Monday, April 18, 2011

[ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 6-12 April 2011

Smithsonian/USGS Weekly Volcanic Activity Report 6-12 April 2011
From: "Kuhn, Sally" <>

Smithsonian/USGS Weekly Volcanic Activity Report

6-12 April 2011

Sally Kuhn Sennert - Weekly Report Editor


New Activity/Unrest: | Bezymianny, Central Kamchatka (Russia) | Etna, Sicily (Italy) | Kilauea, Hawaii (USA) | Taal, Luzon

Ongoing Activity: | Bulusan, Luzon | Karymsky, Eastern Kamchatka (Russia) | Kizimen, Eastern Kamchatka (Russia) | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | 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

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

KVERT reported that during 1-11 April seismicity from Bezymianny increased. Gas-and-steam activity was observed during 1-2 April; clouds obscured views on the other days. A thermal anomaly over the volcano observed in satellite imagery was weak during 1-3 and 6 April, then increased in size and became more intense. The Aviation Color Code was raised to Orange.

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)

ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m

INGV-CT reported that from 29 March through the first few days of April, a series of gas-and-ash emissions, rarely with minor incandescent material, rose from the pit crater on the E flank of Etna's SE Crater cone. On 8 April small Strombolian explosions occurred from two vents located in the W portion of the crater floor; ejecta were confined to the crater depression. On 9 April seismicity from the Strombolian activity increased throughout the day. In the afternoon, explosive activity commenced from two vents before lava flows covered the crater floor. Later that evening incandescent blocks appeared within a breach in the E rim of the crater, followed by a small overflow of lava. The lava flow advanced from the base of the SE Crater cone toward the W headwall of the Valle del Bove, as far as 1 km. At the same time small but frequent Strombolian explosions continued within the crater.

During the night of 9-10 April, the Strombolian activity within the pit crater gradually increased, as well as volcanic tremor amplitude. The lava flow continued to advance. On 10 April, activity and tremor amplitude significantly increased and culminated with vigorous lava fountaining. An ash-and-gas plume drifted SE, causing ashfall in areas downwind. The lava-flow emission rate also increased dramatically. A second lava flow covered the first and traveled down into the Valle del Bove, essentially following the same path as the lava flows of 12-13 January and 18 February. The lava flow encountered thick snow cover, leading to violent explosive interactions that generated pyroclastic flows, and resulted in spectacular vapor-and-ash plumes. The eruption declined rapidly after about 1500; no activity was observed later than the afternoon.

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)

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

HVO reported that lava in the deep pit within Kilauea's Halema'uma'u crater was visible on 5 April and rose, fell, and circulated within the pit during 6-12 April. At Pu'u 'O'o crater, the level of the lava lake fluctuated, and was fed from a source in the central portion of the lake. During 5-8 April a gas plume from the vent deposited very small amounts of ash nearby, derived from rockfalls and occasional lake spatter.

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)

TAAL Luzon 14.002°N, 120.993°E; summit elev. 311 m

PHIVOLCS reported that field observations of Taal conducted at the E sector inside the main crater lake on 5 April 2011 showed that steaming at the thermal area was weak. The water level had receded 3 mm and the water temperature slightly increased from 30 to 30.5 degrees Celsius. Since the previous measurement on 29 March, the pH value increased indicating that the water had become slightly less acidic. Gas measurements conducted last January, February, and March yielded carbon dioxide emission values (in tonnes per day) of 2,250, 1,875, and 4,670, respectively.

On 9 April PHIVOLCS noted that after 31 March the number of earthquakes gradually rose and the depths become more shallow (1-4 km). Steaming at the N and NE sides of the main crater occasionally intensified and was occasionally accompanied by hissing sounds. The Alert Level was raised to 2 (on a scale of 0-5) because of increased seismicity and carbon dioxide emissions. PHIVOLCS warned tourists and residents to avoid Volcano Island. According to news articles, about 100 families had volunteered to evacuate; about 7,000 people remained.

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.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS),

Philippine Daily Inquirer 327.html

Ongoing Activity

BULUSAN Luzon 12.770°N, 124.05°E; summit elev. 1565 m

Based on notices from the Manila airport (RPLL), the Tokyo VAAC reported that ash from Bulusan was observed during 7-8 and 11 April. Plumes drifted W on 7 April, and NW and SW on 11 April. PHIVOLCS reported that during breaks in the clouds on 7 April steam plumes were observed rising from the SE and NW thermal vents.

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.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS),

Tokyo Volcanic Ash Advisory Center (VAAC)

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

KVERT reported moderate seismic activity at Karymsky during 1-7 April. Seismic data indicated that possible ash plumes rose to an altitude of 4.5 km (14,800 ft) a.s.l. A thermal anomaly was detected in satellite imagery on 2 and 4 April and ash-and-gas plumes drifted in multiple directions as far as 48 km during 1-2 and 4 April. 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)

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

KVERT reported that during 1-7 April seismicity from Kizimen was high, with many shallow volcanic earthquakes and volcanic tremor continuing to be detected. Satellite images showed a large bright thermal anomaly daily on the volcano. Ash and gas-and-steam plumes drifted multiple directions as far as 259 km. The Aviation Color Code remained at Orange.

Based on analyses of satellite imagery, the Tokyo VAAC reported that a possible eruption on 7 April produced a plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted S. Subsequent images that day and on 8 April showed continuing ash emissions. Another possible eruption on 10 April produced a plume that rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted SE.

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)

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

On 6, 9, and 12 April, pilots observed ash plumes from Sakura-jima that rose to altitudes of 2.7-3 km (9,000-10,000 ft) a.s.l. Plumes on 9 April drifted SE and plumes on 12 April drifted S. Based on information from JMA, the Tokyo VAAC reported that during 7-12 April explosions produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and occasionally drifted NE, E, SE, and S.

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 during 1-7 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 7.5 km (24,600 ft) a.s.l. Ground-based observations during 1-2 April indicated that gas-and-steam plumes containing ash rose to an altitude of 2.7 km (8,800 ft) a.s.l. A thermal anomaly on the lava dome was observed in satellite imagery those same two days. Ash plumes drifted in different directions as far as 187 km during 1-3 and 5 April. The Tokyo VAAC reported that on 7 April a possible eruption detected in satellite imagery produced a plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. Subsequent notices that day stated that ash continued to be detected, and then dissipated. 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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT),

Tokyo Volcanic Ash Advisory Center (VAAC)

SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m

Based on information from JMA, the Tokyo VAAC reported that explosions from Suwanose-jima on 12 April produced a plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l.

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)


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