There is no geological evidence of the eastern continuation of the Sanchu Graben Zone (SGZ) except for a local Cretaceous sediment found in the eastern margin of the Kanto Mountains, Central Japan. SGZ and its continuation are presumed to have developed along an axis of the geosynclinal movement. Such an axis can be detected generally as a linear arrangement of local Bouguer gravity anomaly lows. We detected some mutually parallel lineaments in the eastern part of the Kanto Mountains by means of the line-detection method applied to Bouguer anomaly data digitalized with a 500-m grid interval. We conclude that one of them, which runs on the extension of SGZ, may possibly correspond to the eastern continuation of SGZ.
