Printer friendly versionAVO/USGS Volcanic Activity Notice
Current Volcano Alert Level: ADVISORY
Previous Volcano Alert Level: WATCH
Current Aviation Color Code: YELLOW
Previous Aviation Color Code: ORANGE
Wednesday, September 18, 2019, 1:10 PM AKDT
Alaska Volcano Observatory
N 51 deg 55 min E 179 deg 35 min
2625 ft (800 m)
Volcanic Activity Summary: Seismicity at Semisopochnoi has decreased over the past few weeks with no observations of seismic tremor since September 15. Low-level sulfur dioxide emissions continue to be observed when conditions permit. Other than the ongoing refilling of the crater lake, no changes in surface features have been observed since the small, shallow cone that formed around August 24. Due to the decrease in activity, AVO is lowering the color code/activity level to YELLOW/ADVISORY.
[Volcanic cloud height] No cloud observed
[Other volcanic cloud information] No cloud observed
Semisopochnoi is monitored with an on-island seismic network, and remotely by satellite and lightning sensors. An infrasound array on Adak Island could detect explosive emissions from Semisopochnoi with a 13 minute delay if atmospheric conditions permit.
Michelle Coombs, Scientist-in-Charge, USGS
email@example.com (907) 786-7497
David Fee, Coordinating Scientist, UAFGI
firstname.lastname@example.org (907) 322-4085
A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at
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.