Seismic activity beneath the volcano has recently increased and is continuing, although no signs of unrest have been detected so far.
Depths of quakes were mostly deep in the beginning, about 25 km, but became rapidly shallower at a depth approx. 5 km beneath the volcano over the following four days. Since early January, earthquakes have become more intense at an average rate of ten per day. The largest event took place on 20 November with a magnitude M 4.6.
Therefore, the AVO volcano observatory raised the alert status to „yellow“.
The AVO continues: „Within the Katmai group of volcanoes, earthquakes are typically clustered in three regions: under Trident Volcano, under Mount Katmai to the east, and under Martin and Mageik volcanoes to the west. The current period of seismic unrest is most prominent in the area under Trident, but the rate of earthquakes has also increased in the region beneath Martin and Mageik volcanoes. Because of the initial sequence of deep earthquakes and continued episodes of tremor under Trident, it is most likely, though not certain, that the unrest observed in the area is due to movement of magma or magmatic fluids at depth there.“
There are no expectations of impending and sudden eruption to happen as the similar activity might occur from time to time. The AVO observatory suggests extra shallow seismic activity and other signs of unrest, such as gas emissions, elevated surface temperatures etc.
Source: Alaska Volcano Observatory volcano activity update 23 February 2023