Rock properties and structure within the San Andreas Fault Observatory at Depth (SAFOD) borehole northwest of Parkfield, California: In situ observations of rock deformation processes and fluid-rock interactions of the San Andreas fault zone at ~ 3 km depth

Abstract

The San Andreas Fault Observatory at Depth (SAFOD) is a scientific drilling experiment situated along the central creeping segment of the San Andreas Fault, near Parkfield, California, and north of a segment of the fault that has experienced large historical earthquakes. Drilling into active fault zones allows scientist's to examine in situ rock samples and to record real-time data.

The main goal of this study is to characterize the geologic setting and rock properties of the San Andreas fault at ∼ 3 km depth in the SAFOD borehole. In this region, the fault deforms nearly continuously through aseismic creep and small earthquakes. By sampling and characterizing the rocks from this location of the fault, we can begin to identify the features associated with fault-related deformation processes in the shallow crust; revealing the nature of the earth's crust in the near-fault environment and yields insight into the mechanisms associated with earthquake generation along an active strike-slip fault. It is also useful to seismologists for developing well-constrained, predictive earthquake models.

Project costs are ∼ $175,000 funded primarily by NSF-Earthscope grant EAR- 0454527 to Dr. James P. Evans with additional support provided by the Geology Department and national scholarships to the student. Costs are associated with travel to examine core at the U.S.G.S. Core Lab in Menlo Park, CA and the IODP Gulf Coast Repository in College Station, TX; lab work, and sample processing and analyses at USU and Washington State University; field work travel plus an assistant, and collection and processing of field samples; and expenses associated with Teaching and Research Assistantships appointed to Kelly K. Bradbury during the course of this research.