Simulation of Ground Motion Using the Stochastic Method

Abstract

-A simple and powerful method for simulating ground motions is to combine parametric or functional descriptions of the ground motion's amplitude spectrum with a random phase spectrum modified such that the motion is distributed over a duration related to the earthquake magnitude and to the distance from the source. This method of simulating ground motions often goes by the name ''the stochastic method.'' It is particularly useful for simulating the higher-frequency ground motions of most interest to engineers (generally, f > 0:1 Hz), and it is widely used to predict ground motions for regions of the world in which recordings of motion from potentially damaging earthquakes are not available. This simple method has been successful in matching a variety of ground-motion measures for earthquakes with seismic moments spanning more than 12 orders of magnitude and in diverse tectonic environments. One of the essential characteristics of the method is that it distills what is known about the various factors affecting ground motions (source, path, and site) into simple functional forms. This provides a means by which the results of the rigorous studies reported in other papers in this volume can be incorporated into practical predictions of ground motion.

Estimation of Nonlinear Soil Behavior During the 1999 Chi-Chi, Taiwan, Earthquake

“…Since the purpose of our study is to simulate soil behavior, we tried to simulate most accurately motion at the ''input'' of the soil layers. In the calculations, we used Boore's stochastic approach (BOORE, 2003); however, we modified his method to account for the dimensions of the source and slip distribution over the fault plane.…”

“…The spatial orientation and dimensions of the fault plane, the coordinates and depth of the hypocenter, the slip velocity and slip distribution over the fault plane were derived from the paper by CHI et al (2001). Frequency-dependent attenuation effects of the propagation path are modeled through the function Q(f) as described in BOORE (2003). We assumed the relationship estimated for the Taiwan area from coda-waves by CHEN et al (1989): Q(f) = 117f 0.77 .…”

“…We assumed the relationship estimated for the Taiwan area from coda-waves by CHEN et al (1989): Q(f) = 117f 0.77 . Kappa operator was used for additional attenuation of the spectra (ANDERSON and HOUGH, 1984;BOORE, 2003); we took j = 0.07 sec. Thus, these parameters were taken as the same as those used in the work by ROUMELIOTI and BERESNEV (2003), because our calculations show that these values well fit the observed data and only slightly define the simulations (i.e., their variations within some limits do not greatly influence the obtained accelerograms).…”

Simulation of Strong Ground Motion During the 1950 Great Assam Earthquake

“…The fault geometry is same as that reported by BEN-MENAHEM et al (1974). The finite fault seismological model is implemented in the time domain through computer simulation, consisting of the following three steps (BOORE, 1983(BOORE, , 2003. Acceleration time histories of length equal to the strong motion duration (BOORE and ATKINSON, 1987),…”

Broadband Ground-Motion Simulation Using Energy-Constrained Rise-Time Scaling

“…Several different methods have been developed in the past to meet this challenge. Stochastic methods, such as used by Boore (2003) and Motazedian and Atkinson (2005), perform well at predicting amplitude and frequency content at large distances over a wide frequency range. However, they do not provide correct phase information or good representation of near-fault ground motion in the time domain.…”