Figure 1. Location of earthquakes (circles) and some of the broadband seismic stations (triangles) used in this study. We also show the hypocenter location (stars) of historical earthquakes and the approximate location of surface rupture (gray lines) which occurred in eastern California and central Nevada since 1860 (see Table 1 for references).

Figure 2. P- and S-wave velocity profiles for the four 1-D models used in the moment tensor inversions. The models include the WUS-western United States model [Ritsema and Lay, 1995], BR1- Basin and Range model 1 [Bhattacharyya et al., 1999], SC-Southern California model [Dreger and Helmberger, 1990], and GIL-Gilroy 7 model [Dreger and Romanowicz, 1994]. The models are compared to the Priestly and Brune [1978] Basin and Range velocity model estimated from surface waves.

Figure 3. Waveform fits for moment tensor inversion of (A) 1998 Lake Tahoe, (B) 1997 Fish Lake Valley, (C) 1999 Scotty's Junction, and (D) 2000 Truckee earthquakes. The solid lines are the displacement data and the dashed lines are the synthetics. Both are in microns and filtered using the same passband. All the seismograms are aligned with the origin time (see Table 2. for event numbers and source parameters).

Figure 4. Deviatoric moment tensor solutions (5 degree of freedom) and nodal planes from the major double couple of the deviatoric moment tensor. The moment tensors from areas with dense earthquake activity within the boxes are shown in separate figures: DSF-Double Spring Flat, Nevada, EV-Eureka Valley, California, FLV-Fish Lake Valley, Nevada, SJ-Scotty's Junction, Nevada, ML-Mammoth Lakes, California, COSO-Coso Geothermal Field, California, and RC-Ridgecrest, California. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 5. Moment Tensors solutions for the DSF-Double Spring Flat area. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 6. Moment Tensors solutions for the EV-Eureka Valley and adjacent areas. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 7. Moment Tensors solutions for the FLV-Fish Lake Valley area. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 8. Moment Tensors solutions for the SJ-Scotty's Junction area. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 9. Moment Tensors solutions for the ML-Mammoth Lakes, Long Valley Caldera, and adjacent areas. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 10. Moment Tensors solutions for the COSO-Coso Geothermal Field and RC-Ridgecrest areas. The event numbers from Table 2 are labeled above the focal mechanisms.

Figure 11. Map of P-axes (gray arrows) and T-axes (black arrows) from the major double couple of the deviatoric moment tensor solutions. The arrows point in the direction of the P- or T-axis trend and the arrow lengths and sizes are proportional to the plunge angle (see scale). The approximate boundaries between the Sierra Nevada (Region 1), Walker Lane (Region 2), and Basin and Range (Region 3) are sketched and used to separate the T-axis orientations. The trend of T-axes are shown in rose diagrams and more details on their orientations are listed in Table 3.

Figure 12. Distribution of hypocenter depths estimated by seismic networks and centroid depths estimated from moment tensor inversion. For the comparison between depth estimated from seismic network and this study, we only used only 13 "a" quality events.

Figure 13. Percent double couple from deviatoric moment tensors as a function of moment magnitude. Smaller earthquakes appear to have a wider range of CLVD component most likely due to noisy data. There are also larger sized earthquakes which may have a CLVD components as high as 15% due to path propagation and site effects from unmodeled earth structure and even higher CLVD components for double events.

Figure 14. Ten Harvard (HRVD) centriod moment tensors (CMT) compared to regional moment tensor inversions (RMTI). The event dates and numbers listed above the focal mechanisms can be referenced to Table 2. Details on the comparisons are shown in Table 4.

Figure 15. P-wave first motion focal mechanisms are compared to regional moment tensors (major double couple of deviatoric moment tensor). The event dates, origin times, and numbers labeled above each focal mechanism are referenced to Table 2. Details on the comparisons are shown Table 4.

Figure 16. Nodal planes and P- and T-axis trend and plunge estimates from multiple deviatoric moment tensor inversion of Jackknife resampled datasets. The distribution, mean and standard deviation of P- and T-axis trend and plunge estimates are listed in Table 5.

Figure 17. Event 114 (Truckee) average P- and T-axis plunge and trend orientations from the deviatoric moment tensor versus decreasing number of stations used in the inversion (right to left). The average is calculated from a Jackknife resampled dataset generated when j number of stations are removed (see text for details). The error bars indicate ±1 standard deviation. The solid line is the trend or plunge estimated using all N stations.

Figure 18. Same as Figure 17 but for event 145 (Little Skull).

Figure 19. Waveforms from a foreshock, mainshock, and three aftershocks of the 1995 Border Town earthquake (Event 34 from Table 2) were modeled at Washoe City, Nevada (WCN). All seismograms are aligned with the origin time. The data and synthetics are in microns and lowpass filtered at 1 Hz. We used the focal mechanism from event 34 in Table 2. to compute the synthetics for the foreshock and aftershocks at WCN.

Figure 20. Waveforms from a mainshock, foreshock, and two aftershocks of the 1998 Incline Village earthquake (Event 87 from Table 2.) modeled at Pahrah Range, NV (PAH), Bekwourth, CA (BEK), and Washoe City, NV (WCN). All seismograms are aligned with the origin time. The data and synthetics are in microns and lowpass filtered at 1 Hz. We used the focal mechanism from event 87 to compute the synthetics for the mainshock at the three stations. The foreshock and aftershocks focal mechanisms and moment magnitudes were estimated from WCN seismograms by using a simple grid search scheme.