PALEOLIQUEFACTION STUDIES IN CONTINENTAL SETTINGS

Abstract

Research of the past 15 years has reported the manifestations of seismically induced liquefaction that occur in the sedimentary conditions commonly found in continental settings. And, criteria have been developed and published that can demonstrate a seismic origin for features of liquefaction origin. We present guidelines for conducting a paleoliquefaction search by means of geologic and geotechnical parameters. We also address the interpretation of results of a paleoliquefaction study in terms of locating the source region of a paleo-earthquake and back-calculating its strength of shaking and magnitude. Our critique of the geotechnical methods for these back-calculations points out uncertainties in the techniques that are most commonly used. The guidelines that we present for a paleoliquefaction search are in terms of both geologic and geotechnical parameters because it is the combination that is critical. Neither suffices alone, and the relations between the geologic setting and geotechnical properties must be appreciated in order to understand why seismically induced liquefaction features are to be found in some locales and not in others.