Kasatochi Activity - Color Code YELLOW : Alert Level ADVISORY

Low level seismicity at Kasatochi continues. Satellite views were mostly cloudy throughout much of the week. Clear satellite views over the last 24 hours showed a thermal anomaly, likely coming from cooling eruption deposits.

Low level seismicity at Kasatochi continues. Intermittent power outages in Adak affected AVO's seismic networks in the Kasatochi area earlier this week. Satellite views were mostly cloudy throughout much of the week. Clear satellite views Wednesday night show a thermal anomaly and a small steam plume.

Low level seismicity at Kasatochi continues. Intermittent power outages are affecting AVO's seismic networks in the Kasatochi area. Thus, we have been unable to monitor Kasatochi from the nearby networks much of this week. Satellite views were cloudy throughout the week. Views on Monday suggest a possible weak thermal anomaly.

Because of declined seismicity and lack of activity in satellite data, AVO lowered the aviation color code from ORANGE to YELLOW and the Alert Level from Watch to Advisory on September 4. Seismicity at Kasatochi volcano remained low this week. For most of the week, no activity was observed in mostly cloudy satellite views. Today, a weak thermal anomaly was observed at the volcano. On September 3 and 4, passing mariners observed vigorous steam and gas plumes rising above the crater and extending up to twenty miles downwind.

Seismic activity at Kasatochi volcano has declined significantly since the eruptions on August 7. No activity has been observed in satellite data since August 12. Therefore AVO is lowering the aviation color code from ORANGE to YELLOW and the Alert Level from Watch to Advisory.

Seismic activity at Kasatochi volcano continues to slowly decline following the eruptions on August 7. Possible intermittent tremor occurred for several hours on August 27 and was detected by the AVO seismic network on Great Sitkin Island 25 miles west of Kasatochi. Satellite views were cloudy this week.

Seismic activity at Kasatochi continues. Earthquakes were detected by the AVO seismic network on Great Sitkin Island 25 miles west of Kasatochi all week. Satellite views the majority of the week were obscured by clouds. On Sunday, August 17, people on Adak reported smelling sulfur and on Monday, August 18, clear satellite views showed a steam plume from the volcano's summit.

Eruptive activity at Kasatochi volcano has declined gradually over the past week. Seismic activity is still being detected by the AVO seismic network on Great Sitkin Island 25 miles to the west and the volcano remains in a restless condition and is still considered hazardous to approach. The volcanic ash cloud produced by the eruption last week has dissipated and is no longer detected anywhere over Alaska in satellite data. A volcanic gas and aerosol cloud from the eruption is still present over parts of North America and the North Atlantic region, but has been dispersed by the wind and no longer is a single intact cloud.

The intense seismic activity associated with the Kasatochi eruption has declined and is no longer detected on the AVO seismic network on nearby Great Sitkin Island (about 40 km (25 mi) to the east). Vigorous ash emissions (up to 35,000 feet) have not been observed in satellite data for about 36 hours and AVO has received no pilot reports of ash clouds. Passing mariners report nothing unusual and no obvious indications that an explosive eruption is in progress. It appears that explosive eruptive activity has waned and AVO is lowering the aviation color code and alert level to ORANGE/WATCH.

Three major explosive eruptions occured at Kasatochi between approximately 2200 UTC (14:00 AKDT) on 07 August and 0435 UTC on 08 August (20:35 AKDT on 07 August). Ash from these explosions reached at least 45,000 ft above sea level. Ash emissions became continuous following the last explosive event and have produced a continuous ash cloud extending for more than 500 miles in a counterclockwise spiral. Ash from this continuous phase is likely at an altitude in excess of 35,000 ft above sea level. The eruption is ongoing and additional explosive events are possible. Kasatochi Island and the general area around the island are within a hazard zone and should be avoided. Significant ash fall, pyroclastic flows and surges, and ballistic fallout may occur without warning. If the eruption intensifies and large pyroclastic flows and surges are generated, these may travel over water for tens of miles. It is also possible for these flows to initiate waves if they interact dynamically with the sea.

Satellite data show an ash plume to an altitude of at least 35,000 ft. in the vicinity of Kasatochi Volcano 22:30 UTC (14:30 ADT). The plume is drifting to the south-southwest. Based on this information, we are elevating the color code to RED/WARNING. This follows the recent increase in volcanic and earthquake activity.

Earthquake activity in the vicinity of Kasatochi Volcano continues and is now being accompanied by periods of volcanic tremor. Volcanic tremor is often associated with fluid or magma migration. This morning, a US Fish and Wildlife Service field crew on Kasatochi Island reported periods of continuous ground shaking lasting 5-10 minutes, numerous rockfalls, and strong sulfur smell. These observations combined with the elevated seismicity suggest that an eruption is more likely and AVO is raising the color code and alert level to ORANGE/WATCH.

Over the past 12 hours earthquake activity in the greater vicinity of Kasatochi volcano has increased rapidly. Earthquakes are poorly located, and it is possible that the earthquakes are associated with submarine activity. A US Fish and Wildlife Service field crew on Kasatochi Island has reported continual small tremors over the past several days. AVO is elevating the color code at Kasatochi to YELLOW due to the possibility that these earthquakes may result from magma movement toward the surface. The swarm-like character of the seismicity suggests that the activity may be related to the intrusion of magma which may or may not culminate in eruptive activity. Earthquake locations are very poor due to the lack of seismic monitoring in this area. There are no seismic instruments on Kasatochi Island and we are detecting the earthquakes on neighboring networks.