HR: 08:35h
AN: S11C-03 INVITED     [Abstracts]
TI: Locating Ocean Microseism Sources With Seismic Directional Information
AU: * Schulte-Pelkum, V
EM: vera.schulte-pelkum@colorado.edu
AF: CIRES, University of Colorado at Boulder, 2200 Colorado Ave, UCB 399, Boulder, CO 80309 United States
AU: Earle, P S
EM: pearle@usgs.gov
AF: US Geologial Survey, DFC, Box 25046, MS 966, Denver, CO 80225 United States
AU: Vernon, F L
EM: vernon@epicenter.ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr A-0225, La Jolla, CA 92093 United States
AB: We present two different methods to calculate the source azimuth of ocean generated microseismic noise on land, one from beamforming using the vertical components of a seismic array, the second from particle motion analysis at single three-component stations. We confirm our location capabilities by comparison of the microseism propagation direction with ocean wave height maps. Coupling from ocean wave to seismic energy occurs when swells hit coastlines, but it is modulated by coastal geometry. Ocean microseism generated by Atlantic storms are registered at arrays in Wyoming and southern California; such transcontinental noise events occur several times every year with a duration of 1-2 days each. We have processed continous noise registered from 1997-2004 at the ANZA array in California and investigate the influence of El Nino-Southern Oscillation events on noise levels and directions on land. We also present a real-time automated system that generates maps of noise directions from continuous seismic records. A better understanding and location of microseism sources are the first steps to a possible future use of the ocean-generated continuous noise as a signal for seismic investigations of shallow earth structure.
DE: 7255 Surface waves and free oscillations
DE: 7205 Continental crust (1242)
DE: 4203 Analytical modeling
DE: 4522 El Ni¤o
DE: 3025 Marine seismics (0935)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting