Description: McGimsey and others (2004) report on an earthquake swarm detected May 11, 2001, at Okmok Volcano: "At 8:00 ADT (16:00 UTC) on the morning of May 11, 2001, AVO seismologists detected on the Makushin seismic network a swarm of earthquakes occurring under Okmok volcano prompting AVO to release an Update at 17:00 ADT (01:00 UTC). The events were ML=2.0-3.6 - too small to be felt by nearby residents - and determined to be possibly of volcanic origin. Satellite observations revealed no volcanic activity nor thermal anomalies. On-going satellite-based deformation measurements (SAR interferometry) show that the center of the caldera has inflated 20 cm between the 1997 eruption and September 2000. In April, 2001, AVO scientists observed an area of snowmelt in the caldera; although possibly indicative of heat flux, the area corresponded to the thickest part of the 1997 lava flow, which may still be hot (Patrick and others, 2003). By May 15, 2001, the earthquake swarm had greatly diminished. Okmok was last mentioned in the May 25, 2001 AVO Weekly Update."