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Effects of Fault Dip and Slip Rake on Near-Source Ground Motions: Why Chi-Chi Was a Relatively Mild M 7.6 Earthquake

Aagaard, Brad T. and Hall, John F. and Heaton, Thomas H. (2002) Effects of Fault Dip and Slip Rake on Near-Source Ground Motions: Why Chi-Chi Was a Relatively Mild M 7.6 Earthquake. PEER Report, 2002/12. . (Unpublished)

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This study focuses on how the fault dip and slip rake angles affect near-source ground motions as faulting transitions from strike-slip motion on a vertical fault to thrust motion on a shallow dipping fault. Ground motions are computed for five fault geometries with different combinations of fault dip and rake angles, and common values for the fault area and the average slip. With the fault reaching the surface in each scenario, the ground motions are dominated by Love and/or Rayleigh waves. The strike-slip faulting tends to generate Love waves, whereas the thrust faulting tends to generate Rayleigh waves. The degree to which the rupture reinforces these waves affects the severity of the shaking. For strike-slip faulting this directivity effect is most pronounced for unilateral rupture, while for thrust faulting it is most pronounced for up-dip rupture. These simulations suggest that the long-period ground motions in the 1999 Chi-Chi earthquake in Taiwan were not as severe as would be expected for other events of the same size with different styles of faulting or a deeper hypocenter.

Item Type:Report or Paper (Technical Report)
Related URLs:
URLURL TypeDescription ItemJournal Article
Hall, John F.0000-0002-7863-5060
Heaton, Thomas H.0000-0003-3363-2197
Additional Information:PEER Report 2002/12. Access to the Hewlett-Packard V-Class computer, located at the California Institute of Technology, was provided by the Center for Advanced Computing Research. This work was supported in part by the Pacific Earthquake Engineering Research Center through the Earthquake Engineering Research Centers Program of the National Science Foundation under award number EEC-9701568.
Group:Seismological Laboratory
Funding AgencyGrant Number
Series Name:PEER Report
Issue or Number:2002/12
Record Number:CaltechAUTHORS:20200518-124916954
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103279
Deposited By: Tony Diaz
Deposited On:18 May 2020 19:57
Last Modified:18 Aug 2020 21:04

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