Most Recent Weekly Report: 9 January-15 January 2013 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Weekly Reports - Index

2013: January
2012: August | September | October

9 January-15 January 2013 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

17 October-23 October 2012 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

19 September-25 September 2012 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

12 September-18 September 2012 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

5 September-11 September 2012 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

29 August-4 September 2012 Cite this Report

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

The Global Volcanism Program has no Bulletin Reports available for Little Sitkin.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Synonyms

Little Sitchin | Sitchin | Sitignak (?) | Malyi Sitkin

Basic Data Volcano Number Last Known Eruption Elevation Latitude Longitude 311050 1830 CE 1174 m / 3851 ft 51.95°N 178.543°E Volcano Types Stratovolcano Caldera(s) Rock Types Major Andesite / Basaltic Andesite Dacite Tectonic Setting Subduction zone Intermediate crust (15-25 km) Population Within 5 km Within 10 km Within 30 km Within 100 km 0 0 0 0

Geological Summary 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. References The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. 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.

Eruptive History

There is data available for 2 Holocene eruptive periods.

Start Date	Stop Date	Eruption Certainty	VEI	Evidence	Activity Area or Unit
1828	1830	Confirmed		Historical Observations	Summit and west flank
1776	Unknown	Confirmed	1	Historical Observations

Deformation History

There is no Deformation History data available for Little Sitkin.

Emission History

There is no Emissions History data available for Little Sitkin.

Photo Gallery

Snow-covered Little Sitkin volcano rises beyond Williwaw Cove on the NW side of the island. The sharp-topped unnamed peak at the left is part of the Williwaw Cove Formation, consisting of Tertiary to Quaternary lava flows. Two nested calderas lie between this peak and historically active Little Sitkin; the younger of these may be of early Holocene age. The older Pleistocene caldera, whose low rim lies just beyond the thin cloud bank in the center, may have once contained a caldera lake. Photo by Steve Ebbert, 2000 (U.S. Fish and Wildlife Service).

Smithsonian Sample Collections Database

The following 5 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections, and may be availble for research (contact the Rock and Ore Collections Manager). Catalog number links will open a window with more information.

Catalog Number	Sample Description	Lava Source	Collection Date
NMNH 118208-1	Scoriaceous tephra	--	9 Sep 2015
NMNH 118208-2	Scoriaceous tephra	--	9 Sep 2015
NMNH 118208-3	Basaltic Andesite	--	9 Sep 2015
NMNH 118208-4	Scoriaceous tephra	--	9 Sep 2015
NMNH 118208-5	Scoriaceous tephra	--	9 Sep 2015

Affiliated Sites

WOVOdat    Single Volcano View    Temporal Evolution of Unrest    Side by Side Volcanoes	WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
Large Eruptions of Little Sitkin	Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
MIROVA	Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.
MODVOLC Thermal Alerts	Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
EarthChem	EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).