October 2017 by Arthur Snoke (snoke@vt.edu)

This package contains software for determining and displaying double-couple
earthquake focal mechanisms. Input are polarities (P, SV , SH) and 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
uniform in angle, with selectable step size and bounds for three
angles. The selection criteria for both polarities and angles allow adjustment 
through weightings for near-nodal solutions. Published applications include 
determinations of best-constrained fault-plane solutions for suites of 
earthquakes recorded at local to teleseismic distances and the use of recorded 
polarities and relative amplitudes to produce waveform synthetics.

The package as distributed is a gzipped tar file: focmec.tgz. On Unix, one can 
both uncompress and expand this file with a single command:    

      tar -xzf focmec.tgz

or, if you are using an older version of tar that does not recognize -z,

      gzip -d -c focmec.tgz | tar -xf - 

This operation produces a directory tree topped by ./focmec. Instructions for 
building and testing the package are in HTML format.  One starts by opening
./focmec/doc/focmec.html.  Included among the links is one to the manual: 
./focmec/doc/focmec_manual.pdf.  For those who used earlier versions of the FOCMEC package, there have been a few changes in formatting and procedures.  See ./focmec/doc/update.html for a summary of changes.