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Schematic of SAFOD and the SAFOD pilot hole, superimposed on electrical resistivity structure inferred from surface surveys. Approximate locations of small earthquakes are shown as white dots, with the location of the SAFOD target earthquakes in red. The SAFOD pilot hole was drilled in the summer of 2002 to a depth of 2.2km. Drilling of the main SAFOD hole began in June 2004, and an extensive program of downhole measurements, spot coring and fluid sampling will be conducted during drilling. Following a two-year period of downhole monitoring, four 250-m-long core holes (shown in black) will be drilled off the main hole to obtain samples from the most active portions of the fault zone. SAFOD will then be instrumented with downhole sensors (red ovals) for long-term monitoring of seismicity, deformation, fluid pressure and temperature. The surface locations of the pilot hole and SAFOD are within 10 m of each other, and are separated here only for clarity.
Courtesy of EarthScope.
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