Inferred seismic slip rate for major faults, and their association with larger historical events and historical seismicity as of 2006. Red sources slip at a high rate and are presently locked, and thus are accumulating tectonic strain to be released in future large earthquakes; white sources have low seismic slip rates, so most of their slip occurs as creep and they are unlikely to be sites of future large earthquakes. The red zone marked 1938 is thought to have since ruptured in the Tohoku earthquake. Source: Stein et al. ; modified from Nishimura et al. .