Figure 1

Map of Kanto Basin, one-way travel time of S waves, best-fitting model functions, and depth variations of S wave velocities. (a) Map showing the Kanto Basin and the locations of 14 seismic observation wells (gray circles), where VSP measurements were carried out. The local variation of sediment-bedrock interface depths from the JIVSM is shown by color gradations. (b) One-way travel times of S waves from the surface to certain depths obtained by VSP measurement at 14 wells (Yamamizu 19962004). (c) Best-fitting exponential asymptotically bounded velocity functions (black lines) to the VSP observations at the Isesaki, Iwatsuki, and Mohka wells (blue lines). (d) Best-fitting exponential asymptotically bounded velocity functions (black lines) to the VSP observations at other wells (blue lines). (e) Depth variations of S wave velocities at 14 wells evaluated by the best-fitting exponential asymptotically bounded velocity functions.