Mt. Fitzherbert

Recent Observations: A swarm of small, shallow earthquakes between Mount Shasta and Medicine Lake volcanoes has been ongoing since Thursday, 7 August. The sequence began with a M2.5 at 08:27 PDT on August 7, and included a M3.5 earthquake followed by a number of smaller earthquakes over the past 24 hours, including several M>2 earthquakes this morning (8 August). Earthquake epicenters are clustered near the trace of several NNW-trending regional faults and are located ~8 miles SE of the locus of the June-August 1978 Stevens Pass swarm, which included three M>4 earthquakes. The location and character of the 2008 earthquakes are consistent with a tectonic (non-volcanic) origin for the swarm. However, because the swarm is occurring in an area of scattered volcanic vents, we will continue to monitor the swarm closely and will issue updates if the situation warrants.