The Crustal Deformation project provides continuous high-precision deformation, magnetic field, and seismicity data mostly from deep-borehole strain instruments before, during and after earthquakes and volcanic activity in the United States. The primary geophysical objectives for this experiment are to identify how faults and volcanoes fail, how earthwuakes and eruptions start, and what are the critical material properties, including the role of fluids, that control this hazardous behaviour. Data are immediately available through digital satellite telemetry to the public and researchers throughout the world over the Internet.

The instruments deployed in this experiment include creepmeters, strainmeters, tiltmeters, magnetometers, water level monitors, two-color geodimeters, and GPS receivers. For information about each of these instrument types, follow the links to the left.

Data from most of the instruments are transmitted using 16-bit digital telemetry every 10 minutes to a host computer in Menlo Park. The data are also recorded on-site on analog and 16-bit digital recorders together with seismic velocity and acceleration data. Removal of re-zeros, offsets, problems with telemetry and identification of instrument failures is a difficult, tedious and time consuming task. In order to have a relatively up-to-date file of data a computer algorithm has been written that accomplishes most of these tasks most of the time. Detailed discussion or detailed analysis usually requires hand checking of the data. Data are also transmitted in digital form on seismic channels from some sites to provide continuous information in the period band 1 to 1000 seconds.

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