HR: 11:35h
AN: S32A-04 INVITED     [Abstracts]
TI: Generation and Mitigation of Surface-Generated Scattered Phases in Teleseismic Imaging.
AU: * Poppeliers, C
EM: christian.poppeliers@angelo.edu
AF: Angelo State University, Dept. of Physics PO Box 10904, ASU Station, San Angelo, TX 76909 United States
AB: Many of the current algorithms that earthquake seismologists use to image the forward scattered teleseismic wavefield have been borrowed from the oil industry. Of course, modifications to the original algorithms allow earthquake seismologists to image forward scattered wavefields rather than reflected, or backscattered, wavefields. A common theme that is represented in these imaging algorithms is the single-scattering, or Born, approximation. The problem is when the data contains arrivals that do not adhere to this approximation (for example, free-surface reverberations, scattered surface waves, etc.). In a typical oil industry type seismic reflection survey, the recording geometry and the density of the geophones allow the application of techniques to "remove" the arrivals that are not considered to arise from primary reflections. Although such techniques are arguably model-based, applying them to the raw data often removed enough of the non-primary arrivals to a degree that allows the application of Born-type imaging algorithms. In teleseismic imaging, we are faced with the same problem of non-primary arrivals "contaminating" our data. Therefore if we wish to use imaging algorithms that are based on the Born Approximation, we must develop techniques to remove non-primary arrivals. In this talk, I will focus on the documentation and mitigation of surface scattered phases that are generated by high magnitude, near-surface, lateral velocity variations. Although most of the work here will be with synthetic data, the generation of surface-scattered phases in synthetic velocity models is consistent with observations of field data. However, because the algorithms presented require data that is not spatially aliased, I will discuss the effects of spatial sampling interval (i.e. station density) on the efficacy of such mitigation techniques.
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory and modeling
DE: 7294 Instruments and techniques
DE: 7203 Body wave propagation
SC: Seismology [S]
MN: 2004 AGU Fall Meeting