An increasing number of earthquakes have been monitored in the vicinity of the volcano over the past week.
Thirty-seven quakes were strong enough to be located by the local seismic instrument, although mostly with a magnitude less than M 2, but rarely more frequently than usual. In the early week, most of earthquakes were detected at 11 km depth but become shallower at less than 6 km beneath the surface as indicated by seismic recordings.
In addition, elevated surface temperatures and continuing gas emissions suggest an increased likelihood of eruption in the near future.
In response, the AVO observatory raised the alert status for the volcano to „Yellow“.
The local observatory continues: „The last eruptive activity at Cleveland volcano was a short-lived explosion during the evening (local time) of June 1, 2020. Despite the current pause, the eruptive period at Cleveland, dating back to 2001, remains ongoing and future explosions are likely. These have occurred without warning and typically generate small clouds of volcanic ash that are a hazard in the immediate vicinity of the volcano, though more significant ash emissions are possible.“
Source: Alaska Volcano Observatory volcano activity update 20 July 2023