Abstract

Crustal structure in central California (between the latitudes of 36° and 41°N) including the Sierra Nevada was studied by travel times of Pn waves from Nevada explosions and earthquakes, dispersion of surface waves, and correlation between computed and observed gravity anomalies.

Simple two-dimensional models are presented for the structure, parameters of which are determined by least-squares from Pn observations. Theoretical gravity distributions expected from the crustal models are computed by a two-dimensional technique and compared with Bouguer anomalies. In the preferred model, the overall crustal depths to the Moho-discontinuity beneath the Pacific coast region, the Central Valley and the Sierra Nevada are found to be about 22, 26 and 43 km, respectively, indicating a steep crustal thickening under the high mountain region. The dispersion of group velocities of Rayleigh and Love waves passing across the region was investigated from Nevada and Utah earthquakes; Love waves from the Utah earthquake give evidence in support of the derived structure.

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