Probabilistic liquefaction severity index maps of the State of Utah (OFR-159)

By: M. A. Mabey and T. L. Youd

Liquefaction Severity Index maps for the state of Utah were generated using probabilistic analysis. The Liquefaction Severity Index (LSI) expresses the maximum magnitude of differential deformation which would be the result of the liquefaction of a soil. LSI is defined as the maximum displacement, in inches, occurring in Holocene flood plain deposits and is a function of distance from the causative earthquake and the magnitude of that earthquake.

Maps of LSI have been prepared for 10% probability of exceedence in four different exposure periods, 10 years, 50 years, 250 years, and 1000 years. The latter is intended to approximate a deterministic case. While the Wasatch fault is assumed to be the greatest source of earthquake shaking to cause liquefaction, these maps clearly show that a very broad area has a significant liquefaction hazard arising from the numerous other earthquake generating faults in the state. The occurrence of liquefaction requires shallow ground water, the absence of which reduces the LSI to near zero. The LSI maps quantify the probable maximum hazard due to liquefaction and can be used to reduce the risk to lifelines and other engineered structures by planning for the maximum probable effects of liquefaction.

Other Information:
Published: 1989
Pages: 28 p.
Location: Utah
Media Type: Paper Publication