The Pg-Pn method of determining depth of focus with applications to Nevada earthquakes

The Pg-Pn method is theoretically developed, including a complete error analysis, and then applied to some Nevada earthquakes. It is found that, as expected, the method is very sensitive to the crustal model used, and the appearance of large errors in depths of focus calculated for some earthquakes leads to the conclusion of a major discontinuity in crustal thickness (ca. 10 km) north and east of Walker Lake, Nevada. This discontinuity may have its surface expression in the Walker Lane, a major right-lateral shear zone which has been defined on both physiographic and geologic grounds.