Mount Cleveland Volcano Under Alert in Alaska

The alert level for an Alaska volcano is being raised after officials say persistent thermal anomalies have been spotted in satellite data.

The Alaska Volcano Observatory on Wednesday raised the level Cleveland Volcano to advisory from unassigned.

There is no real-time seismic network at the volcano, located 939 miles southwest of Anchorage on an uninhabited island. Officials are not able to track local earthquake activity related to volcanic unrest.

Short-lived explosions with ash clouds or plumes exceeding 20,000 feet above sea level are frequent on Cleveland. It last showed signs of unrest last summer, with a small ash emission and lava flows on its upper flanks.

The observatory says the last significant eruption of the 5,676-foot volcano began in February 2001 and eventually produced a lava flow that reached the ocean.