Recent seismic zone maps show large values of maximum expected ground motion for the zone of large historic earthquakes in central Nevada, but low values along a zone of major faults in the Sierra Nevada-Great Basin boundary zone (SNGBZ). Estimates of maximum magnitude for this zone, based on a comparison of mapped faults with seismicity, range from 8.0 or greater in the area south of Bishop to 7.5 to 7.8 in the area between Bishop and Susanville. With population concentrations in the Reno-Carson City-Tahoe area, the northern SNGBZ represents the most serious seismic risk for the Nevada-eastern California region, and seismic zone maps should be changed to reflect this risk. In compiling these maps, magnitude-acceleration relationships should be used that are appropriate to source types and propagation paths in the Great Basin. Relationships between maximum acceleration and magnitude based on source-receiver paths along the California coast (i.e., Schnabel and Seed, 1973) may overestimate near-source acceleration in the Great Basin by a factor of 2 or more.

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