The Alaska Volcano Observatory says a small explosion at Cleveland Volcano in the Aleutian Islands may have sent up a small ash cloud.
Clouds prevented satellite observation of an ash cloud.
The observatory says the explosion at 1:12 p.m. Wednesday was of short duration and similar to small events in December. Those explosions created ash clouds that dissipated quickly and did not affect air traffic.
Cleveland Volcano is a 5,675-foot peak on an uninhabited island 940 miles southwest of Anchorage.
Scientists detected the explosion on distant infrasound seismic networks. Infrasound refers to frequencies below what can be heard by the human ear.
Scientists say that if a larger explosion occurs that sends ash more than 20,000 feet high, the eruption should be detected by seismic, infrasound or lightning networks.