Seismic Hazard Study for Utah.
Environmental research papers,
AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA
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With the use of two distinct seismic regionalizations, seismic hazard evaluations were conducted for Utah. The two regionalizations were used to depict the possible extremes in further seismic activity in the Utah area. The primary distinction in the models was the treatment of Basin and Range seismicity. In one model, the seismic activity in this province was uniformly distributed in the other it was concentrated at the province boundaries. With these models, contour maps of peak acceleration and velocity were constructed for Utah, and annual risk curves were evaluated for specific sites within the state. In addition, deterministic hazard estimates were made based on known and suspected Quaternary faults in Utah. It was concluded that for near-term hazard evaluations, the subplate margin provided the most useful hazard projection. Based on this model, 90 percent confidence-level acceleration in Utah are less than 115 cmsec for any 10-year period and less than 270 cmsec for any 50-year period. The deterministic modeling predicts that accelerations over 0.8 g are possible throughout much of western Utah and, in particular, the proposed MX basing area. However, it is likely that accelerations of this magnitude would occur on the order of less than once in several thousand years at any specific site within the state. Author