Spectral-element simulations of global seismic wave propagation—I. Validation

• Published in: Geophysical journal international Vol. 149; no. 2; pp. 390 - 412
• Main Authors: Komatitsch, Dimitri, Tromp, Jeroen
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2002; Blackwell Science Ltd; Oxford University Press (OUP)
• Subjects: body waves; Computer Science; Distributed, Parallel, and Cluster Computing; elastodynamics; global seismology; numerical techniques; seismic wave propagation; surface waves
• ISSN: 0956-540X; 1365-246X
• DOI: 10.1046/j.1365-246X.2002.01653.x

We use a spectral-element method to simulate seismic wave propagation throughout the entire globe. The method is based upon a weak formulation of the equations of motion and combines the flexibility of a finite-element method with the accuracy of a global pseudospectral method. The finite-element mesh honours all first- and second-order discontinuities in the earth model. To maintain a relatively constant resolution throughout the model in terms of the number of grid points per wavelength, the size of the elements is increased with depth in a conforming fashion, thus retaining a diagonal mass matrix. In the Earth's mantle and inner core we solve the wave equation in terms of displacement, whereas in the liquid outer core we use a formulation based upon a scalar potential. The three domains are matched at the inner core and core–mantle boundaries, honouring the continuity of traction and the normal component of velocity. The effects of attenuation and anisotropy are fully incorporated. The method is implemented on a parallel computer using a message passing technique. We benchmark spectral-element synthetic seismograms against normal-mode synthetics for a spherically symmetric reference model. The two methods are in excellent agreement for all body- and surface-wave arrivals with periods greater than about 20 s.