Apparently dormant and not so dormant volcanoes in Southern California and Nevada are showing seismic activity in the last few days according to Dutchsinse:
Pisgah, Mammoth in California and Twin Buttes, Nevada…
http://volcanoes.usgs.gov/volcanoes/lavic_lake/
This is a useful WORLD WIDE SEISMIC MONITOR LINK :
http://ds.iris.edu/seismon/bigmap/index.phtml