Stochastic Variation of Earthquake Ground Motion in Space and Time

Abstract

Consideration of the spatial as well as temporal variation of earthquake ground motions may be important in the design of structures with spatially extended foundations and lifeline systems. In this paper, the ground motion during a specific earthquake event is conceived as the realization of a space‐time random field. Following a brief review of pertinent results from the second‐order theory of random fields and a description of spectral estimators, accelerograms recorded by the SMART 1 seismograph array in Lotung, Taiwan, are examined to determine the frequency‐dependent spatial correlation of earthquake ground motions. A scheme for processing seismograph array data is proposed, and similarities and differences in the motions recorded during different events are noted. Finally, key parameters characterizing the correlation structures are identified and a preliminary mathematical model is suggested for the space‐time correlations.