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Little Sitkin


Facts

  • Official Name: Little Sitkin Island
  • Seismically Monitored: Yes
  • Color Code: GREEN
  • Alert Level: NORMAL
  • Elevation: 1188m (3897ft)
  • Latitude: 51.9531
  • Longitude: 178.5356
  • Smithsonian VNum: 311050
  • Pronunciation:
  • Nearby Towns:
    • Shemya Station 194 mi (312 km) NW
    • Adak 206 mi (332 km) SE
    • Attu Station 233 mi (375 km) NW
    • Atka 309 mi (497 km) NE
    • Nikolski 534 mi (860 km) NE

    Distance from Anchorage: 1343 mi (2161 km)

  • Subfeatures:
    • Caldera One
    • Caldera Two

Description

From Miller and others (1998) [1] : "The active stratovolcano on Little Sitkin Island occurs within the eroded remnants of a nested double caldera of probable late Pleistocene age. The older caldera (Caldera One) is about 4.8 km in diameter and is centered slightly northeast of the island's midpoint. The caldera formed at the site of a large stratovolcano, the remnants of which are the oldest rocks exposed on the island (unit Qtw [2] ).
"A second stratovolcano was constructed almost entirely of lava flows (unit Qd) within Caldera One and attained a height of about 900 m. A cataclysmic eruption, possibly in early post-glacial time, resulted in the formation of a second, smaller caldera (Caldera Two) that partially destroyed this cone. Caldera Two is elliptical in outline and measures 2.7 by 4 km; the inferred eastern and southern margins are coincident with those of Caldera One. Field relations suggest that the northern boundary of Caldera Two is a hinge along which a large block, comprising most of the Caldera One stratovolcano, was tilted southward during the caldera eruption. The highest peak on the island is on the post-caldera remnant of the second cone.
"A deposit of partly welded tuff up to 100 m thick (unit Qp) extends from the remnant cone northwest across the Caldera Two boundary fault, to slightly beyond the inferred location of the Caldera One boundary fault. The deposit is thought to have been emplaced by one of more pyroclastic flows, possibly associated with formation of Caldera Two [2] .
"Post-Caldera Two deposits are mainly lava flows (units Qls, Qlp, and Qlw). Two relatively recent aa flows have well developed levees; one originated from the breached central crater of Little Sitkin volcano, and the other from a fissure along the western trace of the Caldera One boundary fault [2] ."

Name Origin

The island of Little Sitkin was named "O[strov] Malyy Sitkhin," meaning "little Sitkin island" on the 1848 Russian Hydrographic Department Chart 1400. The name "Sitkin" may possibly be from the Unangam Tunuu word "sixtan," which, according to R.H. Geoghegan, means "from beneath or from under" (Orth, 1971). Bergsland (1994) translates this word as "dung" or "defecator."

References Cited

[1] Catalog of the historically active volcanoes of Alaska, 1998

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 98-0582, 104 p.

[2] Geology of Little Sitkin Island, Alaska, 1959

Snyder, G. L., 1959, Geology of Little Sitkin Island, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-H, p. 169-210, 1 plate, scale 1:20,000.

Current Activity

No new updates for Little Sitkin volcano since July 14, 2022, 2:40 pm.

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Before an eruption

Ashfall & Preparedness Information

During and After an Eruption

Other Useful Links

Ash Forecasting

Mathematical models developed by the USGS forecast various aspects of how a volcanic ash plume will interact with wind—where, how high, and how fast ash particles will be transported in the atmosphere, as well as where ash will fall out and accumulate on the ground. AVO runs these models when a volcano is restless by assuming a reasonable hypothetical eruption, to provide a pre-eruptive forecast of areas likely to be affected. During an ongoing eruption, AVO will update the forecast with actual observations (eruption start time and duration, plume height) as they become available.

View the current airborne ash cloud models for Little Sitkin

Ashfall thickness forecast

The Ash3d model was developed by the USGS to forecast how a volcanic ash plume will interact with wind and where ash will fall out and accumulate on the ground. AVO runs these models twice daily when a volcano is restless by assuming a reasonable hypothetical eruption altitude and duration. The map shows the model results of ashfall thickness for areas that are likely to be affected, if one were to occur. During an ongoing eruption, AVO will update the forecast with actual observations (eruption start time and duration, plume height) as they become available, and these plots will be automatically updated. The National Weather Service Anchorage Forecast Office will issue the official ashfall warning product and post them at weather.gov/afc

THESE PRODUCTS MAY NOT BE CURRENT.

During an actual eruption, see National Weather Service forecasts of ashfall:https://weather.gov/afc.

Ashfall Forecast

Click on the X on the graphic (upper right) to expand the map to show the map legend.

Ashfall Start Time

This map shows the modeled estimate of the time it would take for ashfall to begin following an eruption. It corresponds to the ashfall thickness forecast map shown above. This map uses the start time of either the twice-daily hypothetical model runs (time shown in the legend) or the actual eruption start time (if one were to occur). In the case of an actual eruption, the National Weather Service Anchorage Forecast Office will issue the official ashfall warning product that includes the ashfall start time and post them at weather.gov/afc

THESE PRODUCTS MAY NOT BE CURRENT.

During an actual eruption, see National Weather Service forecasts of ashfall:https://weather.gov/afc.

Ashfall Start Times Forecast

Click on the X on the graphic (upper right) to expand the map to show the map legend.