We have investigated the distribution and properties of the ground deformations, associated with topography and ground conditions, which were caused by the Southern Hyogo Prefecture Earthquake, in the southeastern area of the Rokko Mountains.
The landform of the study area is characterized by hill formed by the Higher terrace plane (Takakura Plane) and Middle terrace plane (Uegahara Plane), and the Koyo Fault, which is considered to be an active fault, striking in the trend of a NE to SW direction in the northwestern area.
There has been rapid improvement in recent years to irrigation ponds and valleys through land reclamation and subsequent regional development in this area.
The ground deformations caused by the earthquake can be classified into three large groups as follows:
1. Liquefaction and accompanied ground deformation caused by seismic vibration in reclaimed land on irrigation ponds and valleys.
2. Slope failure in the fills in residential district.
3. Landslide and land subsidence caused by ground fluidization in the fills and Alluvium.
These deformations appear to be concentrated along the Koyo Fault and the interpretable lineament which runs in the trend of a ENE to WSW direction in the southeastern area of the Koyo Fault.
Furthermore, most deformations did not occur in the natural slopes but rather in those sections, which were formed artificially, such as reclaimed lands and fills.
The results of this study shall be taken into consideration when examining the disaster prevention in future earthquake in hill areas.
