FINITE-DIFFERENCE COMPUTATION OF TRAVELTIMES IN VERY CONTRASTED VELOCITY MODELS - A MASSIVELY PARALLEL APPROACH AND ITS ASSOCIATED TOOLS

被引:686
作者
PODVIN, P [1 ]
LECOMTE, I [1 ]
机构
[1] INST PHYS GLOBE STRASBOURG, SISMOL LAB, F-67084 STRASBOURG, FRANCE
关键词
FINITE DIFFERENCE; MASSIVELY PARALLEL COMPUTATION; RAY TRACING; SEISMIC WAVES; TRAVELTIMES;
D O I
10.1111/j.1365-246X.1991.tb03461.x
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We present a new massively parallel method for computation of first arrival times in arbitrary velocity models. An implementation on conventional sequential computers is also proposed. This method relies on a systematic application of Huygens' principle in the finite difference approximation. Such an approach explicitly takes into account the existence of different propagation modes (transmitted and diffracted body waves, head waves). Local discontinuities of the time gradient in the first arrival time field (e.g., caustics) are built as intersections of locally independent wavefronts. As a consequence, the proposed method provides accurate first traveltimes in the presence of extremely severe, arbitrarily shaped velocity contrasts. Associated with a simple procedure which accurately traces rays in the obtained time field, this method provides a very fast tool for a large spectrum of seismic and seismological problems. We show moreover that this method may also be used to obtain several arrivals at a given receiver, when the model contains reflectors. This possibility significantly extends the domain of potential geophysical applications.
引用
收藏
页码:271 / 284
页数:14
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