TITLE: San Andreas Park: drilling the fault to solve the physics of plate boundary paradoxes.

SPEAKER: Professor Peter E. Malin,

The San Andreas fault has moved southern California north some 300-400 km in the past 15 million years. The resulting grinding of rocks should have produced a sizable heat flow out of the fault, but this is not observed. To solve this paradox (and a few others), a borehole will be drilled several kilometers down into the fault to retrieve fault rock and make physical measurements of the stress-strain cycle of small repeating earthquakes. The mechanics of the paradox may involve fluids trapped in the fault, changes in normal stress under earthquake vibration, or unusual fault materials. Despite its expense (>$5M) the borehole is essential since surface measurements have not only failed to supply the key information needed to solve the paradox, but clouded the issue in several other controversies. San Andreas Park should open for drilling in the Fall of 2001. Will the Park accidentally let the "big one" loose? Another paradox lets seismologists off this potentially catastrophic outcome of their curiosity about the currently most dangerous fault in the US.