Structure of seismogenesis along a segment of the San Andreas Fault in central California. This figure shows a comparison of the non-volcanic tremor (NVT) zone and seismogenic zone along the San Andreas Fault (SAF) (modified from Shelly and Hardebeck (2010); segment location shown in Figure 1). The star represents the hypocenter of the 2004 M6 Parkfield earthquake, and the shading shows the area of its combined coseismic slip and first 230 days of postseismic slip (Murray and Langbein 2006). Blue dots represent the hypocenters of regular earthquakes provided by D. Shelly. Red and green circles are ambient and teleseismically triggered tremor from Waldhauser and Schaff (2008) and Peng et al. (2009), respectively. The Moho depth is about 25 km (dashed line). Magenta line shows the projected location and maximum depth of the SAFOD scientific drill hole.