Detailed crustal structures in the northwestern part of the central Japan were obtained by taking recent detailed gravity data, crustal structure derived from the Atsumi- Noto explosion and geological information into consideration.
As the results, (1) undulation of the Moho derived from distribution of 1°×1°mean Bouguer anomaly agreed with that derived from explosion seismology; (2) the short wavelength Bouguer anomaly of less than 60km could be explained by the configuration of the crustal structure shallower than 10km. Therefore, the large negative Bouguer anomaly in the central part of the Japanese islands is presumably explained not only by undulation of the Moho but also by that of the shallower layers within the crust.