HR: 10:20h
AN: S12B-01    [Abstracts]
TI: The use of ocean microseisms for monitoring time-dependent stress-induced crustal properties changes
AU: * Kedar, S
EM: Sharon.Kedar@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Webb, F H
EM: Frank.H.Webb@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Rodriguez, E
EM: Ernesto.Rodriguez@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Clayton, R W
EM: clay@gps.caltech.edu
AF: California Institute of Technology Seismological Laboratory, 1200 E. California Blvd., MS 252-21, Pasadena, CA 91125 United States
AU: Tanimoto, T
EM: toshiro@geol.ucsb.edu
AF: University of California, Santa Barbara Institute for Crustal Studies,, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AB: Microseisms are a neglected but rich source of continuous energy observed by the worldwide seismic network of broadband seismometers. They are generated by ocean wave action and are potential energy sources for global 4D tomography of the upper 20km of the crust where earthquakes nucleate. 4D tomography can detect small velocity changes in rocks caused by fluid migration in oil fields. This level of change is on the same order as that expected due to tectonic stress build-up and fluid migration in the crust. The inversion of seismic energy observations for stress change in the crust is dependent on sufficient knowledge of the seismic source locations and timings. Ocean microseisms could be suitable sources for 4D tomography. However, their usefulness for this application is limited by a lack of sufficient source function characterization and a thorough understanding of the temporal and spatial characteristics of the ocean wave sources. Space-based observations may be able to provide critical constraints on the non-linear wave-wave interactions at the ocean surface which generate ocean microseisms. These wave-wave interactions cause pressure pulses that are un-attenuated with depth and generate Rayleigh waves at the seafloor. The seismic record reveals a continuous ocean-generated signal, which is correlated with swell direction, magnitude, and period. If the microseismic energy sources could be properly characterized for crustal tomography, they could enable the monitoring of stress-induced crustal property changes, providing fundamental insights into the nature of stress accumulation and release in tectonically active regions.
DE: 7223 Seismic hazard assessment and prediction
DE: 8040 Remote sensing
DE: 8164 Stresses--crust and lithosphere
DE: 7200 SEISMOLOGY
DE: 4500 OCEANOGRAPHY: PHYSICAL
SC: Seismology [S]
MN: 2004 AGU Fall Meeting