We simulate surface waves in a 3-D Earth model using a spectral element method for existing kinematic source models of the M-W 8.1, 25 March 1998 Balleny Islands earthquake. The 3-D model incorporates lateral variations in the crust and mantle on the basis of models Crust2.0 and S20RTS. Our objective is to investigate the fit of the observed and simulated long-period surface waves in the hope of improving on the existing source models. We modify a body wave model determined by Henry et al. (2000) to improve the fit of long-period surface waveforms. We demonstrate that adding a smooth component of slip extending over a fault that connects the two subevents determined by Henry et al. (2000), without invoking slip on multiple fault planes or on unconnected fault patches, provides reasonable fits to long-period surface waves as well as body waves.
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