Benchmark Study of a 3d Parallel Code for the Propagation of Large Subduction Earthquakes

Abstract

Abstract. Benchmark studies were carried out on a recently optimized parallel 3D seismic wave propagation code that uses finite differences on a staggered grid with 2 nd order operators in time and 4 th order in space. Three dual-core supercomputer platforms were used to run the parallel program using MPI. Efficiencies of 0.91 and 0.48 with 1024 cores were obtained on HECToR (UK) and KanBalam (Mexico), and 0.66 with 8192 cores on HECToR. The 3D velocity field pattern from a simulation of the 1985 Mexico earthquake (that caused the loss of up to 30000 people and about 7 billion US dollars) which has reasonable agreement with the available observations, shows coherent, well developed surface waves propagating towards Mexico City.

Low-Frequency 3D Wave Propagation Modeling of the 12 May 2008 Mw 7.9 Wenchuan Earthquake

“…An important result of those studies was that, even though theoretically the computed synthetic seismograms (Cabrera, et al, 2007;Chavez et al, 2008) for the 0.5 and 0.25-km spatial discretization should have a frequency content larger than 1 Hz, the Fourier amplitude spectra of the corresponding synthetics had very small values at a frequency of ∼0:3 Hz (< 0:5 Hz) for all the previously mentioned space and temporal discretizations. This result is in agreement with Mendoza and Hartzell (1989), who emphasized the 0.5-Hz limit of their source inversion.…”

“…The 3DOPFD code previously has been successfully used to obtain near-field and far-field low-frequency synthetics of the 19 September 1985 M s 8.1 Michoacan, Mexico, earthquake (Cabrera, et al, 2007;Chavez et al, 2008). For those studies, the authors used the slip distribution suggested by Mendoza and Hartzell (1989), who, for the source inversion of the 1985 Michoacan event, used nearfield and teleseismic waveform data low-pass filtered at 0.5 Hz and utilized 120 subfaults of 15 × 13:9 km 2 , each of them to obtain the slip distribution of the event.…”

“…Herewith, first a synthesis of the elastodynamic formulation (based on Minkoff, 2002) and a description of the 3D optimized parallel algorithm (Cabrera et al, 2007;Chavez et al, 2008) of the elastic wave propagation problem are presented.…”

“…Other details about the implementation, tests, and benchmark studies performed on different supercomputer platforms of the developed 3DOPFD optimized code can be found in Cabrera et al (2007) and Chavez et al (2008).…”

“…In this work, a recently optimized 3D seismic wave propagation parallel finite-difference (3DOPFD) code (Cabrera et al, 2007;Chavez et al, 2008), based on the staggered finite-difference method proposed by Madariaga (1976) for the simulation of the dynamic propagation of a circular fault, was used to obtain low-frequency (≤ 0:3 Hz) 3D velocity synthetics of the 12 May 2008 M w 7.9 Wenchuan earthquake. The supercomputers KanBalam and HECToR (see Data and Resources section) were used to run the code.…”