USGS Volcano Notice for Aviation - DOI-USGS-AVO-2023-07-18T17:18:02-08:00

There has been an increase in the number of earthquakes observed near Cleveland volcano over the past week. Numerous earthquakes have been detected and 37 of these were large enough to be located by the local seismic network. Most of the earthquakes from early in the week located in the mid to shallow portions of the Earth’s crust, less than 11 miles (18 km) below the surface, while more recent earthquakes have been located at shallower depths, less than 4 miles (6 km) below the surface. These earthquakes are small (less than magnitude 2), but the frequency of events is unusual for Cleveland. These data along with satellite observations of elevated surface temperatures at the summit crater and continued gas emissions suggest an increased likelihood of a future eruption. In response, the Alaska Volcano Observatory is increasing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY.

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.

Cleveland volcano is currently monitored with a five-station real-time seismic network. Based on past events, explosive eruptions of Cleveland may occur with little or no warning. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.