Spectral element analysis on the characteristics of seismic wave propagation triggered by Wenchuan M s8.0 earthquake

Abstract

The 2008 Wenchuan earthquake occurred in an active earthquake zone, i.e., Longmenshan tectonic zone. Seismic waves triggered by this earthquake can be used to explore the characteristics of the fault rupture process and the hierarchical structure of the Earth's interior. We employ spectral element method incorporated with large-scale parallel computing technology, to investigate the characteristics of seismic wave propagation excited by Wenchuan earthquake. We calculate synthetic seismograms with one-point source model and three-point source model respectively. The AK135 model is employed as a prototype of our numerical global Earth model. The Earth's ellipticity, Earth's medium attenuation, and topography data are taken into consideration. These wave propagation processes are simulated by solving three-dimensional elastic wave governing equations. Three-dimensional visualization of our numerical results displays the profile of the seismic wave propagation. The three-point source, which is proposed from the latest investigations through field observation and reverse estimation, can better demonstrate the spatial and temporal characteristics of the source rupture process than the one-point source. We take comparison of synthetic seismograms with observational data recorded at 16 observatory stations. Primary results show that the synthetic seismograms calculated from three-point source agree well with the observations. This can further reveal that the source rupture process of Wenchuan earthquake is a multi-rupture process, which is composed by at least three or more stages of rupture processes.

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“…With the fast development of computer science and technology, it is viable for researchers to simulate global seismic wave propagation (Komatitsch et al, 2002;Yan et al, 2009;Zhang et al, 2009;Komatitsch et al, 2010;Long et al, 2010). Because of irregular interfaces and rugged free surface of the earth (Komatitsch and Tromp, 2002a, b), traditional finite difference method or pseudo-spectral method with regular grid is not able to correctly fit complex topography (Fornberg, 1987;Moczo et al, 2000;Magnoni et al, 2014).…”

A scheme to treat the singularity in global seismic wavefield simulation using pseudospectral method with staggered grids

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“…Komatitsch and Tromp [8,9] employed a spectral-element method to simulate seismic wave propagation in the whole spherical Earth with the full complexity of 3-D heterogeneity. Yan et al [10] applied this method to model regional wave propagation caused by the Wenchuan earthquake.…”