Ground Strain Estimation for Seismic Risk Analysis

Abstract

Under the assumption that strong motion earthquakes result primarily from surface waves in a layered medium resting on a semi‐infinite rock formation, a method is developed to derive the expression for the Rayleigh wave that produces acceleration at the ground surface with a specified power spectral density. The Rayleigh wave characteristics are then used to obtain a corresponding free‐field normal ground strain at any depth in the medium. Other important features of this paper are as follows: (1) The ground acceleration and strain are both modeled as Gaussian stationary processes; (2) the power spectral densities used for these processes are functions of the earthquake's magnitude, epicentral distance (reflecting the attenuation effect), and the