Liquefaction Hazard near the Ohio River from Midwestern Scenario Earthquakes

Abstract

Evansville, Indiana, and Henderson, Kentucky, located on the banks of the Ohio River, are susceptible to liquefaction-induced damage in the event of significant earthquake shaking. A sequence of three earthquakes with magnitudes greater than 7 occurred near New Madrid, MO, in 1811–1812, producing ground motions with Modified Mercalli Intensity VII in the Evansville-Henderson area near the Ohio River, 180 km away from the source. In addition, liquefaction evidence has been documented less than 40 km from Evansville from two large earthquakes that occurred within the past 12,000 years in the Wabash Valley. As a complement to recent work on the probabilistic seismic hazard analysis and scenario earthquake ground motions, we have calculated the liquefaction hazard within the 33 × 42–km 2 area containing Evansville and Henderson, based on scenario earthquakes from each of these source regions. Cone penetrometer test data were used to estimate the factor of safety against liquefaction at 58 sites in the study region. Liquefaction potential index ( LPI ) maps were calculated using a probabilistic method to account for the uncertainty due to spatial variability of soil profiles. The site response and peak ground accelerations for the scenario earthquakes vary across the study area, resulting in significant variations in LPI . The LPI is highest in the outwash terraces at the edges of the Ohio River Valley for both scenario earthquakes. However, the probability of liquefaction severe enough to produce lateral spreading ( LPI > 12) was less than 20 percent in most of the study area for both scenarios.