Data are available at this site from three ULF-EM sites maintained by Stanford University in co-operation with the U.S.G.S. and with assistance from U.C. Berkeley:

JRSC Jasper Ridge Biological Preserve, Stanford University
MHDL Marin Headlands, Golden Gate National Recreation Area
BRIB Russell Reservation, Briones Reserve, U.C. Berkeley
and from two stations maintainted by UC Berkeley with assistance from the U.S.G.S. and Stanford University:
SAO San Andreas Geophysical Observatory, Hollister
PKD Bear Valley Ranch, Parkfield

Station metadata can be found at the Berkeley Digital Seismic Network (BDSN) and Northern California Earthquake Data Center (NCEDC) sites ( including a brief listing of station location and operation dates and a description of each available channel.