FOCMEC: README

This package contains software for determining and displaying double-couple earthquake focal mechanisms. Input are polarities (P, SV , SH) and/or amplitude ratios (SV/P, SH/P, SV/SH). The main program, focmec (coded in gfortran), performs an efficient, systematic search of the focal sphere and reports acceptable solutions based on selection criteria for the number of polarity errors and errors in amplitude ratios. The search of the focal sphere is approximately equal-area, with selectable step sizes and bounds. The selection criteria for both polarities and amplitudes allow adjustments through weightings for near-nodal solutions.

All paths in this documentation are defined relative to the top directory ./focmec, which is created by uncompressing and expanding the tarball ./focmec.tgz. This file is accordingly ./focmec//doc/focmec.html. The FOCMEC manual is ./focmec//doc/focmec_manual.pdf.

To build the libraries, tables, and executables, it should suffice to go to .focmec//src and (in a Unix system that includes the csh shell) enter ./build_package. The script is set to use the gfortran compiler, so if you are using a different compiler, you have to edit the first few lines so that it defines FCMP appropriately. If the script runs with no errors, the last thing shown on the screen is a compile/link line for program vwbeetle (a test program for the graphics package). Executables and graphics scripts sgfxxx will be in directory ./focmec/bin. Scripts for testing parts of the package are in ./focmec/tests. To delete all executables and libraries, cd to ./focmec/src and enter ./make clean.

To run the FOCMEC package programs from any directory, you must put the executables in your path. For csh or tsch environments, edit ~/.cshrc adding the line

setenv PATH ${PATH}:/usr/local/focmec/bin

For bash, edit ~/.bashrc adding the line

export PATH=${PATH}:$/usr/local/focmec/bin

These lines assume /usr/local/focmec is the address for ./focmec on your computer.

Other documentation

Subdirectories of ./focmec/doc have output files from the test runs done in both ./focmec/tests and ./focmec/sample_runs.

The appropriate reference for this package is

Snoke, J.A. (2003). FOCMEC: FOcal MEChanism determinations. International Handbook of Earthquake and Engineering Seismology (W.H.K. Lee, H. Kanamori, P.C. Jennings, and C. Kisslinger, Eds.), Academic Press, San Diego, Chapter 85.12.