Abstract
AbstractGenerating broadband ground motions requires fine enough scales in the source model, but small scales may lead to unacceptable computational efforts for source inversion. To resolve this challenge, a novel kinematic source inversion method is proposed in this study to map the detailed rupture process associated with broadband seismic radiation. This method addresses two key issues for imaging the rupture process of earthquakes: proper source models describing the rupture process and accurate Green’s functions. For the first issue, the rupture process of target earthquakes is modeled by a recently proposed multidimension source model, which is composed of several superimposed layers with degressive scales to generate broadband ground motions. Due to the self‐similarity of the parameters of subsource on different layers, the number of variables to be considered in the inversion procedure is comparable to that of the conventional finite‐fault source model. For the second issue, the spectral element method is used to compute the Green’s functions with high‐resolution topography and three‐dimensional (3D) velocity structures. The introduction of accurate 3D velocity structures enables to reproduce the ground motions of target earthquakes in a wide range of frequency. With the multidimension source model and accurate Green’s functions, an evolutionary many‐objective optimization algorithm is used to search for the best rupture‐process parameters. The rupture process of the 1992 Landers earthquake is mapped by the proposed inversion method, and the ground motions from the forward simulation with the inverted rupture process have an impressive agreement with the records in a wide range of frequency.
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