Slip-rate increase at Parkfield in 1993 detected by High-Precision EDM and Borehole Tensor Strainmeters

摘要: On two of the instrument networks at Parkfield, California, two-color Electronic Distance Meter (EDM) network and Borehole Tensor Strainmeter (BTSM) network, we have detected a rate change starting in 1993 that has persisted least 5 years. These other instruments capable measuring crustal deformation were installed Parkfield anticipation moderate, M6, earthquake on San Andreas fault. Many these been operation since mid 1980s established an excellent baseline to judge changes coherence such between instruments. The onset observed corresponds time Parkfield. From late 1992 through 1994, region had increase number M4 M5 earthquakes relative preceding 6 deformation-rate also coincides with end 7-year period sub-normal rainfall. Both spatial hydrological modeling suggest tectonic explanation for change. observations, infer slip increased over 1993–1998.