Shishaldin

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  • United States
  • Alaska
  • Stratovolcano
  • 2014 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 54.756°N
  • 163.97°W

  • 2857 m
    9371 ft

  • 311360
  • Latitude
  • Longitude

  • Summit
    Elevation

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    Number

Most Recent Weekly Report: 19 November-25 November 2014


AVO reported that intermittent volcanic tremor at Shishaldin continued to be detected during 19-23 November. Elevated crater temperatures were detected in satellite images during periods of clear weather; thermal anomalies were reported during 21-22 November. Seismic activity increased sharply on 24 November, suggesting that the eruption had intensified. Strong thermal anomalies near the summit were detected in satellite images. On 25 November seismicity remained elevated and strongly elevated surface temperatures continued to be detected in satellite images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


Most Recent Bulletin Report: August 2008 (BGVN 33:08)


Pilot report of ash plume in February 2008

Previously reported activity at Shishaldin included the onset of tremor and some unusual earthquakes. For at least one day in July 2004 small ash plumes rose above the summit (BGVN 29:06).

In 2008, only one instance of an ash plume was reported. According to the Anchorage VAAC a pilot reported a small ash plume at an altitude of 3 km on 12 February. The ash plume was not confirmed by satellite imagery or ground observations. AVO did not report any unusual activity during this time. Shishaldin typically emits a relatively steady steam plume, as seen on 2 September 2008 (figure 5).

Figure 5. Shishaldin and a steam plume at sunset taken from a helicopter on 2 September 2008. Image courtesy of Cyrus Read and Alaska Volcano Observatory / U.S. Geological Survey.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA; Anchorage Volcanic Ash Advisory Center (VAAC), Alaska Aviation Weather Unit, NWS NOAA US Dept of Commerce, 6930 Sand Lake Road, Anchorage, AK 99502-1845, USA (URL: http://www.ssd.noaa.gov/).

Index of Weekly Reports


2014: January | February | March | April | May | June | July | August | September | October | November
2009: January | February | July | October
2008: February | December
2004: April | May | June | July | September | October
2002: May

Weekly Reports


19 November-25 November 2014

AVO reported that intermittent volcanic tremor at Shishaldin continued to be detected during 19-23 November. Elevated crater temperatures were detected in satellite images during periods of clear weather; thermal anomalies were reported during 21-22 November. Seismic activity increased sharply on 24 November, suggesting that the eruption had intensified. Strong thermal anomalies near the summit were detected in satellite images. On 25 November seismicity remained elevated and strongly elevated surface temperatures continued to be detected in satellite images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


12 November-18 November 2014

AVO reported that seismicity at Shishaldin remained elevated during 12-18 November. Elevated crater temperatures were detected in satellite images during periods of clear weather. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


5 November-11 November 2014

AVO reported that seismicity at Shishaldin remained elevated during 5-11 November. Satellite and webcam views showed nothing unusual; temperatures at the summit were elevated on 5 November. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


29 October-4 November 2014

AVO reported that mostly cloudy satellite and webcam views showed nothing unusual at Shishaldin during 29 October-4 November, although the low-level eruptive activity continued. Periods of tremor were detected and overall seismicity remained elevated. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


22 October-28 October 2014

AVO reported that partly cloudy satellite images and mostly cloudy webcam views showed nothing unusual at Shishaldin during 21-24 October. Seismicity increased on 25 October, and was followed by a tremor event and elevated surface temperatures detected at the summit in satellite images. Tephra deposits at the summit were noted in clear webcam images on 26 October, indicating that the event was energetic enough to eject material onto the flank from a depth of several hundred meters within the summit crater. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


15 October-21 October 2014

AVO reported that, although cloud cover often obscured views of Shishaldin during 15-21 October, seismicity indicated that a low-level eruption was likely continuing. Elevated surface temperatures at the summit were periodically detected in cloud-free satellite images. Tremor and ground-coupled airwaves from small explosions were occasionally detected in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


8 October-14 October 2014

AVO reported that, although cloud cover often obscured views of Shishaldin during 8-14 October, seismicity indicated a low-level eruption was likely continuing. Strongly elevated surface temperatures at the summit were periodically detected in cloud-free satellite images during 10-11 and 13-14 October. Tremor and ground-coupled airwaves from small explosions were occasionally detected in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


1 October-7 October 2014

AVO reported that seismicity at Shishaldin indicated that a low-level eruption likely continued during 1-7 October. Strongly elevated surface temperatures at the summit were periodically detected in satellite images; cloud cover sometimes obscured satellite and webcam observations. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


24 September-30 September 2014

AVO reported that, although cloud cover sometimes obscured views of Shishaldin during 24-30 September, seismicity indicated that a low-level eruption was possibly continuing. Elevated surface temperatures at the summit were periodically detected in satellite images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


17 September-23 September 2014

AVO reported that, although cloud cover sometimes obscured views of Shishaldin during 17-22 September, seismicity indicated that a low-level eruption was possibly continuing. Elevated surface temperatures at the summit were periodically detected in satellite images. Minor steam emissions were recorded by the web cam on 17 September. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


10 September-16 September 2014

AVO reported that low-level seismicity and eruptive activity continued from Shishaldin during 10-16 September. Observations were frequently restricted due to cloudy conditions, although elevated temperatures were observed on 15 September in one satellite image.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


3 September-9 September 2014

AVO reported that low-level seismicity and eruptive activity continued from Shishaldin during 3-7 September. When weather conditions were favorable, satellite images detected elevated surface temperatures. Observations were restricted on 8-9 September due to cloudy conditions.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


27 August-2 September 2014

AVO reported that during 27 August-2 September low-level eruptive activity continued at Shishaldin volcano. On 28 August a thermal feature was observed and on 31 August a small steam plume was seen in satellite images. During clear weather on 1 September no activity was observed. On 2 September elevated surface temperatures at the summit crater were noted from satellite data. Clouds prevented observations the other days of the week. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


20 August-26 August 2014

AVO reported that during 20-26 August low-level eruptive activity continued at Shishaldin volcano. A steam and gas plume was visible in web camera and satellite images occasionally during the week. On 20 August satellite images showed a steam plume extending 60 km N of the volcano. On 23 August a pilot reported a steam-and-ash plume rose about 300 m (1,000 ft) above the summit and drifted NE. On 20-22 and 26 August elevated surface temperatures at the summit were detected in clear satellite views. Infrasound sensors located in Dillingham and on Akutan Island detected sound waves from the direction of Shishaldin that were consistent with low-level eruptive activity. No significant activity noted in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


13 August-19 August 2014

AVO reported that during 13-19 August eruptive activity continued at Shishaldin volcano. Infrasound sensors located at Dillingham and on Akutan Island detected sound waves from the direction of Shishaldin that are consistent with low-level activity at the volcano. On 13 August a pilot reported a low-level plume from Shishaldin. On the evening of 16 August web camera views showed a steam and gas plume. On 17-19 August elevated surface temperatures were detected in partly cloudy satellite views. Other days satellite and web camera views were obscured by weather. No significant activity was noted in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


6 August-12 August 2014

AVO reported that during 6-12 August low-level eruptive activity continued at Shishaldin volcano. Web camera and satellite images showed the volcano was mostly cloudy over the past week, but intermittent web camera views showed a steam plume above the summit. On 9-10 August sound waves were detected from the direction of Shishaldin on infrasound sensors in Dillingham, consistent with the low-level activity. On 10 August an area of hot, glowing material was observed in the crater during an overflight of the Shishaldin summit. On 11 August elevated surface temperatures were observed in the summit crater. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


30 July-5 August 2014

AVO reported that during 30 July-5 August low-level eruptive activity continued at Shishaldin volcano. Elevated surface temperatures at the summit were detected from satellite data most days except for cloudy conditions 4-5 August. Steaming from the summit crater was visible in web cam images 30 July-1 August and 5 August. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


23 July-29 July 2014

AVO reported that during 23-29 July low-level eruptive activity continued at Shishaldin volcano. Elevated surface temperatures at the summit were detected daily from satellite data. On 26 July satellite and web camera images showed trace dustings of ash over fresh snow in the immediate vicinity of the crater. Web camera images showed short dark streaks of possible debris flow deposits extending from the summit crater on the southeast flank, possibly the result of the melting of snow and ice near the summit due to the increased temperatures in the vicinity of the crater. Web camera and satellite images were mostly obscured due to clouds other days. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


16 July-22 July 2014

AVO reported that during 16-22 July low-level eruptive activity continued at Shishaldin volcano. Elevated surface temperatures at the summit were detected from satellite data daily, slightly increasing 18 July. Steaming from the summit crater was visible in satellite imagery on 16 July. Web-camera images were mostly obscured due to clouds. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


9 July-15 July 2014

AVO reported that during 2-15 July low-level seismicity continued at Shishaldin volcano. Elevated surface temperatures at the summit were detected. A steam and gas plume was intermittently visible rising from the summit and drifting downwind, although satellite and web-camera images were mostly obscured due to clouds. On 9 July small explosions, probably within the summit cone, were detected on seismic and infrasound networks. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


25 June-1 July 2014

AVO reported that during 25 June – 1 July, low-level seismicity continued at Shishaldin volcano. Elevated surface temperatures at the summit were detected. A steam and gas plume was intermittently visible rising from the summit and drifting downwind, although satellite and web-camera images have been mostly cloudy. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


18 June-24 June 2014

AVO reported that Shishaldin’s low-level eruptive activity continued during 18-23 June and elevated surface temperatures were detected in satellite data (20-23 June). The volcano was frequently obscured by clouds and fog, but minor low-level steam plumes were observed in web camera images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


11 June-17 June 2014

AVO reported that, although cloudy conditions frequently obscured webcam and satellite views of Shishaldin during 11-16 June, seismicity indicated that the low-level eruption continued. Strongly elevated surface temperatures at the summit were detected in satellite data on the morning of 16 June. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


4 June-10 June 2014

AVO reported that, although cloud cover frequently obscured views of Shishaldin during 4-9 June, seismicity indicated that the low-level eruption continued. Elevated surface temperatures at the summit were detected in mostly cloudy satellite images during 7-9 June. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


28 May-3 June 2014

AVO reported that, although cloud cover frequently obscured views of Shishaldin during 28 May-3 June, elevated surface temperatures at the summit were detected in satellite images, and minor steam emissions were observed in webcam images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


21 May-27 May 2014

AVO reported that on most days during 21-27 May elevated surface temperatures at Shishaldin's summit were detected in satellite images, and minor steam emissions were observed in webcam images on 21 May. Cloud cover often prevented observations. Seismometers near the volcano detected brief explosion signals during 21-26 May. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


14 May-20 May 2014

AVO reported that during 14-20 May elevated surface temperatures at Shishaldin's summit were detected in satellite images, and minor steam emissions were observed in webcam images. A report from 16 May noted that dark ash-covered snow near the summit was visible on an unspecified day during the past week. Seismometers near the volcano detected brief explosion signals during 17-20 May. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


7 May-13 May 2014

AVO reported that although cloud cover occasionally prevented web-cam and satellite observations of Shishaldin's summit area during 7-13 May, periods of elevated surface temperatures and minor steaming were observed. A report from 9 May noted that dark ash-covered snow near the summit was visible on an unspecified day during the past week. A continuous “tremor-like” signal detected during 0430-0630 on 13 May coincided with a distinct increase in surface temperatures, possibly indicating a Strombolian eruption. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


30 April-6 May 2014

AVO reported that although cloud cover occasionally prevented web-cam and satellite observations of Shishaldin's summit area during 30 April-6 May, periods of elevated surface temperatures and minor steaming were observed. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


23 April-29 April 2014

AVO reported that although cloud cover occasionally prevented web-cam and satellite observations of Shishaldin's summit area during 23-29 April, periods of elevated surface temperatures and minor steaming were observed. No significant changes were detected in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


16 April-22 April 2014

AVO reported that although cloud cover often prevented web-cam and satellite observations of Shishaldin's summit area during 16-22 April, weakly elevated surface temperatures and minor steaming were occasionally observed. No significant changes were detected in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


9 April-15 April 2014

AVO reported that elevated surface temperatures over Shishaldin's summit area were detected in satellite images on most days during 9-15 April; cloud cover occasionally prevented observations. Ground-coupled air waves from small explosions detected by the seismic network decreased during 9-10 April. Minor ash deposits were observed several hundred meters down flanks. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


2 April-8 April 2014

AVO reported that elevated surface temperatures over Shishaldin's summit area were detected in satellite images during 2-8 April. No activity was detected in the seismic data. The webcam showed a steam plume rising from the crater on 6 April. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


26 March-1 April 2014

AVO reported that ground-coupled air waves from small explosions at Shishaldin's summit area were detected in seismic data during 25-27 March, although the energy and rate of occurrence both declined over that time. Elevated surface temperatures were identified in satellite images on 27 March. Based on the elevated surface temperatures and explosions persistent since 18 March AVO raised the Aviation Color Code to Orange and the Volcano Alert Level to Watch on 28 March. Analysis of the data showed that the temperatures were consistent with an eruption of lava within the summit crater. Web-camera images, satellite data, and pilot observations during the previous week indicated only minor steam emissions from the summit crater; there had been no evidence of ash emissions. Explosions were detected during 29-30 March; elevated surface temperatures were identified during 30-31 March.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


19 March-25 March 2014

AVO reported that ground-coupled air waves from small explosions at Shishaldin's summit area were detected in seismic data during 19-25 March. Elevated surface temperatures were identified on most days during this period. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


12 February-18 February 2014

AVO reported that no activity from Shishaldin was observed in party-to-mostly-cloudy satellite images during 12-18 February. The nearest working seismic station detected low seismicity. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


5 February-11 February 2014

AVO reported that elevated surface temperatures in Shishaldin's summit crater were detected in satellite images during 5-6 February. No unusual seismicity was detected by the nearest working station off the flanks of the volcano. A possible ash-poor gas cloud was detected in satellite images beginning at 0645 on 7 February that may have been from a small explosion, too small to be detected by the seismometer but coinciding with a local tiltmeter signal. Satellite image analysis suggested that the short-lived cloud may have risen to an altitude of 7.6 km (25,000 ft) a.s.l. Elevated surface temperatures were not detected after the event, so very little if any hot material was ejected. During 9-11 February elevated surface temperatures were detected in satellite images and a tiltmeter 5.4 km SW of the volcano recorded a small signal. Clear or partly clear web cam images showed no activity. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


29 January-4 February 2014

On 30 January, AVO raised the Aviation Color Code for Shishaldin to Yellow and the Volcano Alert Level to Advisory based on increased surface temperatures detected at the summit crater by satellite images over the previous few days, as well as increased steam emissions observed on 29 January in satellite and web-camera images. No steam emissions were observed during 30-31 January. Elevated surface temperatures were again detected on 1 February.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


14 October-20 October 2009

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


8 July-14 July 2009

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


11 February-17 February 2009

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


7 January-13 January 2009

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


31 December-6 January 2009

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


6 February-12 February 2008

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.]

Source: Anchorage Volcanic Ash Advisory Center (VAAC)


20 October-26 October 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


15 September-21 September 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


28 July-3 August 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


7 July-13 July 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


23 June-29 June 2004

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: US Geological Survey Alaska Volcano Observatory (AVO); Anchorage Volcanic Ash Advisory Center (VAAC)


26 May-1 June 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


19 May-25 May 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


12 May-18 May 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


5 May-11 May 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


28 April-4 May 2004

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


22 May-28 May 2002

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").

Source: US Geological Survey Alaska Volcano Observatory (AVO)


15 May-21 May 2002

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").

Source: US Geological Survey Alaska Volcano Observatory (AVO)


Index of Bulletin Reports


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.

10/1975 (NSEB 01:01) Ash eruptions; continuous activity in September and into October

12/1975 (NSEB 01:03) White steam seen during clear weather

01/1976 (NSEB 01:04) White steam again seen during clear weather

03/1976 (NSEB 01:06) Weak intermittent steaming

04/1976 (NSEB 01:07) Ashfall on the flanks in late April

05/1976 (NSEB 01:08) Ash observed on cone

06/1976 (NSEB 01:09) Steaming observed; flanks about 70% ash-covered

07/1976 (NSEB 01:10) Steam emissions with occasional ash

08/1976 (NSEB 01:11) Occasional steam seen during clear weather

10/1976 (NSEB 01:13) Incandescent gas jet; steam-and-ash emission

11/1976 (NSEB 01:14) Steaming; "smoke" bursts on 24 November

03/1977 (NSEB 02:03) Light steaming seen on one day in February

02/1978 (SEAN 03:02) Large steam plume, accompanying nearby Westdahl eruption

02/1979 (SEAN 04:02) Ash emission increases

09/1981 (SEAN 06:09) Plumes accompany eruption at nearby Pavlof

04/1986 (SEAN 11:04) Increased steam and ash emission

05/1986 (SEAN 11:05) Steam plumes with some ash

08/1986 (SEAN 11:08) Large steam plumes with some ash

09/1986 (SEAN 11:09) Steam and ash emission

12/1986 (SEAN 11:12) Vigorous steam ejection

02/1987 (SEAN 12:02) Small ash eruption followed by steaming

10/1993 (BGVN 18:10) Steam plume observed rising to 1,800 m above the summit

05/1995 (BGVN 20:05) Large steam plume

12/1995 (BGVN 20:11) Eruption sends ash plume above 10 km altitude

01/1996 (BGVN 21:01) Steam plumes; thermal anomaly on satellite images

09/1997 (BGVN 22:09) Small steam-and-ash plume on 2 June

02/1999 (BGVN 24:02) Steam plumes and thermal activity seen at summit

03/1999 (BGVN 24:03) Increased shallow seismicity precede April Strombolian eruptions

04/1999 (BGVN 24:04) Steam-and-ash plume on 19 April rose to 15-20 km and was carried to great distances

08/1999 (BGVN 24:08) Eruption ends after long ash plumes are emitted in late May

02/2000 (BGVN 25:02) Small phreatic explosions during September 1999-January 2000

08/2000 (BGVN 25:08) Thermal anomaly and small explosions on 11 August

05/2002 (BGVN 27:05) Seismicity increases briefly during mid-May 2002

06/2004 (BGVN 29:06) Seismic unrest and modest ash plumes in 2004

08/2008 (BGVN 33:08) Pilot report of ash plume in February 2008




Bulletin Reports

All information contained in these reports is preliminary and subject to change.


10/1975 (NSEB 01:01) Ash eruptions; continuous activity in September and into October

Shishaldin, during the few times it could be observed from Cold Bay, was seen to be continually active in September and into October. At 2215 on 16 September, NOAA's RV Millard Freeman, at 55.55°N, 163.82°W experienced rainfall that contained ash. This continued for 15 minutes while the ship was headed on course 250° true. The ash eruptions had apparently ceased by the end of October.

Information Contacts: P. Sventek, USAF, Cold Bay; T. Miller, USGS, Anchorage.
Download or Cite this Report

12/1975 (NSEB 01:03) White steam seen during clear weather

White steam was noted on 18 December (1200), 23 December (0900), and 27 December (0900).

Information Contacts: P. Sventek, USAF, Cold Bay.
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01/1976 (NSEB 01:04) White steam again seen during clear weather

White steam was noted at Shishaldin on 4-5, 11-12, 29-30, and 31 January.

Information Contacts: P. Sventek, USAF, Cold Bay.
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03/1976 (NSEB 01:06) Weak intermittent steaming

Activity during March remained low.

3 March (1100-1300): Steaming intermittently.

8 March (1700): Steaming quietly.

10 March (1700): Steaming quietly.

23 March (1800): Steaming weakly.

28 March (0600-0615): Steaming intermittently.

Information Contacts: P. Sventek, USAF, Cold Bay.
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04/1976 (NSEB 01:07) Ashfall on the flanks in late April

2 April (0600): Steaming weakly, snow on cone uniformly white.

6 April (1500): Appeared to be radially covered with ash.

14 April (0800-1800): Steaming intermittently.

25 April (2200): Steaming weakly.

27 April (1110): A faint, veil-like ash cloud was observed over the volcano. Within ten minutes the cloud had disappeared, the ash having settled on the cone, which appeared to be irregularly covered with radial ash sprays. A dark black streak was observed on the NW flank, extending 5-10 km from the summit to about the 300 m level where the slope of the cone diminishes to about 20°. The volcano was observed until 1900 and no further activity was noted.

30 April (1100-1800): The cone appeared to be ash-covered. Strong S winds had blown black ash sprays, more noticeable than the day before, onto the N flank.

Information Contacts: P. Sventek, USAF, Cold Bay.
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05/1976 (NSEB 01:08) Ash observed on cone

14 May (1400): Dark ash visible on cone.

16 May (2000): Dark ash and steaming observed.

20 May (1900): NE flank from 1,600 to 2,500 m appeared to be extensively ash covered.

31 May (1100-1400): Quiet.

Information Contacts: P. Sventek, USAF, Cold Bay.
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06/1976 (NSEB 01:09) Steaming observed; flanks about 70% ash-covered

3 June (1100-1700): Volcano quiet; cone darkened by ash or exposed rock due to melted snow.

4 June (0800-2000): Steamed at irregular intervals and occasionally threw out ash that settled onto the slopes. The visible flanks appeared to be about 70% ash covered.

5 June (1400-2100): No activity noted.

6 June (1710-1730): No activity noted.

10 June (1430): Emitting black smoke intermittently. At 2000: the cone's upper 600 m, visible above the clouds, was extensively ash-covered; no activity noted.

11 June (1100-2000): Constantly emitting a weak steam plume.

12 June (0800-2000): Emitting a slight steam plume.

15 June (0500-0600, 2100): Steaming constantly.

19 June (1530): Steaming.

22 June (1300): Peak covered by recent snows. NE flank showed ashfall.

27 June (1100-1400): Entire cone from the 1,500 m level to the summit was lightly to heavily ash-covered.

28 June (1700-1730): Steaming weakly.

Information Contacts: P. Sventek, USAF, Cold Bay.
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07/1976 (NSEB 01:10) Steam emissions with occasional ash

2 July (1300-1400): Steaming steadily.

3 July (1200): Steaming weakly.

4 July (0500-2100): Steaming weakly.

6 July (1300-2100): Dark ash observed accumulating on N slope.

8 July (2100-2200): Emitting smoke and ash.

18 July (1500-2100): Steaming lightly.

23 July (1830-2100): Steaming heavily.

Information Contacts: R. Dean, USAF, Cold Bay.
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08/1976 (NSEB 01:11) Occasional steam seen during clear weather

31 July (2045-2130): No activity.

2 August (1133-1145): No activity.

3 August (0755-2130): Light steam emission that intensified after 1600, turning to "smoke" after 2015. No new accumulations of ash were noted.

4 August (0730-0755): Steady plume of light steam.

12 August (1745-1800): Heavy steam blown down the W slope by winds.

22 August (0910-1205): No activity.

30 August (0800-0930): No activity; 90% of the ash accumulation had been blown away.

Information Contacts: R. Dean, USAF, Cold Bay.
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10/1976 (NSEB 01:13) Incandescent gas jet; steam-and-ash emission

27 September (about 2025): A 1-minute burst of incandescent gas jetted from the crater and curved S. No further activity was observed during the next several hours.

28 September (0650): Shishaldin was steaming and emitting occasional ash clouds that were carried away by strong winds.

Information Contacts: R. Dean, USAF, Cold Bay.
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11/1976 (NSEB 01:14) Steaming; "smoke" bursts on 24 November

No activity was observed during October.

9 November (0842-0915): Steaming, no ash accumulation on the cone.

17 November (1040-1135): Steaming, no noticeable ash accumulation.

18 November (0816-1510): Steaming.

19 November (0716-1330): Steaming.

24 November (1505-1630): Bursts of dense "smoke" were emitted at 5-minute intervals from the summit, then moved ~100 m down the E slope.

Information Contacts: R. Dean, USAF, Cold Bay.
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03/1977 (NSEB 02:03) Light steaming seen on one day in February

12 February (0905-1120): Steaming very lightly, no ash deposits.

22-24 February: No activity. Snow not discolored.

Information Contacts: R. Dean, USAF, Cold Bay.
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02/1978 (SEAN 03:02) Large steam plume, accompanying nearby Westdahl eruption

A NOAA satellite image (figure 1) on 8 February at 1835 shows simultaneous 60-km plumes emerging from the summits of Shishaldin and Westdahl, about 50 km apart. No plume from Shishaldin is visible in images taken 8 hours earlier and 16 hours later (figure 2). No ashfall at Shishaldin can be seen in the latter image, but resolution is only 0.9 km and a light or moderate ashfall would probably not be visible.

Figure 1. Enlargement of a portion of a NOAA 5 infrared image at 1835 on 8 February 1978 (0.9-km ground resolution), showing plumes, each ~60 km long, extending SE from both Westdahl and Shishaldin. Most of the Alaska Peninsula is visible, as is the coast of Alaska NW to the entrance to Kuskokwim Bay. The gray area off the coast is pack ice. Courtesy of Jürgen Kienle and NOAA.
Figure 2. NOAA 5 satellite imagery, 5-9 February 1978, showing Unimak Island and vicinity. North orientations (arrow) are the same for each. A: (5 February 1978, 1036, infrared) Plume extends ~230 km S, rising to an estimated 8 km; black summit hot spot. B: (6 February 1978, 1141, infrared) Plume extends ~110 km SE; black summit hot spot. C: (7 February 1978, 1101, infrared) Plume at least 6 km high and ~160 km long, blown primarily SSE but some eastward shearing evident, probably by lower altitude winds. D: (8 February 1978, 1018, infrared) Plume extends 80 km SSE, at lower altitude than in C. E: (8 February 1978, 1018, visible, enlarged ~50% more than A-D) Weak plume curves SW to W about 100 km. Shishaldin is no longer active, 16 hours after its plume was visible in figure 1. The dark triangular area S of Westdahl is fresh ashfall, subtending an angle of about 95° and covering an area of ~300 km2. No ashfall is visible on Shishaldin. Courtesy of Jürgen Kienle and NOAA.

Information Contacts: J. Kienle, Univ. of Alaska.
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02/1979 (SEAN 04:02) Ash emission increases

Peninsula Airways pilots reported unusually strong ash emission during overflights on 14 or 15, and 27 February. Ashfall, usually confined to the summit area, was occurring on the upper half of the volcano.

Information Contacts: G. Morgan, Peninsula Airways.
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09/1981 (SEAN 06:09) Plumes accompany eruption at nearby Pavlof

Activity accompanied some of the eruption at Pavlof (about 150 km ENE) [see 6:9 Pavlof; Pavlof and Shishaldin are in different time zones]. At 1315 on 25 September, NOAA weather satellite imagery revealed plumes emerging from both Shishaldin and Pavlof (Pavlof was also emitting a plume 4 hours earlier when weather clouds had last allowed a clear view of the area). By 1445, Shishaldin's plume had reached an altitude estimated at 6-7.5 km based on cloud top temperatures calculated from infrared imagery. The plume remained evident on the imagery until 1845, drifting E.

However, no activity from Shishaldin accompanied the ejection of a new cloud from Pavlof at 1845. Satellite images next showed a plume from Shishaldin at 0830 the next morning, when plumes from both volcanoes could be seen drifting ESE. On the next image with clear visibility, at 1315, no activity could be seen from Shishaldin. Reports from pilots through this period were very sketchy, but Shishaldin was said to be "steaming hard." No unusual activity was observed after 26 September by pilots or on satellite imagery.

Information Contacts: T. Miller and J. Riehle, USGS, Anchorage; S. McNutt and E. Hauksson, LDGO; W. Younker, NOAA/NESS, Anchorage.
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04/1986 (SEAN 11:04) Increased steam and ash emission

Anomalously large steam plumes with traces of ash have been noted for the past several months at Shishaldin by airline pilots and passengers. Diffuse ash layers extended from the volcano on 19 and 28 March, and steam and ash emission was seen on 6-7 May. Activity was less intense the next day, and had declined to minor steaming by 10 and 13 May. [See also 11:05].

Information Contacts: J. Reeder, ADGGS.
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05/1986 (SEAN 11:05) Steam plumes with some ash

The following supplements the preliminary report in 11:04. Large steam plumes that sometimes contained a little ash have been observed at Shishaldin since mid-March. The most vigorous activity was reported on 7 May, when a gray plume with streaks of dark ash extended 130 km S of the volcano at 3.6 km altitude. Moderate steaming was continuing in early June.

On 19 March at about 1325, James Dickson saw a yellow-brown wispy plume rise about 90 m. A nearly transparent brownish layer that extended SW was visible for more than 50 km. MarkAir captain Jerry Chisum noted another ash layer from Shishaldin on 28 March. He reported that the volcano is usually steaming from the summit, but several times in the past several months he noticed anomalously large steam plumes with traces of ash.

Chisum and several other pilots observed larger-than-normal steam and ash emission from Shishaldin on 6 and 7 May. On both days (at 1320) the plume rose at about a 45° angle to 3,400 m altitude (550 m above the summit) then drifted horizontally for at least 25 km. On 6 May the plume emission was continuous, but on the 7th the plume was puffing roughly every 20 minutes. Reeve Aleutian Airways captain Lee Goch flew within 25 km of the volcano on 6 May at 1350, noting that the plume appeared to contain traces of ash as it was pale gray. His photograph showed that the plume had drifted at least 40 km NE at about 3,600 m altitude. On 7 May at about 1300, Aleutian Air pilot Thomas Madsen observed a plume extending at least 130 km S at about 3,600 m altitude. The plume was distinctly gray with some streaks of dark ash. Less intense activity was reported by both Madsen and Goch on 8 May, when Madsen saw a grayish-white plume that drifted E. On 10 May, Reeve Aleutian captain Edward Livingston observed only minor steaming. Similar activity, with none of the steam rising above the summit, was seen by Goch on 13 May. Two days later, he saw a 90-m plume that drifted ~4 km NE.

On 6 June at 1350, Livingston saw a white steam plume that rose 1100 m above the summit. The next day at the same time, the plume was 1400 m high; both drifted a few kilometers SE. On 9 June at 1340, the plume was only 180 m high but drifted 40 km E. Goch noted only minor summit steaming on 10 June.

Information Contacts: J. Reeder, ADGGS.
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08/1986 (SEAN 11:08) Large steam plumes with some ash

Emission of large steam plumes, sometimes containing ash, were observed from aircraft and boats through August 1986. [The following reports describing activity at Shishaldin during 30 June-21 August 1986, were collected by John Reeder. Observers were Capt. Lee Goch (LG), Reeve Aleutian Airways; Capt. Jerry Chisum (JC), MarkAir; Jason Currier (JCu), on MarkAir flight; Theresa Dubber (TD) and Robert Senimore (RS), FAA, Cold Bay; and Tom Kizzia (TK), Anchorage Daily News aboard Alaska state ferry Tustumena.]

30 June (1900): White steam plume, drifting at least 5 km S. (LG)

19 July (1430): White steam plume with minor ash to 550 m above the summit, drifting more than 40 km E. (LG)

Mid-July: Steam with some ash drifted substantial distances. (JC)

20 August (1345): Voluminous steam with traces of ash. (JCu)

21 August (0900): 450-m white plume drifting SSE. (TD and RS)

21 August (afternoon): White plume to at least 450 m above the summit, drifting S at least 16 km. (TK)

Information Contacts: J. Reeder, ADGGS.
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09/1986 (SEAN 11:09) Steam and ash emission

Steam plumes that sometimes contained ash were observed by airplane pilots in early October 1986. [The following reports describing activity at Shishaldin during 2-10 October 1986 were collected by John Reeder. Observers were Capts. Jerry Chisum (JC) and Clint Schoenleber (CS), MarkAir; Stephanie Madsen (SM), Aleutian Air; Capts. Harold Black (HB), Lee Goch (LG), and James Fredenhagen (JF), Reeve Aleutian Airways; and John Reeder, ADDGS (JR).]

2 October (AM and PM): Above-average steam explosions with minor ash. (JC)

2 October (1145): Steam plume with minor ash extending at least 15 km SW. (SM)

3 October (1330-1336): Narrow steam plume to 400 m height; thin steam-and-ash plume drifted more than 40 km ESE; anomalous steam puffs with minor ash noted by JR at 1331-1332 and 1336. (HB, JR)

4 October (1520): Steam explosions sent plume to 800 m above the volcano; plume of vapor and minor ash extended about 50 km SSE; small amounts of black ash coated snow on N and NW flanks. (LG, JF, JR)

8 October: Normal 50-m steam plume. (CS)

10 October: Normal 50-m steam plume. (CS)

Information Contacts: J. Reeder, ADGGS.
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12/1986 (SEAN 11:12) Vigorous steam ejection

Vigorous steam ejection was observed on 20 December, and weak to moderate steaming was occasionally visible from late October through late December 1986. The 20 December steam ejection was considerably stronger than Shishaldin's typical activity, but significantly weaker in both size and ash content than the 6-7 May steam and ash emission. [The following reports describing activity at Shishaldin during 27 October-26 December 1986 were collected by John Reeder. Observers were Capts. Jerry Chisum (JC), MarkAir; Capts. Harold Black (HB) and Edward Livingston (EL), Reeve Aleutian Airways; Marcia Brown (MB), FAA, Cold Bay; Capt. Harold Wilson (HW), Peninsula Airways; and Rick Cales (RC), Cold Bay.]

27 October: Steam plume and haze to 80 km SW. (HB, EL)

17 November (1200-1400): Small steam plume to 20 km S; haze to 70 km S. (JC, EL)

18 November: Steam plume and haze to 65 km SW. (JC)

25 November: Unusual volume of steam, drifting ENE. (MB)

2 December: Very little steam (30-m plume). (MB)

15 December (1400): 300-m steam plume. (HW)

20 December (1030): Steam puffs to 600 m above the volcano. (HW)

20 December (1230): Steam blast rose to 2 km above summit in 10 minutes, remaining for 1 hour before slowly subsiding. (HW)

26 December (1800): 300-m vertical steam plume, drifting 8 km NE. (RC)

27-29 December: 300-m vertical steam plume. (MB)

Information Contacts: J. Reeder, ADGGS.
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02/1987 (SEAN 12:02) Small ash eruption followed by steaming

On 15 February at 1600, Marsha Brown observed a large dark-gray plume rising at least 600 m above the summit, drifting ENE. The plume had not been evident 2 hours earlier and lasted until at least 1830. Larger-than-average steam plumes were later observed on 21 and 26 February and 3 March. [The following reports describing activity at Shishaldin during 15 February-3 March 1987 were collected by John Reeder. Observers were Marsha Brown (MB) and Theresa Dubber (TD), FAA, Cold Bay; and Andy Livingston (AL), Don Munson (DM), and Lee Goch (LG), Reeve Aleutian Airways.]

15 February (1600): 600-m-high plume to the ENE. (MB)

21 February (1314): 150-m-high plume to the NE. (JF, AL)

26 February (0925): 300-m-high plume to the SW. (TD)

2 March (1254): Minor steam to the SW. (JF, DM)

3 March (1240): 300-m-high plume extending 20 km ENE. (LG)

Information Contacts: J. Reeder, ADGGS.
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10/1993 (BGVN 18:10) Steam plume observed rising to 1,800 m above the summit

A steam plume up to 1,800 m above the volcano was reported by pilots on 28 October. That same day, observers from Izembeck National Wildlife Refuge reported a steam-and-ash plume that rose to 1,200 m above the summit and drifted SE.

Information Contacts: Alaska Volcano Observatory.
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05/1995 (BGVN 20:05) Large steam plume

On 16 May a steam plume rose ~1,500 m above Shishaldin. Although large compared to typical day-to-day emissions, this is not unusual.

Information Contacts: Alaska Volcano Observatory.
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12/1995 (BGVN 20:11) Eruption sends ash plume above 10 km altitude

Based on satellite imagery and pilot reports received by the U.S. Federal Aviation Administration, an eruption began at 1830 on 23 December. Between 1830 and 2000 on 23 December, pilots reported an ash plume as high as 10.5 km altitude (35,000 feet); prevailing winds carried the plume primarily N and NW. Analysis of a satellite image from 1912 showed a possible small ash plume extending ~50 km NW. Possible very light ashfall was reported at approximately 0130 on 24 December in Cold Bay, 90 km NE; this ash would have been carried by westerly low-altitude winds.

Information Contacts: Alaska Volcano Observatory.
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01/1996 (BGVN 21:01) Steam plumes; thermal anomaly on satellite images

An eruption on 23 December was first reported by pilots who observed an ash plume as high as 10.5 km altitude (BGVN 20:11/12). Possible very light ashfall was reported a few hours later 90 km away. Large steam plumes were reported in early January, and an intermittent "hot spot" was detected on AVHRR satellite imagery during 5-26 January, in the vicinity of the summit crater. This thermal anomaly may reflect unusually high temperatures in the vicinity of the continuously active fumaroles in the summit crater. AVO received no additional pilot reports or other observations of eruptive activity after 26 January.

Information Contacts: Alaska Volcano Observatory.
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09/1997 (BGVN 22:09) Small steam-and-ash plume on 2 June

A visual observation of a small steam-and-ash plume was made by the U.S. National Weather Service at 1535 on 2 June from Cold Bay (90 km NE); the plume rose 300-450 m above the summit and drifted ~8 km downwind to the N. Installation of a seismic network of six stations was completed in July; testing and data collection to determine background seismicity is expected to be completed by mid-November.

Information Contacts: Alaska Volcano Observatory.
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02/1999 (BGVN 24:02) Steam plumes and thermal activity seen at summit

During the first week of February, National Weather Service personnel in Cold Bay, 93 km ENE of Shishaldin, observed anomalous steaming. On 9 February a vigorous steam plume rose as high as 1,830 m above the vent and a long plume drifted downwind. Satellite imagery taken that day showed a thermal anomaly at the vent in addition to the steam plume. The steam activity decreased during the week, becoming only light puffs rising a few meters above the vent; however, the thermal anomaly at the vent persisted. A newly installed seismic net recorded slightly elevated seismicity beginning at the end of January.

The hazard status was raised to Yellow on 18 February due to the persistence of the thermal anomaly and the identification of low-level seismic tremor. Pilots and ground observers reported a large steam plume rising to 5,800 m on 18 February. No ash was detected on satellite imagery. Cloudy weather precluded ground observations for most of the following week.

Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetrical cone with a basal diameter of approximately 16 km. A small summit crater typically emits a noticeable steam plume with occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, situated near that part of the arc where the maximum rate of subduction occurs. It has erupted at least 27 times since 1775. Major explosive eruptions occurred in 1830 and 1932, and eight historical eruptions have produced lava flows. Steam and minor ash emission began in March 1986 and continued intermittently through mid-February, 1987. A poorly documented short-lived eruption of steam and ash, perhaps as high as 10 km, occurred in December 1995 (BGVN 21:01). Fresh ash was noted on the upper flanks and crater rim but no specific eruptive event was identified for the deposits.

Information Contacts: Alaska Volcano Observatory, a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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03/1999 (BGVN 24:03) Increased shallow seismicity precede April Strombolian eruptions

Low-level seismicity and a thermal anomaly visible in satellite imagery continued at Shishaldin during March, preceding Strombolian eruptions on 17 April. On many days no observations were obtained due to bad weather.

A new seismic net at Shishaldin recorded elevated seismicity beginning near the end of January. On 9 February a thermal anomaly appeared on satellite imagery and vigorous steam plumes were reported through the next week (BGVN 24:02). No ash was detected on the satellite imagery. Low-level tremor prompted the Alaska Volcano Observatory (AVO) to raise the Level of Concern Color Code to Yellow on 18 February. The tremor subsequently diminished, but seismicity remained above normal.

National Weather Service observers in Cold Bay, 90 km NE, reported that no steam plume was present during the first week of March, but that the upper summit was snow-free. Apparently, heating in the summit area caused the snow to melt. A shallow M 5.0 earthquake ~14 km SW of Shishaldin on 4 March was followed by hundreds of small aftershocks that persisted until late in the month.

Seismic activity, chiefly strong tremor, substantially increased above previous levels at 0800 on 7 April, causing AVO to raise the hazard status to Orange. Weather in the area was overcast with haze, preventing views of the summit area. The strong tremor declined by the afternoon and returned to previous levels. Tremor remained steady from 8 April without significant changes through 12 April, when the hazard status was decreased to Yellow. The thermal anomaly observed in satellite imagery persisted.

On 12 April a M 4.5 earthquake struck W of the volcano; aftershocks followed. Tremor increased markedly late on 13 April. This tremor episode lasted over one day and decreased somewhat for the next three days. AVO again raised the hazard status to Orange on 14 April.

AVO staff flying with Alaska State Troopers saw a minor Strombolian eruption at 1700 on 17 April. Incandescent blocks and spatter rose as high as 200 m above the vent, but at that time no lava had come over the crater rim. On the morning of 18 April, National Weather Service observers NW of the volcano both in Cold Bay and on a ship saw incandescent lava at the summit and snow melt running down the NW flank. A small steam plume with little or no ash developed as hot lava contacted snow at the summit. Tremor remained elevated.

On 19 April at 1145 a pilot saw a steam-and-ash plume that reached ~9 km altitude. In accord with this observation, tremor amplitudes increased dramatically after 1133 in the wake of a steady, two-day tremor increase. Observers interpreted these as signs of a significant eruption and raised the hazard status to Red. By early afternoon the eruption column reached at least 13.7 km altitude. The eruption lasted about 7 hours with one ash plume at higher elevations moving N and another, at lower elevations, S. Aviation warnings ("Graphic Volcanic Meteorological Impact Statements") for 0410-1610 on 19 April indicated two separate areas to avoid; one area spread ~300 km N over an elliptically shaped zone and the other, ~500 km S over a broadly spreading pattern that also included a lobe reaching ~375 km NW of Shishaldin (to Chignik). Late on the night of 19 April seismic tremor decreased substantially, but the Strombolian eruption continued at moderate levels.

On 20 April at about 0345, seismicity abruptly and significantly declined, indicating that explosive activity had subsided; still, satellite imagery after 0650 (1450 GMT) revealed a summit-crater thermal anomaly. Authorities decreased the hazard status to Orange. Seismic activity increased again about 1600. The increase in seismicity strengthened at about 2300 and on the morning of 21 April reached levels similar to those recorded in the hours before the explosive eruption on 19 April, and the hazard status returned to Red. Moderate Strombolian eruptions were thought to be occurring, though at the time satellite imagery failed to show a major ash cloud.

A moderate Strombolian eruption occurred through the night of 21 April. Seismicity became elevated and a very large thermal anomaly became visible on satellite imagery. Lava fountains shot tens of meters above the summit and satellite imagery indicated occasional steam and clouds of sparse ash extending for less than 50 km at altitudes under 5,000 m.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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04/1999 (BGVN 24:04) Steam-and-ash plume on 19 April rose to 15-20 km and was carried to great distances

Strombolian eruptions, including forceful steam-and-ash plumes, peaked at Shishaldin on 19 April (BGVN 24:03) and continued well into May. The 19 April plume rose to 15-20 km and various components were carried in different directions (figure 3). As discussed further in the Atmospheric Effects section below, scientists studying atmospheric aerosols with a variety of satellite-based instruments as well as ground-based lidar detected atmospheric anomalies through at least late May; some at great distances from the volcano. The initial anomalies seen by satellite were clearly linked to the 19 April eruption, but at longer time intervals after the eruption and at greater distances from the source, this became less certain.

Figure 3. Detailed view of the spreading eruption cloud from Shishaldin on 19 April, taken from a series of images taken by the GOES 10 satellite (channel 1). Unimak Island is outlined. The top frame was imaged at 1200; the following frames at subsequent half-hour increments. The cloud labeled "A" was at higher altitude and moved N; cloud "B" was at lower altitude and moved S. Courtesy of NOAA/NESDIS.

Moderate Strombolian eruptions and elevated seismicity continued following the initial forceful eruption and through the night of 22 April, . Lava fountaining to about 150 m above the summit coincided with satellite images of occasional steam and sparse ash clouds. These clouds extended ~48 km at altitudes less than 4.6 km. Satellite data during the first week of May showed a few small ash-poor plumes, but no thermal anomalies or other indicators of significant eruptive activity were seen.

The next significant reported event, on 13 May, occurred after a night with a small thermal anomaly in satellite imagery and weak tremor. The crew of a National Weather Service boat at the N end of False Pass, 30 km NE from the volcano, saw three puffs at ~1025. A plume rose 300 m above the summit. A pilot's report at 1155 confirmed the activity. Poor weather conditions may have thwarted observers' ability to see eruptive activity the following week and none was reported. At 2311 on 24 May a pilot reported a plume that rose to 6.1 km. Ash-rich steam in a plume was visible in satellite imagery at 1459 on 25 May, extending 160 km S from Shishaldin at an estimated altitude of ~4.6 km.

One of the most active volcanoes of the Aleutian Islands, the glacier-covered Shishaldin lies at the westernmost end of three large stratovolcanoes on the eastern half of Unimak Island. The volcano's frequent explosive activity has primarily consisted of Strombolian ash eruptions vented from its small summit crater, and occasional lava flows. The historical record of such events goes back to the 18th century.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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; NOAA/NESDIS Operational Significant Event Imagery Support Team, Interactive Processing Branch E/SP22, 5200 Auth Road, Camp Springs, MD 20746, USA (URL: http://www.osei.noaa.gov/).
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08/1999 (BGVN 24:08) Eruption ends after long ash plumes are emitted in late May

The eruption that began in mid-April (BGVN 24:03 and 24:04) ended in late May following blasts that sent ash plumes to 6 km altitude. No eruptive activity was observed or reported the week of 15-21 May, but the hazard status remained at Yellow due to persistent low-level seismicity and a summit thermal anomaly. A pilot report at 2311 on 24 May indicated an eruption plume up to 6 km altitude. A narrow ash-rich plume was seen in satellite imagery at 0659 on 25 May, extending about 160 km S from Shishaldin at an estimated altitude of 4.5 km. Following these observations the hazard status was raised to Orange, indicating that the volcano was in eruption. The plume continued to be seen on imagery at 1530, extending 175 km S, with low to moderate levels of seismicity being recorded.

Satellite imagery at 1000 on 26 May indicated that a narrow ash-rich plume continued to be emitted from the volcano, extending ~110 km SE at altitudes of up to 6 km; a pilot report at 1603 on 25 May indicated an ash-rich plume at ~5.5 km altitude. The plume seen on satellite imagery at 1645 extended at least 160 km ESE. Seismicity was at low to moderate levels beneath the volcano. Satellite imagery during the night of 26-27 May showed a continuous narrow ash-rich plume extending ~800 km ESE from the volcano at altitudes of 4.5-6 km until about 0100 on 27 May. After that time the plume became detached from the volcano and had diminished significantly by 0300. A small thermal anomaly in the summit crater was visible in a satellite image at 0908. A ground crew from AVO on the N flank of the volcano reported only white steam from the summit crater during 28 May.

Seismicity remained low through 1 June, and although the top of the volcano was visible no ash plume or thermal anomaly was seen in satellite imagery. The Level of Concern Color Code was therefore downgraded to Yellow. Although low-level seismicity continued, on 18 June AVO lowered the Level of Concern Color Code to Green based on the decline in activity over the previous month.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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02/2000 (BGVN 25:02) Small phreatic explosions during September 1999-January 2000

The Alaska Volcano Observatory (AVO) reported on 21 January 2000 that investigations of recent seismic data had revealed evidence for small explosions at Shishaldin. Later detailed study of the seismic records showed that the activity may have begun in as early as late September. The numbers of explosions varied from several to over 200/day, but no steam or ash plumes were observed by airborne or ground observers. Also, no thermal anomaly was observed in satellite imagery, indicating that lava had not reached the surface. It was thought that the explosions were phreatic, caused by the flashing of water to steam; these events may represent a local hazard within a few hundred meters of the vent but do not pose a hazard to aircraft. Small explosions continued at a similar rate through 28 January.

Small low-frequency seismic events, present at Shishaldin since June 1999, gradually increased in amplitude after 28 January, with a noticeable increase during 2-3 February. Seismic data continued to show the presence of small phreatic explosions. Reports of steam plumes were received during the week ending on 2 February, with heights reaching as high as ~900 m above the summit. However, no thermal anomaly was observed in satellite imagery and no seismic tremor was identified; both were seen prior to the last eruptive episode in April and May 1999 (BGVN 24:03, 24:04, 24:08). Due to the increased activity, AVO raised the Level of Concern Color Code to Yellow on 3 February, indicating that the volcano is restless and an eruption may occur.

No appreciable number of seismic events were detected after 4 February; that was also the last day that small explosions were observed. Small low-frequency seismic events continued through 11 February, but at a slower rate and slightly lower amplitude. By 18 February seismic activity had declined significantly with no thermal anomalies or observations of unusual activity, so the hazard status was changed back to Green, indicating normal seismicity and surface activity.

Small low-frequency seismic events and very low-level tremor was recorded through 3 March, although at or below the levels observed in the months prior to the 19 April 1999 eruption. Low-level seismicity continued through the end of March. Vigorous steaming was reported in the second half of March, but no thermal anomaly observed in satellite imagery.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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08/2000 (BGVN 25:08) Thermal anomaly and small explosions on 11 August

The Alaska Volcano Observatory (AVO) reported on 11 August that recent satellite data indicated a weak thermal anomaly at Shishaldin's summit, although no known seismic activity occurred above background levels in the area. Pilot reports did not disclose any noticeable change in steam emission from the summit crater. Accordingly, the AVO decided to keep the Level of Concern Color Code for Shishaldin at Green.

After 11 August, clear days allowed unobstructed remote sensing, and satellite observations, which suggested no further thermal anomaly. On 18 August, AVO issued an update stating that new seismic data analysis showed several small explosions occurring coeval with the thermal anomaly reported on 11 August. These explosions were similar to those observed throughout 1999 and in early 2000 (BGVN 24:02-24:04, 24:08, and 25:02). The thermal anomaly and seismic disturbances did not recur in the remainder of August, however, so the hazard status remained Green.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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05/2002 (BGVN 27:05) Seismicity increases briefly during mid-May 2002

During mid-May 2002, the Alaska Volcano Observatory (AVO) detected an increase in background seismicity at Shishaldin that lasted for about one week. There was an increase in the number of located shallow low-frequency earthquakes and several 2-3-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"). The last reported activity at Shishaldin included a thermal anomaly and small explosions during August 2000 (BGVN 25:08).

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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06/2004 (BGVN 29:06) Seismic unrest and modest ash plumes in 2004

The last report on Shishaldin (BGVN 27:05) described an increase in backround seismicity in mid-May 2002. Specifically, there was an increase in shallow low-frequency earthquakes and several tremor-like signals. However, because there were no thermal anomolies visible on satellite imagery, and no reports of anomalous volcanic activity, Shishaldin remained at Concern Color Code Green.

Activity during August 2002. On 16 August 2002, the Alaska Volcano Observatory (AVO) received notification of a pilot report, via the National Weather Service (NWS) Alaska Aviation Weather Unit (AAWU), of volcanic activity. The pilot report indicated that Shishaldin appeared to be erupting, producing steam and dark clouds to 3.2 km altitude that moved to the NW-SE. A NWS observer in Cold Bay, ~ 100 km E of the volcano, reported a steam-rich plume coming from Shishaldin. As per operating policy, the AAWU issued an "eruption SIGMET" advising the aviation community of the possibility of airborne volcanic ash. Upon receiving the pilot report, the AVO immediately analyzed seismic and satellite data and determined that Shishaldin was at a normal background state and had not erupted. Further discussions with the observer in Cold Bay indicated that the steam plume was not uncommon. The last significant ash-producing eruptions of Shishaldin occurred during April-May 1999. Since that time, low-frequency seismic events and occasional steam plumes have characterized activity at the volcano. Shishaldin remained at Concern Color Code Green.

Activity during April-May 2004. The AVO raised the Concern Color Code at Shishaldin from Green to Yellow on 3 May due to unusual seismicity during the previous week. Seismicity changed from discrete earthquakes to more continuous ones, and 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. Satellite data showed no significant increase in ground temperature, 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.

Seismic unrest continued during 30 April to 7 May, and 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, with weaker signals 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 observed since August 2000. AVO saw no signs that an eruption was imminent. Shishaldin remained at Concern Color Code Yellow throughout the month.

During 8-14 May seismic unrest continued, characterized by sequences of volcanic earthquakes, small explosions, and seismic tremor. A weak thermal anomaly observed at the summit on 11 May was similar to those detected occasionally since January 2004. On 16 May, a pilot reported an ash plume that rose ~ 300 m above the volcano's summit. Satellite imagery from 17 May (figure 4) showed a vigorous plume, possibly containing small amounts of ash, emanating from the summit. Seismic unrest during 14-21 May was characterized by weak seismic tremor and small explosions, and during 21-28 May also included occasional discrete low-frequency earthquakes. In addition, small explosion signals were recorded by a pressure sensor. Meteorological clouds obscured views of the volcano. Satellite data acquired at 0823 UTC (0023 ADT) on 29 May showed that the crater to continue to be warmer than background temperatures.

Figure 4. Shishaldin as depicted by an ASTER false color (image with bands 3, 2, and 1 as RGB and cloud/plume detail added with a semi-transparent band 4) taken 17 May 2004. The summit crater is shrouded by clouds, but a small plume that appears to contain ash is blowing toward the N. Dark streaks on the northern flanks may be partly from a light dusting of ash; however, other dark streaks appear as darker features melting through the snow. Courtesy of AVO.

Activity during June-July 2004. Seismic unrest continued during 18 June-2 July, characterized by weak seismic tremor and occasional discrete low-frequency earthquakes. At roughly 0800 ADT on 24 June, pilots reported steam rising at least 100 m above Shishaldin's cone. Around that time, a possible weak thermal anomaly was visible on satellite imagery. Shishaldin remained at Concern Color Code Yellow.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.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.
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08/2008 (BGVN 33:08) Pilot report of ash plume in February 2008

Previously reported activity at Shishaldin included the onset of tremor and some unusual earthquakes. For at least one day in July 2004 small ash plumes rose above the summit (BGVN 29:06).

In 2008, only one instance of an ash plume was reported. According to the Anchorage VAAC a pilot reported a small ash plume at an altitude of 3 km on 12 February. The ash plume was not confirmed by satellite imagery or ground observations. AVO did not report any unusual activity during this time. Shishaldin typically emits a relatively steady steam plume, as seen on 2 September 2008 (figure 5).

Figure 5. Shishaldin and a steam plume at sunset taken from a helicopter on 2 September 2008. Image courtesy of Cyrus Read and Alaska Volcano Observatory / U.S. Geological Survey.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA; Anchorage Volcanic Ash Advisory Center (VAAC), Alaska Aviation Weather Unit, NWS NOAA US Dept of Commerce, 6930 Sand Lake Road, Anchorage, AK 99502-1845, USA (URL: http://www.ssd.noaa.gov/).
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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, it 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. There are 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.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2014 Feb 7 2014 Oct 26 (continuing) Confirmed 1 Historical Observations
[ 2008 Feb 12 ] [ 2008 Feb 12 ] Uncertain 1  
2004 Feb 17 2004 Jul (in or after) Confirmed 2 Historical Observations
[ 2000 Aug 11 ] [ Unknown ] Uncertain    
[ 1999 Sep 25 ± 5 days ] [ 2000 Feb 4 (?) ] Uncertain    
1999 Mar 13 1999 May 27 Confirmed 3 Historical Observations
1998 Nov 4 1998 Nov 4 Confirmed 1 Historical Observations
1997 Jun 2 1997 Jun 2 Confirmed 1 Historical Observations
1995 Dec 23 1996 May 16 (in or before) Confirmed 3 Historical Observations
1993 Sep 4 1993 Oct 29 Confirmed 2 Historical Observations
1986 Mar 19 1987 Feb 15 (?) Confirmed 2 Historical Observations
[ 1981 Sep 25 ] [ Unknown ] Uncertain    
1979 Feb Unknown Confirmed 2 Historical Observations
1978 Feb 8 1978 Feb 9 (?) Confirmed 2 Historical Observations
1976 Jan 1976 Sep 28 Confirmed 2 Historical Observations
1975 Sep 13 1975 Oct 26 ± 5 days Confirmed 2 Historical Observations
1967 Jan 28 Unknown Confirmed 2 Historical Observations
1963 Dec 28 Unknown Confirmed 2 Historical Observations
1955 Jul Unknown Confirmed 2 Historical Observations
1953 Oct 4 ± 3 days Unknown Confirmed 2 Historical Observations
1951 Apr 1951 Oct 5 ± 4 days Confirmed 2 Historical Observations
1948 Unknown Confirmed 2 Historical Observations
1946 Aug 1947 Jan Confirmed 2 Historical Observations
1932 Feb 1 1932 May 21 Confirmed 2 Historical Observations
1929 May 28 1929 Jun 23 (in or after) Confirmed 2 Historical Observations Summit and north flank
1928 Aug Unknown Confirmed 2 Historical Observations
1927 Unknown Confirmed   Historical Observations
1925 Unknown Confirmed   Historical Observations
1922 Oct 15 ± 45 days Unknown Confirmed 2 Historical Observations
[ 1912 ] [ Unknown ] Uncertain    
1901 Unknown Confirmed   Historical Observations
[ 1899 ] [ Unknown ] Uncertain    
1898 Unknown Confirmed 2 Historical Observations
[ 1897 ] [ Unknown ] Uncertain    
1883 Unknown Confirmed 2 Historical Observations
[ 1880 ] [ 1881 ] Uncertain    
[ 1865 ] [ Unknown ] Uncertain    
1842 Unknown Confirmed 2 Historical Observations
1838 Unknown Confirmed 2 Historical Observations
1830 Nov 1830 Dec Confirmed 3 Historical Observations
1827 1829 Confirmed 2 Historical Observations
1826 Unknown Confirmed 0 Historical Observations
1825 Unknown Confirmed 2 Historical Observations NE flank (1300 m)
1824 Unknown Confirmed 3 Historical Observations
[ 1790 ] [ Unknown ] Uncertain    
[ 1775 ] [ 1778 ] Uncertain    
0950 (?) Unknown Confirmed   Radiocarbon (uncorrected)
7050 BCE (?) Unknown Confirmed   Radiocarbon (uncorrected)
7550 BCE (?) Unknown Confirmed   Radiocarbon (uncorrected)

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

Agajedan | Sisquk | Chichaldinskoi | Shushaldinskaya | Sisaguk | Fernandez, Volcano de | Caroli (?) | Smoking Moses | Moses | Sissagjuk

Cones

Feature Name Feature Type Elevation Latitude Longitude
Olive, Mount Cone
Three prominent volcanoes are constructed along an E-W line on the eastern half of Unimak Island. The aptly named Roundtop volcano in the lower foreground is glacially eroded and has had no historical eruptive activity. In the 1930s warm springs were found on its slopes. The recent discovery of Holocene pyroclastic-flow deposits and a group of lava domes south of Roundtop indicate it is still an active volcano. The glacially dissected Isanotski volcano and the beautifully symmetrical Shishaldin volcano are the prominent peaks behind Roundtop.

Photo by Clayton and Marcia Brown, 1986 (courtesy of John Reeder, Alaska Div. Geology Geophysical Surveys).
Three prominent stratovolcanoes are constructed along an E-W line on Unimak Island. Steaming Shishaldin, the highest of the three, rises to 2857 m in the foreground and is one of the most active volcanoes in the Aleutians. The dissected Isanotski volcano (right) has had reported eruptions of uncertain validity, and Roundtop volcano (center distance) has had Holocene eruptions, but no historical activity.

Photo by Clayton and Marcia Brown, 1987 (courtesy of John Reeder, Alaska Div. Geology & Geophysical Surveys).
This closeup aerial view of the summit of Shishaldin volcano shows its almost constantly steaming crater, with its high point on the south rim. Progromnoi volcano, part of the Westdahl volcanic complex at the western end of Unimak Island, forms the sharp-topped peak in the left distance.

Photo Clayton and Marcia Brown, 1987 (courtesy of John Reeder, Alaska Div. Geology & Geophysical Surveys).
Often compared to Mount Fuji of Japan, the symmetrical Shishaldin volcano, located on central Unimak Island in the Aleutians, rises 2857 m above sea level. The volcano has a summit crater that emits a nearly continuous plume of steam. Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. It has produced frequent strombolian eruptions, sometimes with lava flows, since the 18th century.

Photo by Chris Nye (Alaska Division of Geological & Geophysical Surveys, Alaska Volcano Observatory).

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

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.

Volcano Types

Stratovolcano
Pyroclastic cone(s)
Maar(s)
Tuff cone(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Basalt / Picro-Basalt
Andesite / Basaltic Andesite
Minor
Dacite
Trachyte / Trachyandesite
Rhyolite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
0
0
10
197

Affiliated Databases

Large Eruptions of Shishaldin 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).
WOVOdat 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.
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).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.