Kasatochi volcano |
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Volcano type |
stratovolcano |
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Location |
Aleutian islands, 1832 km (1138 mi) from Anchorage, 52.1693° N / 175.5113° W |
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Summit elevation |
314 m (1030 ft) |
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Last eruptions |
1760 (?), 1827 (?), 1828 (?), 1899 (?), 2008 |
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Typical eruption style |
Explosive |
Background:
From Miller and others (1998): "Kasatochi Island, like Gareloi, Bogoslof, and several other volcanoes in the western Aleutian arc, represents the emergent summit of a predominantly submarine volcano. The island consists of a single, undissected cone with a central lake-filled crater about 0.75 km in diameter. A maximum height of 314 m is on the southern crater rim; elevation of the lake is less than about 60 m. Kay (1990) reports a lava dome on the northwest side of the cone at an elevation of ~150 m.
"Coats (1956) referred to Kasatochi as one of a group of little-known volcanoes that appear to be stratovolcanoes composed of basaltic and andesitic flows and pyroclastics. The mean slope of the southern flank (about 18 degrees) is considerably less than the mean slope of the northern flank (about 45 degrees). This asymmetry of form may reflect a predominance of lava flows low on the southern flanks, or, it may be due to a higher rate of erosion by wave action from the north. Bathymetry indicated that Kasatochi is at the northern end of a 15-km-long, 6-km-wide submarine ridge that is normal to the trend of the Andreanof Islands. Water depths along the ridge are less than 90 m; if Kasatochi is constructed entirely on the ridge, the total height of the volcanic pile is only a little more than 400 m."
(from AVO's website, Kasatochi information)
Cited sources:
- Miller, T. P., McGimsey, R. G., Richter, D. H., Riehle, J. R., Nye, C. J., Yount, M. E., and Dumoulin, J. A., 1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-File Report OF 98-0582, 104 p.
- Coats, R. R., 1956, Reconnaissance geology of some western Aleutian Islands, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin B 1028-E, p. 83-100, 1 sheet, scale unknown.
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Location map showing Kasatochi volcano. Image source: Snedigar, Seth, courtesy of the Alaska Volcano Observatory / Alaska Division of Geological & Geophysical Surveys
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Kasatochi volcano: eruption news & activity updates
Aug, 08 - Sep, 14 2008
Sunday, Sep 14, 2008
It was reported that during 3-9 September seismic activity from Kasatochi was low. Vigorous steam-and-gas plumes rose above the crater and drifted up to 32 km downwind. On 4 September the Volcano Alert Level was lowered to Advisory and the Aviation Color Code to Yellow. Weak thermal anomalies were detected on 5 and 7 September.
Thursday, Aug 21, 2008
It was reported that during 13-19 August seismic activity from Kasatochi was detected by stations on Great Sitkin, about 40 km W. On 17 August, the smell of sulfur was reported in the town of Adak.
Saturday, Aug 09, 2008
Three major explosive eruptions occured at Kasatochi between approximately 2230 UTC (14:30 AKDT) on 07 August and 0500 UTC on 08 August(2100 AKDT on 07 August). ash from these explosions reached at least 45,000 ft above sea level. ash emissions became continuous following the last explosive event and have produced a continuous ash cloud extending for more than 500 miles in a counterclockwise spiral. ash from this continuous phase is likely at an altitude in excess of 35,000 ft above sea level. The possibility of larger explosive events continues.
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From: Alaska Volcano Observatory, Current Status Report,Friday, August 8, 2008
Friday, Aug 08, 2008
A subplinian or Plinian eruption is taking place at Kasatochi volcano, a remote island in the Western Aleutian chain. AVO reports that satellite data show an ash plume to an altitude of at least 35,000 ft. in the vicinity of Kasatochi Volcano 22:30 UTC (14:30 ADT) on Aug. 7th, 2008. The plume is drifting to the south-southwest.
AVO is monitoring this situation closely and has its operations room staffed 24 hours per day. More information about activity at Kasatochi Volcano can be found on the AVO web site at www.avo.alaska.edu.
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