Interaction of Seismic Waves with Complex Structures.
Abstract
Recent models of earth structure suggest large horizontal gradients, especially in shear velocities. Some changes in existing methods are required to to construct synthetics for broadband signals in many situations, especially when energy can reach the receiver by up-going as well as down going paths. This can be accomplished by allowing locally dipping structure and making some modifications to generalized ray theory. Local ray parameters are expressed in terms of a global reference which allows a de Hoop contour to be constructed for each generalized ray with the usual application of the Cagniard de Hoop technique. Synthetics generated from this method are compared with finite-difference runs using an advanced stable free surface boundary condition where lateral velocity and density variations at the free surface are treated properly. The method is implicit, but only requires a simple pentadiagonal system solver to implement. When coupled with second- and fourth order interior solutions, the overall problems appears to be stable for shear to compressional wave velocity greater than 0.01 and 0.02, respectively. The method is compared with other published algorithms for accuracy and stability. Keywords: Propagation in laterally varying media.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 21, 1985
- Accession Number
- ADA166715
Entities
People
- David G. Harkrider
- Donald V. Helmberger
- Robert W. Clayton
Organizations
- California Institute of Technology