断層モデルと地表変位のパターン

抄録

Displacement field due to some typical dimensional faults in a semi-infinite medium are shown systematically, by exhibiting contour maps for vertical components and vector maps for horizontal components, which provide helpful guide when estimating focal parameters such as dip-angle and slip direction from observed data on static deformations.
Computations and mappings are carried out by the machine program developed by SATO and MATSU'URA (1974).
For a pure dip-slip reverse fault (Fig. 3), main upheaval appears on the area of projection of the fault to the surface and spreads over the hanging wall side as the dip-angle increases. For small dip-angle, subsidence is found on the hanging wall side, while for large dip-angle, it is observed on the foot wall side.
For a pure strike-slip fault (Fig. 4), there appear subsidence and upheaval at two ends of the fault projection. As the dip-angle increases, the area with opposite deformation to that on the hanging wall side spreads on the foot wall side.
Horizontal displacements do not show quite a different pattern between fault models with different slip directions (Fig. 6). Hence it may be difficult to get unique fault solution from observation of only horizontal displacements unless precise and dense data around the fault are available.