Joint 70th Rocky Mountain Annual Section / 114th Cordilleran Annual Section Meeting - 2018

Paper No. 71-1
Presentation Time: 8:30 AM-4:30 PM


BRUMBAUGH, David S., School of Earth Sci. & Env. Sust, Northern Arizona University, PO Box 4099, Flagstaff, AZ 86011

An earthquake swarm occurred during April and May, 2016, in the area west of the Grand Wash fault in northwest Arizona. A total of 62 events ranging from MD 0.4 to ML 3.8 were located. The range in magnitudes and location of the swarm in an area with a historically low frequency of events presents an opportunity to better understand the physical characteristics of the Grand Wash area. Preliminary analysis of the seismic data was conducted with application of the Wadati Ratio, Poissons Ratio, and the b-value obtained from the slope of the FMD plot. Both the Wadati Ratio and the Poissons Ratio values from the swarm data are close to the average worldwide values for shallow crust (1.73, 0.24). The b-value of 0.62 falls within the range of most worldwide values calculated in other studies, but somewhat below that for swarms in continental extensional terranes. Further analysis of the Grand Wash swarm will build upon these preliminary results and focus on a comparison of the same three parameters in this study to those obtained regionally from studies on the Southern Colorado Plateau and the Southern Basin and Range and Transition Zone provinces.