SAN RAFAEL, Calif. -- Scientists searching for ways to predict the next major Bay Area earthquake took their quest to Marin's Lucas Valley Wednesday, using a 40-foot tall drilling rig to dig deep into the earth to check on the movement of the plate boundary.

Geologist Andy Tiedeman said sensors would be used to detect even the slightest movement of the earth. They will be placed 800-feet under the surface.

"The end game is to eventually predict earthquakes," said Tiedeman of his group's efforts.

In nearby downtown San Rafael, residents were surprised that researchers had selected Lucas Valley and not more well-known earthquake threat locations on the San Andreas Fault in the South Bay or the Hayward Fault in the East Bay.

"The fault does not run through San Rafael," said Marla Mulligan, a local resident. "I would think more like Hayward or San Andreas."

But researchers say this study is not targeting faults, but the plate boundary -– a vast swath of deformed Pacific Coast crush.

UC Berkeley Geophysicist Peggy Hellweg said measuring stresses deep in the earth hold the key to predicting quakes.

"Why are there earthquakes?" Hellweg said. "Can we see something that happens before an earthquake? Perhaps?"

The researchers say they will be drilling the hole in Lucas Valley for a week and then move on to the East Bay. Overall, the National Science Foundation will be funding some 80 bore holes to be drilled in earthquake prone areas.