L. M. Dorman, A. W. Sauter and others, Observations and causes of seismic background noise in the nearshore region. Unpublished

The spectral density of ocean waves (swell) measured by an array of Ocean-Bottom Seismometers at a depth of 30 meters offshore of Southern California, more specifically off Marine Corps Base Camp Pendleton.  At the center of the plane defined by the red and green vectors, the horizontal slowness is zero (infinite velocity) and the maximum values are 200 seconds per kilometer.  Up (opposite the blue axis) is increasing period, with the greatest value being 16 seconds.  The strongest component is in the ENE direction with a subsidiary peak in a more northerly direction.  </COMMENT>