USGS Alaska Volcano Observatory
Founded in 1988, the Alaska Volcano Observatory monitors, assesses and dispenses information about the Alaskan volcanoes.
People have been recording Alaskan volcanic activity since approximately 1760. As of 2009, the largest volcanic eruption in Alaska's historical time period was Novarupta/Katmai in 1912.
In 2008, the Alaskan Volcano Observatory was capable of monitoring more than 30 volcanoes with 200 seismic stations.
The Aleutian Arc contains the majority of the Alaskan volcanoes. Approximately 80 volcanoes are located in the 1,550-mile-long Aleutian Arc.
Since 1760, there have been approximately 27 volcanoes in Alaska with 230 confirmed eruptions. However, there are more than 400 unconfirmed possible eruptions from 50 additional volcanoes.