**Principal Investigator**
Takashi Furumura **Project** u55

Research School of Earth Sciences and **Machine
**CM

Hokkaido University of Education

**Co-Investigator** B L N
Kennett

Research School of Earth Sciences

**3-D Modeling of Seismic Save Propagation**

A parallel pseudospectral method for seismic wave propagation in heterogeneous medium is developed. The pseudospectral method is an high-accuracy numerical modeling technique which requires less computer memory and time than traditional techniques such as the finite-difference method. However, the application of the pseudospectral modeling for a reasonable scale problem is still computationally very intensive. To overcome this we have developed a parallel pseudospectral code for calculating the 3-D wavefield concurrently by use of a number of processors. The parallel algorithm is based on a partition of the computational domain distributed across a number of processors and calculating the wavefield in the subdomains with interprocessor communications. Experimental performance test using the 32-node Thinking Machine CM-5 parallel-computer achieved a significant speed-up rate of 26 compared with the previous conventional computation on a single processor, which agreed very well with theoretical parallel performances predicted from a knowledge of the ratio of the computation time to the communication speed for each system.