Estimation of earthquake effects associated with large earthquakes in the New Madrid seismic zone

Abstract

Estimates have been made of the effects of a great earthquake (M = 8.6, I = XI), a large earthquake (M = 7.6, I = X), and a moderate earthquake (M =6.7, I Q = ix) hypothesized to occur anywhere in the New Madrid seismic zone. The estimates are based on the distributions of observed intensities associated with the earthquakes of 1811-12, 1843 and 1895, although the effects of other historical shocks are also considered. The resulting composite type intensity maps for each magnitude are believed to represent the upper levels of shaking likely to occur. A composite intensity map shows a more widespread distribution of effects than would result from a single earthquake of the chosen magnitude, say 8.6, because the distributions of effects were plotted for magnitude-8.6 earthquakes that could occur anywhere from the northern to the southern end of the seismic zone, and the maximum of the resulting intensities was chosen for each point on the map. Specific intensity maps have also been developed for seven cities near the epicentral region taking into account the most likely distribution of site response in each city. Intensities found for the magnitude-8.

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Report on recommended list of structures for seismic instrumentation in the New Madrid region

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