Spectral characteristics and stress drop for microearthquakes near Fairview Peak, Nevada

Frequency and amplitude characteristics were studied for microearthquakes recorded on a local network of vertical-component seismographs in the Fairview Peak area of central Nevada. Maximum trace amplitude of the events decreased with focal distance approximately as R−1.9. Site amplification, by a factor of 2, was observed for the only station not located on rock. Comparison of observed spectra for these events with theoretical spectra given by Brune indicates stress drops ranging from 0.04 to 0.60 bar. Calculated source dimensions and seismic moments for microearthquakes in this area are in agreement with results of earlier studies. When location of the events is considered, the variation in stress drop appears to be related to differences in the faulting mechanisms.