Objective
The objective of the project is to establish a method for calculating traveltimes through a 3-D representation of the seismic velocity structure of central Asia. It is one component of the Lamont-Doherty IMS calibration consortium. The consortium is charged with quantifying the errors in estimated traveltimes for 30 proposed stations in the International seismic Monitoring System (IMS).

Results
Preliminary 3-D IASPEI model (the "A" class of models)
One-dimensional regional velocity models
3-D model of central Asia
Summary of flaws in Bondar's method
Comaprison of different Bondar-style calculations



Links
LDEO Seismic Monitoring
Nuclear Test seismic data repository (W. Y. Kim, LDEO)
P. Richards' consortium page
Prototype International Data Centre (PIDC)
Center for monitoring research (CMR)
Preparatory commision for the CTBT
RUM Upper Mantle model

Note about codes
All the codes for this project are available and reasonably well-documented. After much soul-searching I decided to write most of the mapping functions (coordinate transforms, map plotting, etc.) in Matlab. While Matlab is not as universal as GMT, it is quickly becoming a mainstay at most geophysics institutions. It is simply a more powerful platform for this type of work. In addition to the basic Matlab program, applications from the separate Matlab Mapping Toolbox are used heavily. The scripts provided here were written to conform to the specifications of Matlab version 5.3. They are fully forward compatible with later releases (current release is 6.0 as of June 2001). Matlab code is highly readable so even if these scripts are not used, I hope they can provide a road map of the methods I have used.

The ray tracing software was written by Bill Menke and is distributed freely. See "Three-D raytracing package" at http://doherty.ldeo.columbia.edu/users/menke/software.html. It is written in C and compiles without problems on most systems.