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Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/1941

Authors: Bernard, P.*
Herrero, A.*
Title: Slip heterogeneity, body-wave spectra, and directivity of earthquake ruptures
Issue Date: Dec-1994
Series/Report no.: 37/6
URI: http://hdl.handle.net/2122/1941
Keywords: fault slip
seismic rupture
slip heterogeneity
directivity effect
kinematic rupture
stochastic model
Abstract: We present a broadband kinematic model based on a self-similar k-square distribution of the coseismic slip, with an instantaneous rise-time and a constant rupture velocity. The phase of the slip spectrum at high wave number is random. This model generates an ?-squared body-wave radiation, and a particular directivity factor C2d scaling the amplitude of the body-wave spectra, where Cd is the standard directivity factor. Considering the source models with a propagating pulse and a finite rise-time, we assume that within the slipping band, the rupture has some random character, with small scale rupture in various directions. With such a model, the pulse cannot be resolved, and the directivity factor is still C2d at low frequency; at periods shorter than the rise-time, however, the directivity effect drops to much smaller rms values. This frequency dependent directivity effect, which is expected to be the strongest for sites located in the direction of rupture, was evidenced for the Landers 1992 earthquake, leading to a 2 to 3 s rise-time of the slip pulse. This kinematic model can be used with more refined theoretical Green's functions, including near-field terms and surface waves, or with empirical Green's functions, for generating realistic broadband records in the vicinity of moderate to large earthquakes, in a frequency range relevant for engineering applications (0 Hz to about 20 Hz).
Appears in Collections:04.06.99. General or miscellaneous
Annals of Geophysics
Papers Published / Papers in press

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