On 19 October, AVO reported that recent clear satellite views of Shishaldin showed no activity; the last thermal anomaly was detected on 16 August. Seismicity was variable, but within background levels. The Aviation Color Code was lowered to Green and the Volcano Alert Level was lowered to Normal.

14 October 2009            Back to Top

On 19 October, AVO reported that recent clear satellite views of Shishaldin showed no activity; the last thermal anomaly was detected on 16 August. Seismicity was variable, but within background levels. The Aviation Color Code was lowered to Green and the Volcano Alert Level was lowered to Normal.

Sources: Alaska Volcano Observatory (AVO)

8 July 2009            Back to Top

On 10 July, AVO reported that a distinct thermal anomaly in Shishaldin's summit crater observed intermittently since January 2009 became more intense during the previous month. AVO raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. AVO also noted that seismicity had not increased, deformation was unchanged, and satellite observations showed no significant sulfur dioxide gas emissions. Some reports of steaming from the summit crater were received.

Sources: Alaska Volcano Observatory (AVO)

11 February 2009            Back to Top

AVO reported that seismic activity from Shishaldin had returned to background levels in December 2008 and remained low. On 3 February, a weak thermal anomaly was detected on satellite imagery. The Aviation Color Code was lowered to Green and the Volcano Alert Level was lowered to Normal on 11 February.

Sources: Alaska Volcano Observatory (AVO)

7 January 2009            Back to Top

AVO reported that thermal anomalies over Shishaldin's summit were detected in satellite imagery during 7-10 January. Clouds prevented observations on 11, 12, and 13 January. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Sources: Alaska Volcano Observatory (AVO)

31 December 2008            Back to Top

AVO reported that significant thermal anomalies over Shishaldin's summit were detected in satellite imagery during 5-6 January. Seismic activity had also increased slightly. AVO raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory.

Sources: Alaska Volcano Observatory (AVO)

6 February 2008            Back to Top

Based on pilot reports, the Anchorage VAAC reported that a small ash plume from Shishaldin rose to an altitude of 3 km (10,000 ft) a.s.l. on 12 February. Ash was not observed on satellite imagery. [Note: AVO received no other reports of an ash plume and did not detect ash on satellite imagery.]

Sources: Anchorage Volcanic Ash Advisory Center (VAAC)

20 October 2004            Back to Top

On 26 October, AVO lowered the Concern Color Code at Shishaldin from Yellow to Green. Volcanic tremor at the volcano had remained at a relatively constant and low level for more than a month. No new satellite observations indicative of significant activity in the summit crater had been received by AVO, and there had been no recent reports of ash emissions or ash on the snow near the summit. The low-level seismic tremor that continued to be recorded at the volcano was considered to be representative of the background rate of activity at Shishaldin.

Sources: Alaska Volcano Observatory (AVO)

15 September 2004            Back to Top

Low-level seismic tremor continued to be recorded at Shishaldin during 10-17 September. This level of activity is similar to that observed over the past several months. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

28 July 2004            Back to Top

Low-level seismic tremor continued at Shishaldin during 22-30 July as it had for several months. On 24 July an AVO field crew observed vigorous steaming at the summit and what may have been ash deposits on the volcano's upper slopes. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

7 July 2004            Back to Top

Low-level seismic activity characterized by weak but continuous tremor continued at Shishaldin during 7-13 July. No volcanic activity was observed at the volcano during clear weather, but AVO reported that satellite data indicated the crater to be warmer than the surrounding ground surface. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

23 June 2004            Back to Top

Seismic unrest continued at Shishaldin during 18-25 June, with weak tremor and occasional discrete low-frequency earthquakes occurring. A pilot reported seeing steam rise to low levels above Shishaldin's cone. Around that time, a possible weak thermal anomaly was visible on satellite imagery. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO) , Anchorage Volcanic Ash Advisory Center (VAAC)

26 May 2004            Back to Top

Seismic unrest continued at Shishaldin during 21-28 May. It was characterized by weak seismic tremor and occasional discrete low-frequency earthquakes. Meteorological clouds obscured views of the volcano. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

19 May 2004            Back to Top

During 14-21 May seismic unrest continued at Shishaldin, characterized by weak seismic tremor and small explosions. On 16 May, a pilot reported an ash plume that rose ~300 m above the volcano's summit. Satellite imagery from 17 May showed a vigorous plume emanating from the summit that may have contained small amounts of ash. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

12 May 2004            Back to Top

During 7-14 May seismic unrest continued at Shishaldin, characterized by sequences of volcanic earthquakes, small explosions, and seismic tremor. A weak thermal anomaly observed at Shishaldin's summit on 11 May was similar to those detected occasionally since January 2004. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

5 May 2004            Back to Top

Seismic unrest continued at Shishaldin during 30 April to 7 May. It was characterized by sequences of volcanic earthquakes and seismic tremor. The number of airwaves recorded by the seismic network diminished in comparison to the previous week, but weaker signals were recorded. Thermal anomalies at the summit were observed on satellite imagery under optimal viewing conditions. Retrospective analysis confirmed that these data, as well as similar signals observed in January 2004, were the first thermal anomalies observed at Shishaldin since August 2000. AVO saw no signs that an eruption was imminent. Shishaldin remained at Concern Color Code Yellow.

Sources: Alaska Volcano Observatory (AVO)

28 April 2004            Back to Top

AVO raised the Concern Color Code at Shishaldin from Green to Yellow on 3 May due to unusual seismic activity at Shishaldin during the previous week. Seismicity changed at the volcano from discrete earthquakes to more continuous ones. Tremor was observed for the first time since the most recent eruption ended in May 1999. Airwaves (acoustical waves traveling in air) accompanying earthquakes were recorded by the seismic network, suggesting that the source of seismicity had become more shallow. AVO reported that there were no indications that an eruption was imminent or even likely. Satellite data showed no significant increase in ground temperature at the volcano, nor had there been reports of increased steaming. However, AVO warned that activity at Shishaldin could increase rapidly and increased the frequency of their seismic-data analysis.

Sources: Alaska Volcano Observatory (AVO)

22 May 2002            Back to Top

During 17-24 March, the number of locatable low-frequency seismic events at Shishaldin greatly decreased in comparison to the previous week, returning to background levels. Shishaldin remained at Concern Color Code Green ("volcano is in quiet, "dormant" state").

Sources: Alaska Volcano Observatory (AVO)

15 May 2002            Back to Top

During 10-17 May, the Alaska Volcano Observatory detected an increase in background seismicity at Shishaldin. There was an increase in the number of locatable shallow low-frequency earthquakes and several 2 to- 3-minute-long tremor-like signals that were inferred to be from a deep source. No thermal anomalies were visible on satellite imagery and there were no eyewitness reports of anomalous volcanic activity. Shishaldin remained at Concern Color Code Green ("volcano is in quiet, "dormant" state").

Sources: Alaska Volcano Observatory (AVO)

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.

Beget J E, Nye C J, Schaefer J R, Stelling P L, 2003. Preliminary volcano-hazard assessment for Shishaldin volcano, Alaska. {Alaska Dept Nat Resour Div Geol Geophys Surv, Rep Invest}, 2002-4: 1-28

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

Fournelle J H, 1988. The geology and petrology of Shishaldin volcano, Unimak Island, Aleutian arc, Alaska. {Unpublished PhD thesis}, John Hopkins Univ, 507 p

Green J, Short N M, 1971. {Volcanic Landforms and Surface Features: a Photographic Atlas and Glossary}. New York: Springer-Verlag, 519 p

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

Nye C J, Keith T E C, Eichelberger J C, Miller T P, McNutt S R, Moran S, Schneider D J, Dehn J, Schaefer J R, 2002. The 1999 eruption of Shishaldin volcano, Alaska: monitoring a distant eruption. {Bull Volc}, 64: 507-519

Petersen T, McNutt S R, 2007. Seismo-acoustic signals associated with degassing explosions recorded at Shishaldin Volcano, Alaska, 2003-2004. {Bull Volc}, 69: 527-536

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

Vergniolle S, Caplan-Auerbach C, 2006. Basaltic thermals and subplinian plumes: constraints from measurements at Shishaldin volcano, Alaska. {Bull Volc}, 68: 611-630

The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, Shishaldin is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 m elevation. Shishaldin contains over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.