A year of microseisms in southern California
Article first published online: 17 OCT 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 20, October 2007
How to Cite
2007), A year of microseisms in southern California, Geophys. Res. Lett., 34, L20304, doi:10.1029/2007GL031091., and (
- Issue published online: 17 OCT 2007
- Article first published online: 17 OCT 2007
- Manuscript Accepted: 30 AUG 2007
- Manuscript Revised: 29 AUG 2007
- Manuscript Received: 22 JUN 2007
 Microseisms are due to continuous harmonic forcing by ocean waves, whose sources vary in time, frequency, and azimuth. Using frequency-domain array beamforming, this variation is studied using one-year of continuous seismic data from 155 stations in southern California. Detailed analysis of data delineates spatiotemporal variations of sources for the primary and secondary microseisms. Both types of microseisms are generated near the coasts but the locations of excitation are different and change with season. Often sources are multiply located but can be spread out over wider areas, especially in the case of secondary microseisms. Distant storms can also be seen occasionally in the frequency range between the primary and secondary microseisms where spectral amplitudes from nearby sources are low.