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Smithsonian/USGS Weekly Volcanic Activity Report 20-26 April 2011
From: Sally Kuhn Sennert <kuhns@xxxxxx>
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Smithsonian/USGS Weekly Volcanic Activity Report
20-26 April 2011
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Bezymianny, Central Kamchatka (Russia) | Pagan, Mariana Islands | Ruapehu, North Island (New Zealand) | Taal, Luzon | Tungurahua, Ecuador
Ongoing Activity: | Bulusan, Luzon | Dukono, Halmahera | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Planchón-Peteroa, Central Chile-Argentina border | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia)
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
In addition to producing ashfall 45 km to the NNW on 14 April, KVERT reported that the explosive eruption from Bezymianny also generated a viscous lava flow on the SE flank. Incandescence from the lava flow was visible on 19 April. Satellite imagery showed a thermal anomaly during 15-22 April and small ash-and-gas plumes on 16 April. The Aviation Color Code remained at 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) http://www.kscnet.ru/ivs/kvert/current/bzm/index.html
PAGAN Mariana Islands 18.13°N, 145.80°E; summit elev. 570 m
On 23 April, a Northern Mariana Islands status report noted that a NOAA research vessel in the vicinity of Pagan reported night time observations of incandescence at the summit of the volcano. Eruptive activity was considered currently to be at a low level; however with the possibility that the activity may escalate the Aviation Color Code for Pagan was raised to Yellow and the Volcano Alert Level to Advisory. Recent satellite image observations were obscured by clouds.
Geologic Summary. Pagan Island, the largest and one of the most active of the Mariana Islands volcanoes, consists of two stratovolcanoes connected by a narrow isthmus. Both North and South Pagan stratovolcanoes were constructed within calderas, 7 and 4 km in diameter, respectively. The 570-m-high Mount Pagan at the NE end of the island rises above the flat floor of the caldera, which probably formed during the early Holocene. South Pagan is a 548-m-high stratovolcano with an elongated summit containing four distinct craters. Almost all of the historical eruptions of Pagan, which date back to the 17th century, have originated from North Pagan volcano. The largest eruption of Pagan during historical time took place in 1981 and prompted the evacuation of the sparsely populated island.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands, Office of the Governor, United States Geological Survey Volcano Hazards Program http://volcanoes.usgs.gov/nmi/activity/index.php
RUAPEHU North Island (New Zealand) 39.28°S, 175.57°E; summit elev. 2797 m
On 18 April, GeoNet reported that the temperature of Ruapehu's summit Crater Lake was slowly cooling and decreased to 33-34 degrees Celsius from a peak of 41 degrees in March. A general decline of activity had been noted since 4 April, including lower carbon dioxide gas flux, less seismicity, modest change in the Crater Lake water chemistry, and cessation of lake overflow accompanying the start of the cooling trend. The Aviation Colour Code remained at Yellow and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
Geologic Summary. Ruapehu, one of New Zealand's most active volcanoes, is a complex stratovolcano constructed during at least four cone-building episodes. The 110 cu km volcanic massif is elongated in a NNE-SSW direction and is surrounded by another 100 cu km ring plain of volcaniclastic debris. A single historically active vent, Crater Lake, is located in the broad summit region, but at least five other vents on the summit and flanks have been active during the Holocene. Frequent mild-to-moderate explosive eruptions have occurred in historical time from the Crater Lake vent. Lahars produced by phreatic eruptions from the summit crater lake are a hazard to a ski area on the upper flanks and to river valleys below the volcano.
Source: New Zealand GeoNet Project http://www.geonet.org.nz/
TAAL Luzon 14.002°N, 120.993°E; summit elev. 311 m
During 12-19 April, PHIVOLCS reported that between 6 and 19 daily volcanic earthquakes at Taal were detected by the seismic network. Some of the earthquakes were felt by nearby residents on the SE part of the island. The Alert Level remained at 2 (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/index.php
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
On 22 April, IG reported that in recent months the seismic network at Tungurahua detected volcano-tectonic earthquakes, indicating increased pressure in the volcano. Deformation of the NW quadrant that began in early February was slow but continuous, and then accelerated during the previous nine days. On 21 April gas-and-ash plumes caused fine ashfall in Choglontús and Cahuají (8 km SW), Pillate (8 km W), Cotaló (8 km NW), Juive (7 km NNW), and Baños (8 km N). Strombolian activity was seen at night, producing small lava fountains and incandescent blocks that rolled 1 km down the flanks. Roaring was heard and a few explosions occurred during 21-22 April. IG recommended that residents do not go within 3 km of Tungurahua's crater. On 26 April six explosions were detected and constantly-generated ash plumes rose to an altitude of 12 km (39,400 ft) a.s.l. Plumes drifted W and NW, causing steady ashfall in areas downwind. Structures vibrated in surrounding areas, including in Baños.
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/
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 on 20, 22, and 26 April ash from Bulusan was observed. PHIVOLCS reported that only diffuse steam rose from the SE vents during 20-23 April. During cloud breaks on 26 April, diffuse steam plumes from the NW and SE vents were observed rising about 50 m and drifting WSW.
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) http://www.phivolcs.dost.gov.ph/,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 21-22 April ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted less than 85 km NE and E.
Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported moderate seismic activity at Karymsky during 15-22 April. Seismic data indicated that possible ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. A thermal anomaly was detected in satellite imagery on 16, 18, and 21 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) http://www.kscnet.ru/ivs/kvert/current/bzm/index.html
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 20-26 April, HVO reported that activity at Kilauea continued from the summit caldera and from Pu'u 'O'o crater. The level of the circulating lava-pool surface in a deep pit below the Halema'uma'u crater floor periodically fluctuated. A gas plume from the vent drifted mostly SW, and deposited very small amounts of ash nearby. At Pu'u 'O'o crater, central sources continuously erupted lava within a perched lava lake that was approximately half the diameter of the crater floor. The lava level fluctuated within the lake walls and episodically overflowed the rim. During 23-24 April lava from several central sources buried most of the perched lake and covered the crater floor. During 24-25 April several large draining events were characterized by a drop in the new lava-lake surface by several meters and minor collapses of the lake's rim.
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/
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 15-22 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 plumes drifted in multiple directions as far as 254 km during 14-18 and 21 April. 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) http://www.kscnet.ru/ivs/kvert/current/bzm/index.html
PLANCHON-PETEROA Central Chile-Argentina border 35.240°S, 70.570°W; summit elev. 4107 m
Based on a SIGMET notice, the Buenos Aires VAAC reported that on 26 April an ash plume from Planchón-Peteroa rose to an altitude of 5.8 km (19,000 ft) a.s.l. and drifted E.
Geologic Summary. Planchón-Peteroa is an elongated complex volcano along the Chile-Argentina border with several overlapping calderas. Activity began in the Pleistocene with construction of the basaltic-andesite to dacitic Volcán Azufre, followed by formation of basaltic and basaltic-andesite Volcán Planchón, 6 km to the N. About 11,500 years ago, much of Azufre and part of Planchón collapsed, forming the massive Río Teno debris avalanche, which reached Chile's Central Valley. Subsequently, Volcán Planchón II was formed. The youngest volcano, andesitic and basaltic-andesite Volcá Peteroa, consists of scattered vents between Azufre and Planchón. Peteroa has been active into historical time and contains a small steaming crater lake. Historical eruptions from the Planchón-Peteroa complex have been dominantly explosive, although lava flows were erupted in 1837 and 1937.
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/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 21-25 April explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and occasionally drifted N, NE, E, and SE. On 21 and 25 April, pilots observed ash plumes that rose to altitudes of 2.7-3.4 km (9,000-11,000 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
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 15-22 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 3.2 km (10,500 ft) a.s.l. Satellite imagery showed a thermal anomaly on the lava dome during 15-18 and 20 April, and ash plumes that drifted 55 km NE on 17 April. Based on information from KEMSD and information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 22 April an eruption produced plumes that rose to altitudes of 4.3-7.3 km (14,000-24,000 ft) a.s.l. and drifted W and NW. 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) http://www.kscnet.ru/ivs/kvert/current/bzm/index.html,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
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