Abstract
Water levels have been continuously recorded since March 1978 in a well in Fremont Valley, where several strands of the adjacent Garlock fault zone have exhibited both left‐lateral displacement and components of normal displacement. Differences in water levels indicate that a fault segment lies between the observation well and a nearby irrigation well. During the 4‐year recording period, six sharp fluctuations, or “spikes,” were noted. These fluctuations, occurring over 2‐ to 4‐day periods, have amplitudes of 15–30 cm. They appear to be the result of creep events on a nearby fault. Two types of creep events are plausible: (1) normal slip on an en echelon trace of the Garlock fault less than 300 m south of the well, with the north side up relative to Fremont Valley or (2) left‐lateral slip on the same fault. Because of the nature of the fluctuations we favor the latter interpretation. Dislocation models utilizing exponential, arc tangent, and skewed cosine functions were used to analyze the water level fluctuations, associated pressure distribution, and fault displacements. The results suggest that creep on the fault ranges from several millimeters to a centimeter for individual events. Estimates of cumulative creep for the period 1978–1982 range from 20 to 50 mm, depending on the particular model employed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.