Figure 3
Spatial distributions of stresses determined using the multiple inverse method. The epicentres of the 164 seismic events examined are marked by colored circles. When a stress with a misfit of <30° is judged to be compatible with a fault-slip datum8, either or both of the stresses explain slip vectors on one of the nodal planes for 164 of the 188 events. Of the 164 events, only 36 are compatible only with a single principal stress, as the stress tensor inversion based on the Wallace–Bott hypothesis11,12 provides rather loose constraints on the fit of a stress to a fault-slip datum13. “All stresses” means that all the stresses can explain the slip vectors of the seismic events. “No Stress C” means that Stresses A and B can explain the slip vectors of the seismic events. Grey dots indicate the epicentres of nonvolcanic tremors in southwestern Japan for the period 2001 to 200932. Depth contours indicate the upper surface of the Philippine Sea plate33. LPZ, Low permeable anisotropy zone (Gary dot region). CSP, Convex slab point.
