首都圏北部で発生する強震動の方向  [in Japanese] Direction of the severe shocks of earthquakes in the northern part of the metropolitan area, Japan  [in Japanese]

Three underground fault systems are developed in the western part of the Kanto Plain. The pre-Quaternary basement is cut by these fault systems. Many fault blocks are formed with the basement, we have had there frequent severe earthquakes in this area. The Nishi-Saitama earthquake was happened in 1931. It was the sharpest earthquake we have experienced for some ten years past. Many gravestones which were planted in the abovementioned fault blocks have overturned in the same direction by this violent earthquake. Its situation was suddenly shifted on the boundary of the fault blocks. From this fact, it is supported that each fault block shakes in different direction by severe earthquake.