A volcanic eruption, preceded by a swarm of magnitude 3.0 to 5.8 earthquakes, was first observed at 2217 UTC (1417 AKDT) on 07 August 2008, and was located at Kasatochi Volcano – 52.2N, 175.5W.

The Alaska Volcano Observatory (AVO) reported three major explosive eruptions at Kasatochi volcano between approximately 2230 UTC (1430 AKDT) on 07 August and 0500 UTC on 08 August (2100 AKDT on 07 August). Ash from these explosions reached at least 45,000 ft above sea level. According to AVO, the possibility of explosive events continues.

The volcanic eruption produced a 19-cm amplitude tsunami measured at the Adak, Alaska tide gauge at 0324 UTC on 08 August 2008. The tsunami was also recorded at Atka, Alaska with a maximum amplitude of 7 cm. These tide gages are monitored by the Tsunami Warning Centers and are maintained by NOAA�s National Ocean Service. Click on the site name below to see a graph of the tsunami. Listed wave heights are maximum amplitude in cm (above sea level). Observed arrival time is the observed tsunami arrival time in UTC. Approximate tsunami travel times from the volcano to the tide gages are 25 minutes to Adak and 34 minutes to Atka.