activity all week. The Aviation Color Code remained at 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m

CENAPRED reported that during 15-21 February steam-and-gas emissions rose from Popocatépetl; some of the emissions contained small amounts of ash on 16 and 20-21 February. Crater incandescence was observed during 16 and 19-21 February.

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)

PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m

Based on seismicity detected during 15-21 February, OVDAS-SERNAGEOMIN reported that the eruption from the Cordón Caulle rift  zone, part of the Puyehue-Cordón Caulle volcanic complex, continued at a low level. During 14-16 and 20-21 February plumes observed with a web camera rose 1 km above the crater; clouds prevented views during 17-19 February. Satellite images showed ash plumes drifting 12-180 km NE, ENE, SE, and ESE during 14-15 and 18-21 February. Clouds prevented views from satellite during 16-17 February. Crater incandescence was observed during 14-15 February. The Alert Level remained at Red.

Geologic Summary. The Puyehue-Cordón Caulle volcanic complex (PCCVC) is a large NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end by the Cordón Caulle fissure complex. The Pleistocene Mencheca volcano with Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue volcano is the most geochemically diverse of the PCCVC. The flat-topped, 2236-m-high Puyehue volcano was constructed above a 5-km-wide caldera and is capped by a 2.4-km-wide summit caldera of Holocene age. Lava flows and domes of mostly rhyolitic composition are found on the eastern flank of Puyehue. Historical eruptions originally attributed to Puyehue, including major eruptions in 1921-22 and 1960, are now known to be from the Cordón Caulle rift zone. The Cordón Caulle geothermal area, occupying a 6 x 13 km wide volcano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone.

Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)

SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m

Based on information from JMA, the Tokyo VAAC reported that during 15-16 and 18-21 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NE, E, and 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)

SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m

KVERT reported that low levels of seismic activity were detected at Shiveluch during 10-17 February. Satellite imagery showed a weak thermal anomaly during 10-11 and 15-16 February. Ground-based observers noted that a viscous lava flow continued to effuse in the crater that was formed during a 2010 eruption. Moderate fumarolic activity at the lava dome was observed on 14 February; clouds prevented observations on the other days of the week. The Aviation Color Code remained at Orange.

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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)


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