San Andreas Fault Observatory at Depth

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Schematic representation of the SAFOD borehole and pilot hole.

The San Andreas Fault Observatory at Depth (SAFOD) is one of three components of the Earthscope Project, funded by the National Science Foundation in conjunction with the USGS and NASA. The SAFOD site is located just north of the town of Parkfield, California. The SAFOD main hole was drilled to a depth of about 3.4 km in 2004 and 2005, crossing the San Andreas Fault near a region of the fault where repeating Magnitude 2 earthquakes are generated.

A goal of this project is to install instruments to record data near the source of these earthquakes. In addition to the installation of these instruments, rock and fluid samples were continuously collected during the drilling process, and will also be used to analyze changes in geochemistry and mechanical properties around the fault zone. The project will lead to a better understanding of the processes that control the behavior of the San Andreas fault, and it is hoped that the development of instrumentation and analytic methods will help evaluate the possibility of earthquake prediction.

Drilling began in 2004 and was completed in three phases. Phase 1 was completed when the hole was drilled to a vertical depth 1,500 m (4,900 ft), and then the trajectory of the hole was angled toward the fault. In the summer of 2005 Phase 2 drilled to a depth around 3 km, passing the San Andreas fault. Phase 3 involved the collection of 1,600 m (5,200 ft) of core from active areas of the fault and was completed on 15 September, 2007. Following the completion of phase 3, instruments were placed in the hole to monitor the long-term behavior of the fault.

The SAFOD observatory is in operation. All data collected at SAFOD as part of the EarthScope project are open and freely available to all interested researchers. The Northern California Earthquake Data Center at U.C. Berkeley is the principal data repository for these SAFOD data. Several terabyte of assembled data collection are also available at the IRIS DMC.

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References[edit]

  • Ellsworth, W.L.; S.H. Hickman, M.D. Zoback. Seismology in the Source: The San Andreas Fault Observatory at Depth. 
  • Ellsworth, W.; S. Hickman; M. Zoback; E. Davis; L. Gee; R. Huggins; R. Krug; C. Lippus; P. Malin; D. Neuhauser (2005). "Observing the San Andreas Fault at depth". Eos, Transactions, American Geophysical Union 86: 52. 
  • Zoback, M. D (1998). "Scientific drilling into the San Andreas fault and site characterization research: Planning and coordination efforts. Final technical report". 
  • Zoback, M.D.; S.H. Hickman, W. Ellsworth (2002). "The San Andreas Fault Observatory at Depth (SAFOD): testing fundamental theories of earthquake mechanics". 2002 Denver Annual Meeting. 
  • Zoback, M. (2003). "Scientific Drilling into the San Andreas Fault: The SAFOD Experiment". AAPG Annual Meeting 2003. 
  • Zoback, M.D.; S. Hickman; W. Ellsworth (2005). "Overview of SAFOD Phases 1 and 2: Drilling, sampling and measurements in the San Andreas Fault zone at seismogenic depth". Eos, Transactions, American Geophysical Union 86: 52. Bibcode:2005EOSTr..86...52H. doi:10.1029/2005EO050006. 
  • Zoback, M.D.; S.H. Hickman, W. Ellsworth, D. Kirschner, N.B. Pennell, J. Chery, S. Sobolev (2007). "Preliminary Results from SAFOD Phase 3: Implications for the state of stress and shear localization in and near the San Andreas Fault at depth in central California". American Geophysical Union, Fall Meeting 2007, abstract# T13G-03. 
  • Zoback, Mark D.; Hans-Peter Harjes. Injection-induced earthquakes and crustal stress at 9 km depth at the KTB deep drilling site, Germany. Retrieved 2009-03-28. 
  • EarthScope (2008). "EarthScope: SAFOD Observatory". EarthScope. Retrieved 2009-03-28. 
  • GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany (2006-10-31). "ICDP - International Continental Scientific Drilling Program". German Continental Scientific Deep Drilling Program. Retrieved 2009-03-28. 
  • "KTB Deep Crustal Laboratory of GFZ". KTB Deep Crustal Laboratory of GFZ. 2006. Retrieved 2009-03-28. 
  • USGS; NSF (2009-01-29). "San Andreas Fault Observatory at Depth". San Andreas Fault Observatory at Depth. Retrieved 2009-03-28. 

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