Modern Seismic Travel Time Tables and Station Corrections for P and S waves
Abstract
(1) We refine estimates of inner core structure by examining PKP travel times and find that anisotropy is a simpler explanation than heterogeneity for the observed residual patterns. Our preferred model of inner core anisotropy contains velocities that are 0.5% faster in a N-S direction than an E-W direction. (2) We study various mantle differential travel times including SS-S, ScS-S, PP-P, and PcP-P and compare these results to those obtained from handpicked waveform data. Large-scale coherent patterns of residuals are seen which indicate,mantle heterogeneity. (3) We examine PKP travel times to study the possibility of outer core heterogeneity models which are suggested by observations of anomalous splitting in normal modes. We find that the travel times limit the scale of possible outer core heterogeneity to models much smaller than those required to explain the mode splitting data. (4) We develop computer codes which return travel time and ray geometries for a given seismic phase, source-receiver pair, and arbitrary 3-d earth models specified by their spherical harmonic expansions. Seismic travel times, Earth models, Core structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 13, 1992
- Accession Number
- ADA262536
Entities
People
- John A. Orcutt
Organizations
- Scripps Institution of Oceanography