Collaborative Research: Correlogram Migration of Scattered Teleseismic Body Waves

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A new methodology for the imaging of the earth's reflectivity distribution by correlogram migration of scattered teleseismic body waves is being investigated. The correlation migration methods developed for applications in seismic exploration are being extended to the imaging of crustal and upper mantle structure beneath a dense receiver array using teleseismic body waves. These waves include P to SV and P to P surface reflected phases, in addition to other direct and surface scattered phases. The result is an image of the reflectivity distribution beneath the recording array for each of the scattered waves. The current imaging methods using receiver functions for laterally varying structure mostly use directly converted P to SV arrivals for subsurface illumination. Correlation imaging of ghost reflections provides complementary resolution to that of P to SV transmitted waves. Questions concerning the practicality of using correlogram migration of different phases for the imaging of laterally varying media using teleseismic array data are being addressed. Also, the limitations of correlogram migration as a function of data quality, receiver spacing and type of teleseismic data used are being investigated. Since for practical teleseismic array configurations, some aliasing effects will result, a new beam-like migration algorithm, call wavepath migration, which is less sensitive to these effects, is being tested for the imaging of teleseismic array data. The correlogram migration of teleseismic data is being tested using different teleseismic array configurations across the Wasatch Front. The significance of this research is the development of new imaging methods for laterally varying structure using teleseismic data, which generalizes receiver function imaging to include converted as well as ghost reflections. Correlogram imaging is most effective for dense seismic networks.