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USGS1988

Parkfield, California, liquefaction prediction (USA)

The primary purpose of this short note is to formally record the liquefaction prediction (Holzer et al., 1986) made in connection with this predicted earthquake. In addition, this note serves to alert the seismic engineering community to special instrumentation being installed at the prediction site. The instrumentation will consist of 4 downhole accelerometers at depths ranging from 3-30 m, a surface accelerometer, 7 dynamic piezometers distributed in the sand strata between depths of 5 and 15 m, and a network of bench marks for measuring permanent ground deformation.

Califonia↗

USGS1982

Application of modulus degradation model of clays

A degradation model is applied in conjunction with different soil models and stress-strain relations to site response analyses during earthquakes. To evaluate the effects of degradation, computations on two clay deposits subjected to both high and low-level input excitations are conducted. In addition, modulus degradation with or without shear strength reduction is discussed. In terms of surface response, degradation has little effect in the case of low-level excitation. With high-level excitatfons, however, degradation causes lower surface spectral response in the shorter period range, and the difference is on the same order as that from different soil models. Where surface response differs, the use of degradation with strength reduction is less conservative when compared to the use of degradation without strength reduction.

Journal of the Geotechnical Engineering Division, ↗