HR: 17:45h
AN: S34A-08    [Abstracts]
TI: Mapping southern Californian crust with high and low frequency seismics: A comparison between tomography, receiver functions, and reflection imageries
AU: * Zhou, H
EM: h.zhou@ttu.edu
AF: Texas Tech University, Dept of Geosciences, Lubbock, TX 79409-1053, United States
AU: * Zhou, H
EM: h.zhou@ttu.edu
AF: China University of Geosciences, TESIC, 388 Lumo Road, Wuhan, 430074, China
AB: While it is not surprising that the Earth may yield different geophysical imageries at different frequency scales, how much similarity or difference is there between crustal and mantle heterogeneities of different spatial scales? What are the geologic and geodynamic implications? Of course, we have to weed out insufficiencies in data S/N ratio, data coverage, and processing methods. This study intends to provide a careful comparison between seismic imaging methods of different spatial scales in southern California where data is of the state-or-the-art quality due to the dense distribution of earthquakes and seismologic stations, as well as the use of both passive earthquake data and active Los Angeles Regional Seismic Experiment (LARSE) data. The methods include traveltime tomography of long-wavelength velocity variations, receiver functions of long-wavelength seismic discontinuities, and reflection imaging of seismic impedance contrasts or scatters using envelop stacking in comparison with prestack depth migration. The comparison indicates a broad level of similarity between seismic imageries of different wavelengths, while well-known and somewhat less-known artifacts are still a key factor to reckon with. Compared to previously published analyses of LARSE data, the prestack depth migration method can better treat lateral velocity variations in the shallow crust. Prestack depth migration also improves the resolution of reflection events in comparison with the receiver functions. Prestack depth imaging is superior than simple CMP stack techniques to process 2D seismic data in the presence of high noise level, strong lateral velocity heterogeneity and crooked survey geometry. The long-wavelength undulation of velocity contours as provided by a new deformable-layer tomography is very helpful to interpreting the reflection images. The innovative seismic imaging techniques from this study are directly applicable to EarthScope/USArray and other projects studying the structure of the crust and mantle.
DE: 0935 Seismic methods (3025, 7294)
DE: 3260 Inverse theory
DE: 6982 Tomography and imaging (7270, 8180)
DE: 7205 Continental crust (1219)
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: 2007 Fall Meeting