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Path durations for use in the stochastic‐method simulation of ground motions

August 1, 2014

The stochastic method of ground‐motion simulation assumes that the energy in a target spectrum is spread over a duration DT. DT is generally decomposed into the duration due to source effects (DS) and to path effects (DP). For the most commonly used source, seismological theory directly relates DS to the source corner frequency, accounting for the magnitude scaling of DT. In contrast, DP is related to propagation effects that are more difficult to represent by analytic equations based on the physics of the process. We are primarily motivated to revisit DT because the function currently employed by many implementations of the stochastic method for active tectonic regions underpredicts observed durations, leading to an overprediction of ground motions for a given target spectrum. Further, there is some inconsistency in the literature regarding which empirical duration corresponds to DT. Thus, we begin by clarifying the relationship between empirical durations and DT as used in the first author’s implementation of the stochastic method, and then we develop a new DP relationship. The new DP function gives significantly longer durations than in the previous DP function, but the relative contribution of DP to DT still diminishes with increasing magnitude. Thus, this correction is more important for small events or subfaults of larger events modeled with the stochastic finite‐fault method.

Publication Year 2014
Title Path durations for use in the stochastic‐method simulation of ground motions
DOI 10.1785/0120140058
Authors David M. Boore, Eric M. Thompson
Publication Type Article
Publication Subtype Journal Article
Series Title Bulletin of the Seismological Society of America
Index ID 70108033
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center