On 9 January, AVO reported that unrest at Little Sitkin had decreased over the past several months, reaching background levels. The Volcano Alert Level was lowered to Normal and the Aviation Color Code was lowered to Green.

All times are local (= UTC - 9 hours [or 8 hours early April-late October])

2013: January |
2012: August | September | October |

9 January 2013              Back to Top

On 9 January, AVO reported that unrest at Little Sitkin had decreased over the past several months, reaching background levels. The Volcano Alert Level was lowered to Normal and the Aviation Color Code was lowered to Green.

Sources: Alaska Volcano Observatory (AVO)

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17 October 2012              Back to Top

AVO reported that during 17-23 October seismic activity at Little Sitkin remained elevated and satellite views were mostly obscured by clouds. AVO noted that there were no other reports of unusual activity. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Sources: Alaska Volcano Observatory (AVO)

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19 September 2012              Back to Top

AVO reported that during 19-24 September seismic activity at Little Sitkin remained elevated and satellite views were mostly obscured by clouds. On 21 September AVO noted that the frequency of earthquakes had declined during the previous week. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Sources: Alaska Volcano Observatory (AVO)

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12 September 2012              Back to Top

AVO reported that during 11-18 September seismic activity at Little Sitkin remained elevated and satellite views were obscured by clouds. Two earthquake swarms were detected on 11 and 13 September. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Sources: Alaska Volcano Observatory (AVO)

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5 September 2012              Back to Top

AVO reported that during 5-11 September seismic activity at Little Sitkin was much lower than the peak of activity during 29-30 August, but continued to remain elevated. Satellite views were obscured by clouds during 5 and 8-11 September. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Sources: Alaska Volcano Observatory (AVO)

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29 August 2012              Back to Top

AVO reported that at approximately 1915 on 29 August a swarm of high-frequency earthquakes was detected at Little Sitkin. The anomalous seismic activity continued through the night, prompting AVO to raise the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. The rate of anomalous seismicity varied during 30-31 August; the two most active periods were during the morning of 30 August and at about 0400 on 31 August. The rate of earthquakes started to decline at around 0600 on 31 August, but remained elevated through 3 September. Little Sitkin is monitored by a four-station seismic network as well as satellite imagery.

Sources: Alaska Volcano Observatory (AVO)

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Below is a summary of eruption dates and Volcanic Explosivity Indices (VEI).

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Coats R R, 1950. Volcanic activity in the Aleutian Arc. {U S Geol Surv Bull}, 974-B: 35-47

Henning R A, Rosenthal C H, Olds B, Reading E (eds), 1976. Alaska's volcanoes, northern link in the ring of fire. {Alaska Geog}, 4: 1-88

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. {IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior}.

Miller T P, McGimsey R G, Richter D H, Riehle J R, Nye C J, Yount M E, Dumoulin J A, 1998. Catalogue of the historically active volcanoes of Alaska. {U S Geol Surv Open-File Rpt}, 98-582: 1-104

Motyka R J, Liss S A, Nye C J, Moorman M A, 1993. Geothermal resources of the Aleutian arc. {Alaska Div Geol Geophys Surv, Prof Rpt}, no 114, 17 p and 4 map sheets

Myers J D, 1994. {The Geology, Geochemistry and Petrology of the recent Magmatic Phase of the Central and Western Aleutian Arc}. {Unpublished manuscript}, unpaginated

Smith R L, Shaw H R, Luedke R G, Russell S L, 1978. Comprehensive tables giving physical data and thermal energy estimates for young igneous systems of the United States. {U S Geol Surv Open-File Rpt}, 78-925: 1-25

Snyder G L, 1959. Geology of Little Sitkin Island, Alaska. {U S Geol Surv Bull}, 1028-H: 169-210

Wood C A, Kienle J (eds), 1990. {Volcanoes of North America}. Cambridge, England: Cambridge Univ Press, 354 p

Diamond-shaped Little Sitkin Island is bounded by steep cliffs on the east, north, and NE sides. Little Sitkin volcano contains two nested calderas. The older, nearly circular Pleistocene caldera is 4.8 km wide, may have once contained a caldera lake, and was partially filled by a younger cone formed mostly of andesitic and dacitic lava flows. The elliptical younger caldera is 2.7 x 4 km wide; it lies within the eastern part of the older caldera and shares its eastern and southern rim. The younger caldera partially destroyed the lava cone within the first caldera and is of possible early Holocene age. Young-looking dacitic lava flows, erupted in 1828 (Kay, in Wood and Kienle 1990), issued from the central cone within the younger caldera and from a vent on the west flank outside the older caldera. Fumarolic areas are found near the western coast, along the NW margin of the older caldera, and from the summit crater down the southern flank for a 1 km distance.