The binary data will soon be available via anonymous FTP from the National Strong Motion Program FTP-server:
https://ca.water.usgs.gov/nsmp/ in directory GEOS/IZM.
The GEOS Home Page is at /GEOS/geos.html
The URL of this page is /GEOS/IZM/izmit.html
e-mail: glassmoyer@usgs.gov
or address:
Gary Glassmoyer
345 Middlefield Road M/S 977
Menlo Park, California 94025