Kasatochi volcano with crater lake prior to the eruption of August 7, 2008
|Elevation||1,030 ft (314 m)|
|Prominence||1,030 ft (314 m)|
|Location||Aleutian Islands, Alaska|
|Topo map||USGS Atka C-5|
|Volcanic arc/belt||Aleutian Arc|
The summit is truncated by a large volcanic crater containing a 0.5 miles (0.8 km) wide crater lake, which was formed after a large, explosive eruption perhaps only a few hundred years ago. The surface of the saltwater lake is less than 200 ft (60 m) above sea level. Recent pictures of the volcano show that the crater lake is still present after the 2008 eruption.
August 2008 eruption
On August 7, 2008, Kasatochi began erupting explosively with an ash plume maintaining an altitude of 35,000 feet and reaching 45,000 feet. As the eruption became imminent, it forced two biologists from the U.S. Fish and Wildlife Service to evacuate the island. An ashfall advisory was issued at the time for Adak Island. Prior to 2008, the last confirmed activity at Kasatochi was in 1899, but that was not believed to be an eruption. Mild degassing was reported to the AVO in 2005, but that could not be confirmed.
Currently, there are no seismographs or web cameras on the island of Kasatochi, so scientists must rely on data from nearby Great Sitkin volcano and Adak Island (near Mount Adagdak) to obtain ongoing information on Kasatochi.
"Fortunately, the existing seismic networks on nearby volcanoes picked up the activity at Kasatochi volcano," said Tom Murray, scientist-in-charge of the Alaska Volcano Observatory (AVO). "They were installed with funding from the Federal Aviation Administration to reduce the hazard to aviation from volcanic ash. These networks were crucial in recognizing that this volcano had entered the first stage of a major eruption."
"Our hope is to have monitoring equipment on all volcanoes that pose the greatest threats to public safety," said USGS volcano scientist Marianne Guffanti. "Satellite imagery is useful to see the big picture of what is happening and what is going into the atmosphere. But direct instrumentation, such as placing seismic monitors around a volcano, will help give an early warning and give people more time to plan for hazardous events."
On October 30, 2008, the AVO lowered the alert level of Kasatochi to "UNASSIGNED", saying "Over the past 2 months, seismic activity detected on regional networks in the vicinity of Kasatochi Volcano has steadily declined in intensity. Overflights and satellite imagery show no indication of significant continuing unrest. The likelihood of resumed eruptive activity at Kasatochi has greatly diminished, therefore, we are reducing the Aviation Color Code to UNASSIGNED and Volcanic Alert Level to UNASSIGNED." 
Prior to the 2008 eruption, a Steller Sea Lion rookery was on the north half of the island. Kasatochi also supported a colony of about 250,000 Least Auklets and Crested Auklets. This large bird colony attracted also several avian predators such as peregrine falcons and bald eagles.
After the 2008 eruption the life on Kasatochi appears to have been destroyed. A research project was started in 2009 in order to study ecosystem impact and long-term recovery.
- "Kasatochi". Global Volcanism Program, Smithsonian Institution. http://www.volcano.si.edu/world/volcano.cfm?vnum=1101-13-.
- Kasatochi Island: Block 1107, Census Tract 1, Aleutians West Census Area, Alaska United States Census Bureau
|Wikimedia Commons has media related to Kasatochi Island.|
- USGS: Kasatochi volcano
- Kasatochi Island Photos Photos from Kasatochi Island, July 2008
- Alaska Volcano Observatory, Kasatochi Description and Statistics