Abstract:
The accurate modeling of ground motion for induced-seismicity hazard
estimation is critically dependent on how amplitudes scale with distance near the hypocenter.
A rich database of ground motions from small events recorded at close distances
in the Geysers region of California has been used to constrain the near-distance
saturation effects that control the maximum observed ground motions and intensities
for shallow-induced events. The results of this study support the modeling of these
effects using an equivalent point-source concept, in which the effective source depth
increases from a value near 1 km at moment magnitude (M) of 2 to a value near 3 km
at M 4. This near-distance saturation behavior can be applied to the development of
ground-motion models for induced seismicity in any region.
