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Semisopochnoi

Photo of this volcano
  • United States
  • Alaska
  • Stratovolcano
  • 2019 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 51.93°N
  • 179.58°E

  • 1221 m
    4006 ft

  • 311060
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number
Most Recent Weekly Report: 18 September-24 September 2019 Citation IconCite this Report

AVO lowered the Volcano Alert Level for Semisopochnoi to Advisory and the Aviation Color Code to Yellow on 18 September noting a decrease in seismic activity over the past few weeks and an absence of tremor since 15 September. Low-levels sulfur dioxide emissions persisted, and the crater lake continued to fill with water.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


Most Recent Bulletin Report: September 2019 (BGVN 44:09) Citation IconCite this Report

Small explosions detected between 16 July and 24 August 2019

The remote island of Semisopochnoi in the western Aleutians is dominated by a caldera measuring 8 km in diameter that contains a small lake (Fenner Lake) and a number of post-caldera cones and craters. A small (100 m diameter) crater lake in the N cone of Semisopochnoi's Cerberus three-cone cluster has persisted since January 2019. An eruption at Sugarloaf Peak in 1987 included an ash plume (SEAN 12:04). Activity during September-October 2018 included increased seismicity and small explosions (BGVN 44:02). The primary source of information for this reporting period of July-August 2019 comes from the Alaska Volcano Observatory (AVO), when there were two low-level eruptions.

Seismicity rose above background levels on 5 July 2019. AVO reported that data from local seismic and infrasound sensors likely detected a small explosion on 16 July. A strong tremor on 17 July generated airwaves that were detected on an infrasound array 260 km E on Adak Island. In addition to this, a small plume extended 18 km WSW from the Cerberus vent, but no ash signals were detected in satellite data. Seismicity decreased abruptly on 18 July after a short-lived eruption. Seismicity increased slightly on 23 July and remained elevated through August.

On 24 July 2019 AVO reported that satellite data showed that the crater lake was gone and a new, shallow inner crater measuring 80 m in diameter had formed on the crater floor, though no lava was identified. Satellite imagery indicated that the crater of the Cerberus N cone had been replaced by a smooth, featureless area of either tephra or water at a level several meters below the previous floor. Satellite imagery detected faint steam plumes rising to 5-10 km altitude and minor SO2 emissions on 27 July. Satellite data showed a steam plume rising from Semisopochnoi on 18 August and SO2 emissions on 21-22 August. Ground-coupled airwaves identified in seismic data on 23-24 August was indicative of additional explosive activity.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/).

Weekly Reports - Index


2019: July | August | September
2018: September | October | November
2015: April | May
2014: June


18 September-24 September 2019 Citation IconCite this Report

AVO lowered the Volcano Alert Level for Semisopochnoi to Advisory and the Aviation Color Code to Yellow on 18 September noting a decrease in seismic activity over the past few weeks and an absence of tremor since 15 September. Low-levels sulfur dioxide emissions persisted, and the crater lake continued to fill with water.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


4 September-10 September 2019 Citation IconCite this Report

AVO reported that low-level eruptive activity at Semisopochnoi possibly continued during 4-10 September. Seismic activity was relatively minor and characterized by intermittent low-frequency earthquakes. Satellite images were mostly cloudy, though a low-altitude steam plume drifting 50 km S was visible on 8 September. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


28 August-3 September 2019 Citation IconCite this Report

AVO reported that low-level eruptive activity at Semisopochnoi possibly continued during 28 August-3 September. Seismic activity was relatively minor and characterized by intermittent low-frequency earthquakes. Minor tremor was detected until 30 August. Satellite images were obscured by clouds. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


21 August-27 August 2019 Citation IconCite this Report

AVO reported that during 17-23 August seismicity at Semisopochnoi remained elevated and was characterized by periods of continuous tremor and discrete low-frequency earthquakes; seismic data went offline starting sometime on 17 August, though was available by around 22 August. Ground-coupled airwaves, indicative of explosive activity, were sometimes recorded in seismic data; an infrasound signal was recorded during 23-24 August. Cloudy weather often prevented satellite views of the volcano, though a steam plume was visible on 18 August and sulfur dioxide emissions were detected during 21-22 August. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


14 August-20 August 2019 Citation IconCite this Report

AVO reported that during 14-17 August seismicity at Semisopochnoi remained elevated and was characterized by periods of continuous tremor and discrete low-frequency earthquakes; seismic data became unavailable starting sometime on 17 August. Cloudy weather often prevented satellite views of the volcano, however some recent clear views indicated that the N cone crater had a smooth featureless area, indicating water or tephra at an elevation several meters below the previous floor. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


7 August-13 August 2019 Citation IconCite this Report

AVO reported that during 7-13 August seismicity at Semisopochnoi remained elevated and was characterized by periods of continuous tremor and discrete low-frequency earthquakes. No unusual activity was observed in satellite images, though views were often cloudy. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


31 July-6 August 2019 Citation IconCite this Report

AVO reported that during 31 July-6 August seismicity at Semisopochnoi remained elevated and was characterized by periods of weak, continuous tremor and discrete low-frequency earthquakes. Satellite images were mostly cloudy, though a possible steam plume was visible during 5-6 August. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


24 July-30 July 2019 Citation IconCite this Report

On 24 July AVO reported that satellite data from the previous week indicated that the 100-m-wide crater lake in the N cone of Semisopochnoi’s Cerberus three-cone cluster was gone, and a new shallow inner crater about 80 m in diameter had formed on the crater floor. The lake had persisted since January 2019. Seismicity during 25-30 July was characterized by periods of continuous tremor, low-frequency earthquakes, and small explosion signals. Small steam plumes were visible in periodic, cloud-free satellite images, along with minor sulfur dioxide emissions.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


17 July-23 July 2019 Citation IconCite this Report

AVO reported that data from local seismic and infrasound sensors likely detected a small explosion at Semisopochnoi on 16 July. No ash was visible in cloudy satellite images although none was expected from an explosion of its size. A small plume drifted 18 km from the vent but had no indication of ash. A strong tremor signal was recorded at 2339 on 17 July and an infrasound signal was detected from an array located 260 km E on Adak Island. The event likely produced ash emissions, though none were visible above the cloud deck at 3 km (10,000 ft) a.s.l. Seismic activity continued to increase. On 18 July a short-lived, low-level eruption prompted AVO to raise the Aviation Color Code to Orange (the second highest level on a four-color scale) and the Volcano Alert Level to Watch (the second highest level on a four-level scale). A low-level plume was visible in occasional cloud-free satellite images. Seismic activity decreased abruptly that night and ground-coupled airwaves stopped being detected on adjacent islands, suggesting that the eruption had paused or ended. Seismic activity remained low at least through 21 July.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


3 July-9 July 2019 Citation IconCite this Report

An increase in seismicity above background levels on 4 July at Semisopochnoi prompted AVO to raise the Aviation Color Code to Orange (the second highest level on a four-color scale) and the Volcano Alert Level to Watch (the second highest level on a four-level scale). Elevated seismicity continued through at least 9 July. No eruptive activity was detected in regional infrasound data, and cloudy conditions obscured satellite views of the volcano. [Correction: the Aviation Color Code was raised to Yellow and the Volcano Alert Level was raised to Advisory.]

Source: US Geological Survey Alaska Volcano Observatory (AVO)


21 November-27 November 2018 Citation IconCite this Report

AVO reported that no evidence of activity at Semisopochnoi had been detected since an explosion was recorded in infrasound data on 31 October. The satellite link for transmitting seismic data failed on 1 November, though no activity was observed in satellite or infrasound data since then. As a result, the Aviation Color Code was lowered to Yellow and Volcano Alert Level was lowered to Advisory (both are the second lowest levels on four-level scales) on 21 November.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


7 November-13 November 2018 Citation IconCite this Report

AVO reported that three possible small explosions at Semisopochnoi were detected in infrasound data between 1951 and 2004 on 9 November. No associated ash clouds were observed in partly cloudy satellite images, and no other activity was noted during 7-11 November also in partly cloudy images. Images were cloudy during 12-13 November. The Aviation Color Code remained at Orange and Volcano Alert Level remained at Watch (both are the second highest levels on four-level scales).

Source: US Geological Survey Alaska Volcano Observatory (AVO)


31 October-6 November 2018 Citation IconCite this Report

AVO reported that two small explosions at Semisopochnoi were detected in seismic and infrasound data on 31 October. Intermittent seismic tremor was recorded on 1 November but later that day the satellite link that transmits seismic data failed. Weather clouds obscured views of the volcano during 31 October-4 November. Nothing was observed in satellite data during 5-6 November. The Aviation Color Code remained at Orange (the second highest level on a four-color scale) and Volcano Alert Level remained at Watch (the second highest level on a four-level scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)


24 October-30 October 2018 Citation IconCite this Report

AVO reported that an eruptive event at Semisopochnoi began at 2047 on 25 October based on seismic data; strong volcanic tremor lasted about 20 minutes and was followed by 40 minutes of weak tremor pulses. A weak infrasound signal was detected by instruments on Adak Island (260 km SE). The Aviation Color Code was raised to Orange (the second highest level on a four-color scale) and Volcano Alert Level was raised to Watch (the second highest level on a four-level scale). A dense meteorological cloud deck prevented observations below 3 km (10,000 ft) a.s.l.; a diffuse cloud was observed in satellite data rising briefly above the cloud deck, though it was unclear if it was related to eruptive activity. Tremor ended after the event, and seismicity returned to low levels.

Small explosions were detected by the seismic network at 2110 and 2246 on 26 October and 0057 and 0603 on 27 October. No ash clouds were identified in satellite data, but the volcano was obscured by high meteorological clouds. Additional small explosions were detected in seismic and infrasound data during 28-29 October; no ash clouds were observed in partly-cloudy-to-cloudy satellite images.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


10 October-16 October 2018 Citation IconCite this Report

On 11 October AVO reported that satellite data of Semisopochnoi indicated partial erosion of a tephra cone in the crater of Cerberus’s N cone. A crater lake about 90 m in diameter filled the vent. The data also suggested that the vent had not erupted since 1 October. Seismicity remained elevated and above background levels. The next day AVO lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory, noting the recent satellite data results and lack of tremor recorded during the previous week.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


3 October-9 October 2018 Citation IconCite this Report

AVO reported that during 3-9 October seismicity at Semisopochnoi remained elevated, with intermittent bursts of tremor. No volcanic activity was detected in infrasound or satellite data. The Aviation Color Code (ACC) remained at Yellow and Volcano Alert Level (VAL) remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


26 September-2 October 2018 Citation IconCite this Report

AVO reported that during 19-25 September seismicity at Semisopochnoi remained elevated, alternating between periods of continuous and intermittent bursts of tremor. Tremor bursts at 1319 on 21 September and at 1034 on 22 September produced airwaves detected on a regional infrasound array on Adak Island; no ash emissions were identified above the low cloud deck in satellite data, and the infrasound detections likely reflected an atmospheric change instead of volcanic activity. The Aviation Color Code (ACC) remained at Yellow and Volcano Alert Level (VAL) remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


19 September-25 September 2018 Citation IconCite this Report

AVO reported that during 19-25 September seismicity at Semisopochnoi remained elevated, alternating between periods of continuous and intermittent bursts of tremor. Tremor bursts at 1319 on 21 September and at 1034 on 22 September produced airwaves detected on a regional infrasound array on Adak Island; no ash emissions were identified above the low cloud deck in satellite data, and the infrasound detections likely reflected an atmospheric change instead of volcanic activity. The Aviation Color Code (ACC) remained at Yellow and Volcano Alert Level (VAL) remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


12 September-18 September 2018 Citation IconCite this Report

On 16 September AVO raised the Aviation Color Code (ACC) for Semisopochnoi to Yellow and Volcano Alert Level (VAL) to Advisory after increased seismicity was detected at 0831. Retrospective analysis of satellite data acquired on 10 September revealed small ash deposits on the N flank of Mount Cerberus, possibly associated with two bursts of tremor recorded on 8 September. This new information coupled with intensifying seismicity and a strong tremor signal recorded at 1249 on 17 September prompted AVO to raise the ACC to Orange and the VAL to Watch. Seismicity remained elevated on 18 September with nearly constant tremor being recorded by local sensors.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


27 May-2 June 2015 Citation IconCite this Report

A decline in seismicity at Semisopochnoi over the previous few months, and no activity observed in satellite images, prompted AVO to lower the Aviation Color Code and the Volcano Alert Level to Unassigned on 28 May. Increased seismicity had been detected in January.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


1 April-7 April 2015 Citation IconCite this Report

On 25 March AVO reported that seismicity at Semisopochnoi that had begun in January continued and had increased over the previous few days. Brief periods of tremor were also detected. AVO raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. The elevated seismicity, characterized by discrete fairly small earthquakes beneath the center of the island, continued to be detected through 7 April.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


18 June-24 June 2014 Citation IconCite this Report

AVO reported that the earthquake swarm that had started at Semisopochnoi on 9 June continued until 23 June. No eruptive activity was indicated. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


11 June-17 June 2014 Citation IconCite this Report

AVO reported that an earthquake swarm at Semisopochnoi started at 1000 on 9 June and escalated at 1200 on 12 June. The continuation of the anomalous activity prompted AVO to raise the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory on 13 June. The earthquake swarm was continuing as of 17 June. Five of the six seismic stations on the volcano were operational.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


Bulletin Reports - Index

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

04/1987 (SEAN 12:04) Plume; possible ash deposits

02/2019 (BGVN 44:02) Minor ash explosions during September and October 2018

09/2019 (BGVN 44:09) Small explosions detected between 16 July and 24 August 2019




Information is preliminary and subject to change. All times are local (unless otherwise noted)


April 1987 (SEAN 12:04) Citation IconCite this Report

Plume; possible ash deposits

A plume originating at about 52°N, 180° and extending 90 km ENE was noted by Steven Shivers from a NOAA 9 satellite image returned 13 April at 1731. On an image at 2135 the same day, the plume extended only 15 km ENE. On 24 April, pilot Harold Wilson (Peninsula Airways), flying 50 km SE of Semisopochnoi, noted a very dark-colored peak (perhaps Sugarloaf) among other snow-covered mountains on the island. Plumes from Semisopochnoi were reported several times in the 18th and 19th centuries.

Information Contacts: J. Reeder, ADGGS; T. Miller, USGS, Anchorage; W. Gould, NOAA/NESDIS.


February 2019 (BGVN 44:02) Citation IconCite this Report

Minor ash explosions during September and October 2018

The remote Semisopochnoi comprises the uninhabited volcanic island of the same name, ~20 km in diameter, in the Rat Islands group of the western Aleutians (figure 1). Plumes had been reported several times in the 18th and 19th centuries, and most recently observed in April 1987 from Sugarloaf Peak (SEAN 12:04). The volcano is dominated by an 8-km diameter caldera that contains a small lake (Fenner Lake) and a number of post-caldera cones and craters. Monitoring is done by the Alaska Volcano Observatory (AVO) using an on-island seismic network along with satellite observations and lightning sensors. An infrasound array on Adak Island, about 200 km E, may detect explosive emissions with a 13 minute delay if atmospheric conditions permit.

On 16 September 2018 increased seismicity was detected at 0831, prompting AVO to raise the Aviation Color Code (ACC) to Yellow and Volcano Alert Level (VAL) to Advisory. Retrospective analysis of satellite data acquired on 10 September revealed small ash deposits on the N flank of Mount Cerberus, possibly associated with two bursts of tremor recorded on 8 September (figure 5). This new information, coupled with intensifying seismicity and a strong tremor signal recorded at 1249 on 17 September, resulted in AVO raising the ACC to Orange and the VAL to Watch. Seismicity remained elevated on 18 September with nearly constant tremor recorded by local sensors. At the same time, no ash emissions were observed in cloudy satellite images and no eruptive activity was recorded on regional pressure sensors at Adak.

Figure (see Caption) Figure 1. Minor ash deposits can be seen on the south and west flanks of the N cone of Mount Cerberus, Semisopochnoi Island, in this ESA Sentinel-2 image from 1200 on 10 September 2018. Also note probable minor steam emissions obscuring the crater of the N cone. Image courtesy of AVO.

During 19-25 September 2018 seismicity remained elevated, alternating between periods of continuous and intermittent bursts of tremor. Tremor bursts at 1319 on 21 September and at 1034 on 22 September produced airwaves detected on a regional infrasound array on Adak Island; no ash emissions were identified above the low cloud deck in satellite data, and the infrasound detections likely reflected an atmospheric change instead of volcanic activity.

Seismicity remained elevated during 3-9 October 2018, with intermittent bursts of tremor. No volcanic activity was detected in infrasound or satellite data. On 11 October satellite data indicated partial erosion of a tephra cone in the crater of Cerberus's N cone. A crater lake about 90 m in diameter filled the vent. The data also suggested that the vent had not erupted since 1 October. Seismicity remained elevated and above background levels. The next day AVO lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory, noting the recent satellite data results and lack of tremor recorded during the previous week. AVO reported that unrest continued during 11-24 October.

An eruptive event began at 2047 on 25 October 2018, identified based on seismic data; strong volcanic tremor lasted about 20 minutes and was followed by 40 minutes of weak tremor pulses. A weak infrasound signal was detected by instruments on Adak Island. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale) and Volcano Alert Level was raised to Watch (the second highest level on a four-level scale). A dense meteorological cloud deck prevented observations below 3 km, but a diffuse cloud was observed in satellite data rising briefly above the cloud deck, though it was unclear if it was related to eruptive activity. Tremor ended after the event, and seismicity returned to low levels.

Small explosions were detected by the seismic network at 2110 and 2246 on 26 October 2018, and 0057 and 0603 on 27 October. No ash clouds were identified in satellite data, but the volcano was obscured by high meteorological clouds. Additional small explosions were detected in seismic and infrasound data during 28-29 October; no ash clouds were observed in partly-cloudy-to-cloudy satellite images.

AVO reported on 31 October 2018 that unrest continued. Two small explosions were detected, one just before 0400 and the other around 1000. Satellite views were obscured by clouds at the time, and no ash clouds were observed. Unrest continued through 1 November, at which time the satellite link and the seismic line failed. On 21 November the ACC was lowered to Yellow and the VAL was lowered to Advisory.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/).


September 2019 (BGVN 44:09) Citation IconCite this Report

Small explosions detected between 16 July and 24 August 2019

The remote island of Semisopochnoi in the western Aleutians is dominated by a caldera measuring 8 km in diameter that contains a small lake (Fenner Lake) and a number of post-caldera cones and craters. A small (100 m diameter) crater lake in the N cone of Semisopochnoi's Cerberus three-cone cluster has persisted since January 2019. An eruption at Sugarloaf Peak in 1987 included an ash plume (SEAN 12:04). Activity during September-October 2018 included increased seismicity and small explosions (BGVN 44:02). The primary source of information for this reporting period of July-August 2019 comes from the Alaska Volcano Observatory (AVO), when there were two low-level eruptions.

Seismicity rose above background levels on 5 July 2019. AVO reported that data from local seismic and infrasound sensors likely detected a small explosion on 16 July. A strong tremor on 17 July generated airwaves that were detected on an infrasound array 260 km E on Adak Island. In addition to this, a small plume extended 18 km WSW from the Cerberus vent, but no ash signals were detected in satellite data. Seismicity decreased abruptly on 18 July after a short-lived eruption. Seismicity increased slightly on 23 July and remained elevated through August.

On 24 July 2019 AVO reported that satellite data showed that the crater lake was gone and a new, shallow inner crater measuring 80 m in diameter had formed on the crater floor, though no lava was identified. Satellite imagery indicated that the crater of the Cerberus N cone had been replaced by a smooth, featureless area of either tephra or water at a level several meters below the previous floor. Satellite imagery detected faint steam plumes rising to 5-10 km altitude and minor SO2 emissions on 27 July. Satellite data showed a steam plume rising from Semisopochnoi on 18 August and SO2 emissions on 21-22 August. Ground-coupled airwaves identified in seismic data on 23-24 August was indicative of additional explosive activity.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/).

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.

Eruptive History

There is data available for 8 Holocene eruptive periods.

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2019 Jul 16 2019 Aug 24 Confirmed   Historical Observations
2018 Sep 8 2018 Oct 31 Confirmed 1 Historical Observations
1987 Apr 13 Unknown Confirmed 2 Historical Observations Sugarloaf ?
1873 Unknown Confirmed   Historical Observations Cerberus
[ 1830 ] [ Unknown ] Uncertain     Cerberus
[ 1792 ] [ Unknown ] Uncertain     Cerberus
[ 1790 ] [ Unknown ] Uncertain     Cerberus
[ 1772 ] [ Unknown ] Uncertain     Cerberus
Deformation History

There is data available for 1 deformation periods. Expand each entry for additional details.


Deformation during 2004 - 2010 [Subsidence; Observed by InSAR]

Start Date: 2004 Stop Date: 2010 Direction: Subsidence Method: InSAR
Magnitude: 6.000 cm Spatial Extent: 4.00 km Latitude: 52.000 Longitude: 180.000

Remarks: Deformation centered on Mt. Cerberus is probably caused by surface processes such as contraction of volcanic deposits, gravitational sliding, and mechanical compaction.

Figure (see Caption)

a Average line-of-sight surface displacement rate map for Mount Cerberus from SBAS processing of 11 ascending-track Envisat images, some of which are shown in Fig. 6.13. Arrows in (a) and (b) indicate flight and look directions of Envisat SAR when images were acquired. b Deformation interferogram for the time period August 1, 2008?August 21, 2009 from Envisat descending track 459. c Time-series of LOS surface displacement at the peak of deformation in (a)

From: Lu and Dzurisin 2014.


Reference List: Lu and Dzurisin 2014.

Full References:

Lubis, A. M., 2014. Uplift of Kelud Volcano Prior to the November 2007 Eruption as Observed by L-Band Insar. Journal of Engineering and Technological Sciences, 46(3), 245-257.

Emission History

There is no Emissions History data available for Semisopochnoi.

Photo Gallery

An aerial view of the SE coast of Semisopochnoi Island shows conical Sugarloaf peak (left-center) with its double parasitic cone (foreground) that was the source of one of the more recent flows. Sugarloaf was erupted outside the southern margin of an 8-km-wide caldera cutting Semisopochnoi. Cloud-draped Mount Cerebus was constructed within the caldera and forms the left horizon. Pre-caldera Ragged Top (right) shows a remnant constructional surface on its seaward face.

Photo by U.S. Navy (published in U.S. Geological Survey Bulletin 1028-O).
See title for photo information.
The western slopes of symmetrical Sugarloaf Peak (left) rise above tundra-covered Semisopochnoi Island. Semisopochnoi, the largest subaerial volcano of the western Aleutians, is 20 km wide at sea level and contains an 8-km-wide caldera. Three-peaked Mount Cerberus volcano was constructed within the caldera during the Holocene, along with symmetrical Sugarloaf Peak volcano outside of the caldera to the SSE. Most documented historical eruptions have originated from Cerberus.

Photo by Steve Ebbert, 1997 (U.S. Fish and Wildlife Service).
See title for photo information.
GVP Map Holdings

The Global Volcanism Program has no maps available for Semisopochnoi.

Smithsonian Sample Collections Database

The following 16 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 118209-1 Basalt -- 12 Sep 2015
NMNH 118209-10 Scoria -- 12 Sep 2015
NMNH 118209-11 Lapilli tephra -- 12 Sep 2015
NMNH 118209-12 Scoria -- 12 Sep 2015
NMNH 118209-13 Lapilli tephra -- 12 Sep 2015
NMNH 118209-14 Scoriaceous tephra -- 12 Sep 2015
NMNH 118209-15 Scoriaceous tephra -- 12 Sep 2015
NMNH 118209-16 Scoria -- 12 Sep 2015
NMNH 118209-2 Basalt -- --
NMNH 118209-3 Lapilli tephra -- 12 Sep 2015
NMNH 118209-4 Basalt -- --
NMNH 118209-5 Basalt -- 12 Sep 2015
NMNH 118209-6 Fine ash -- 12 Sep 2015
NMNH 118209-7 Fine ash -- 12 Sep 2015
NMNH 118209-8 Pyroclastic flow -- 12 Sep 2015
NMNH 118209-9 Pyroclastic flow -- 12 Sep 2015
External Sites