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Robert Phinney - About Me

Southern Sierra Receiver Functions

Ruppert & Fliedner, Sierra refraction experiment

Portable seismic arrays used with earthquake and explosion sources for detailed imaging of the crust can now be applied to the study of structure in the upper mantle, extending the techniques used in reflection profiling. My major research interest is in applying and extending these techniques in different regions of the United States. The major geophysical distinctions between these regions, in respect to gravity, topography, crustal thickness, and Cenozoic tectonic history, for example, must be reflections of significant differences in the structure and physical properties of the underlying mantle. Most of the energy in earthquake signals is in the coda, consisting of phases scattered by layers and heterogeneities. Extraction of these signals requires small arrays and computational techniques for signal detection. In the Southern Sierra Continental Dynamics Project, small arrays of 3-component instruments will be used to detect and identify scattered P and S signals produced by the Moho and by other discontinuities in the upper mantle, using both teleseisms and regional earthquakes. This experiment is aimed at establishing the nature of the root under the Sierra Nevada and in trying to understand the driving forces for the rapid Pleistocene uplift. In addition, a series of long-line deployments (in collaboration with other universities) of portable instruments is planned for the northeast United States to permit detailed imaging of lateral variations of upper mantle structure.