The Alaska Volcano Observatory (AVO) said the volcano erupted around 21:04 AKDT (5:04 UTC 26 May), resulting in an ash cloud up to 15,000 feet above sea level. 

"Since that explosion, seismicity has decreased and satellite images show that the ash cloud has detached from the vent and is moving towards the east. Additional explosions are possible and the Aviation Color Code remains at RED and the Volcano Alert Level at WARNING," AVO said. 

Great Sitkin Volcano is a basaltic andesite volcano that resides on the most northern half of Great Sitkin Island and is a part of the Andreanof Islands group in the central Aleutian Islands.