J.D. Frost | USGS Science

USGS1998

The Loma Prieta, California, earthquake of October 17, 1989: Liquefaction

The 1989 Loma Prieta earthquake both reconfirmed the vulnerability of areas in the San Francisco-Monterey Bay region to liquefaction and provided an opportunity to test methodologies for predicting liquefaction that have been developed since the mid-1970's. This vulnerability is documented in the chapter edited by O'Rourke and by the investigators in this chapter who describe case histories of liquefaction damage and warn us about the potential for even greater damage from liquefaction if an earthquake similar to the 1989 Loma Prieta earthquake, but located closer to their study sites, were to occur.

California↗

USGS1997

Spatial earthquake hazard assessment of Evansville, Indiana

The earthquake hazard has been evaluated for a 150-square-kilometer area around Evansville, Indiana. GIS-QUAKE, a system that combines liquefaction and ground motion analysis routines with site-specific geological, geotechnical, and seismological information, was used for the analysis. The hazard potential was determined by using 586 SPT borings, 27 CPT sounding, 39 shear-wave velocity profiles and synthesized acceleration records for body-wave magnitude 6.5 and 7.3 mid-continental earthquakes, occurring at distances of 50 km and 250 km, respectively. The results of the GIS-QUAKE hazard analyses for Evansville identify areas with a high hazard potential that had not previously been identified in earthquake zonation studies. The Pigeon Creek area specifically is identified as having significant potential for liquefaction-induced damage. Damage as a result of ground motion amplification is determined to be a moderate concern throughout the area. Differences in the findings of this zonation study and previous work are attributed to the size and range of the database, the hazard evaluation methodologies, and the geostatistical interpolation techniques used to estimate the hazard potential. Further, assumptions regarding the groundwater elevations made in previous studies are also considered to have had a significant effect on the results.

Indiana↗