The Alaska Volcano Observatory said Sunday satellite data is indicating a "thermal anomaly" at Cleveland Volcano in the Aleutian Islands, which means a lava dome at the mountain may be growing.
No ash emissions have been seen since the volcano 940 miles southwest of Anchorage began its current "eruptive episode" in mid-July.
The observatory says the current episode of dome growth resumed around Sept. 3.
A growing lava dome in the crater increases the chance of an explosive eruption but does not mean one will occur.
The Alaska Volcano Observatory is a partnership between the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.