The San Andreas Fault runs northwest through eastern Monterey County. The little town of Parkfield (Population 37) sits astride the fault, and for many years has been heavily instrumented in hopes of catching the forerunners of the next major earthquake. Scientists were hopeful. because the Parkfield section of the fault had experienced a major earthquake at fairly regular intervals of about 22 years.
Based on the 22-year cycle, and the 1966 earthquake, it was hoped that the (anticipated) 1988 temblor could be caught in the act. The hills around Parkfield are studded with laser reflectors, whose distances from the central observatory on Gold Hill can be measured to the millimeter. Up through 1992, the USGS sponsored detailed recordings of all manner of earthquake precursors, including distance measurements from Gold Hill to the reflectors; strain gauges throughout the valley; sensors down all the wells; and an earthquake awareness program among the valley's residents, in which they were asked to watch out for subtle changes such as doors and gates sticking or swinging more easily, odd behavior by animals, and anything else that might warn of an approaching earthquake.
Finally, though, the funding ran out, and the 1988 earthquake never happened.
Recent earthquake activity in the Parkfield area can be viewed by visiting the USGS site.