Ground-motion parameters of the southwestern Indiana earthquake of 18 June 2002 and the disparity between the observed and predicted values

R. Street; J. Wiegand; E.W. Woolery; P. Hart

doi:10.1785/gssrl.76.4.512

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Ground-motion parameters of the southwestern Indiana earthquake of 18 June 2002 and the disparity between the observed and predicted values

R. Street·J. Wiegand·E.W. Woolery·P. Hart

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Abstract

The M 4.5 southwestern Indiana earthquake of 18 June 2002 triggered 46 blast monitors in Indiana, Illinois, and Kentucky. The resulting flee-field particle velocity records, along with similar data from previous earthquakes in the study area, provide a clear standard for judging the reliability of current maps for predicting ground motions greater than 2 Hz in southwestern Indiana and southeastern Illinois. Peak horizontal accelerations and velocities, and 5% damped pseudo-accelerations for the earthquake, generally exceeded ground motions predicted for the top of the bedrock by factors of 2 or more, even after soil amplifications were taken into consideration. It is suggested, but not proven, that the low shear-wave velocity and weathered bedrock in the area are also amplifying the higher-frequency ground motions that have been repeatedly recorded by the blast monitors in the study area. It is also shown that there is a good correlation between the peak ground motions and 5% pseudo-accelerations recorded for the event, and the Modified Mercalli intensities interpreted for the event by the U.S. Geological Survey.

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Source-reported bounding extent: 36.756490329505176° to 39.605688178320804° latitude; -89.033203125° to -85.80322265625° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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R. Street, J. Wiegand, E.W. Woolery, P. Hart. 2005. Ground-motion parameters of the southwestern Indiana earthquake of 18 June 2002 and the disparity between the observed and predicted values. https://doi.org/10.1785/gssrl.76.4.512

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