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USGS Volcano Notice - DOI-USGS-AVO-2023-09-23T07:37:50-08:00
Volcano: Shishaldin (VNUM #311360)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
Issued: Saturday, September 23, 2023, 12:28 PM AKDT
Source: Alaska Volcano Observatory
Notice Number: 2023/A1415
Location: N 54 deg 45 min W 163 deg 58 min
Elevation: 9373 ft (2857 m)
Area: Aleutians
Volcanic Activity Summary:
The level of unrest has increased at Shishaldin Volcano. Seismic tremor has increased significantly over the past 36 hours. No strongly elevated temperatures indicative of lava at the surface or ash emissions have accompanied the elevated seismicity at this time, although the volcano is obscured by clouds. Based on previous episodes of activity, eruptive activity in the form of lava fountaining and ash emissions is possible within hours. If geophysical or remote sensing signals intensify, the Alaska Volcano Observatory will issue further notices of volcanic activity.
Recent significant ash events during the current eruption resulted in ash clouds with heights up to 40,000 ft (12 km) above sea level. These events can occur with little warning. It is also possible that ash emissions may occur at a lower-level, steady state and be sustained for many hours. AVO is monitoring the volcano closely and will issue additional Volcanic Activity Notice’s to provide notice of significant changes in activity as they occur.
Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.
Recent Observations:
[Volcanic cloud height] None
[Other volcanic cloud information] None
Hazard Analysis:
[Pyroclastic flow] likely on the immediate flanks of the volcano
[Mud flow] likely on the immediate flanks of the volcano
Remarks:
Shishaldin Volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 10 miles (16 km). A 660 ft. (200 m) wide funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 26 confirmed eruptions since 1824. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft. (14 km) above sea level.
Contacts:
Matt Haney, Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497
David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (907) 378-5460
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.
(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA) | |
(2) Issued: | (20230923/2028Z) |
(3) Volcano: | Shishaldin (VNUM #311360) |
(4) Current Color Code: | ORANGE |
(5) Previous Color Code: | ORANGE |
(6) Source: | Alaska Volcano Observatory |
(7) Notice Number: | 2023/A1415 |
(8) Volcano Location: | N 54 deg 45 min W 163 deg 58 min |
(9) Area: | Aleutians |
(10) Summit Elevation: | 9373 ft (2857 m) |
(11) Volcanic Activity Summary: |
The level of unrest has increased at Shishaldin Volcano. Seismic tremor has increased significantly over the past 36 hours. No strongly elevated temperatures indicative of lava at the surface or ash emissions have accompanied the elevated seismicity at this time, although the volcano is obscured by clouds. Based on previous episodes of activity, eruptive activity in the form of lava fountaining and ash emissions is possible within hours. If geophysical or remote sensing signals intensify, the Alaska Volcano Observatory will issue further notices of volcanic activity. Recent significant ash events during the current eruption resulted in ash clouds with heights up to 40,000 ft (12 km) above sea level. These events can occur with little warning. It is also possible that ash emissions may occur at a lower-level, steady state and be sustained for many hours. AVO is monitoring the volcano closely and will issue additional Volcanic Activity Notice’s to provide notice of significant changes in activity as they occur. Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.
|
(12) Volcanic cloud height: | None |
(13) Other volcanic cloud information: | None |
(14) Remarks: | Shishaldin Volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 10 miles (16 km). A 660 ft. (200 m) wide funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 26 confirmed eruptions since 1824. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft. (14 km) above sea level. |
(15) Contacts: | Matt Haney, Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497 David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (907) 378-5460 |
(16) Next Notice: |