PubTalk 10/2002 — Plumbing the Mysteries of the San Andreas Fault

Deep Drilling to Test Fundamental Theories About Faulting and Earthquakes

By Stephen H. Hickman, Geophysicist

• Scientists will make measurements, obtain samples and place instruments directly within the fault at a depth of 2.5 miles, creating the San Andreas Fault Observatory at Depth (SAFOD)
• SAFOD's instruments will continuously measure fluid pressure, deformation, temperature, and seismic shaking through multiple earthquake cycles
• A 1.4-mile-deep pilot hole drilled this summer is already providing earthquake data; Congressional approval is pending for the deeper SAFOD hole
• Data from these drill holes are providing a third dimension to the ongoing Parkfield Earthquake Experiment (see http://quake.usgs.gov/research/parkfield)
• Learning what really happens in the fault zone before, during,and after earthquakes will help scientists betterpredict the timing and severity of future quakes