Atera Fault and Its Displacement Vectors
The northwest-southeast-trending Atera fault, which is expressed geomorphologically and geologically, cuts many terraces of the Kiso River in central Japan. The authors measured the vertical and horizontal displacement of the fault from the offset of the terrace surfaces and faces (scarps). Seven displacement vectors were calculated in the fault plane. They show that (1) the horizontal displacement is about five times larger than the vertical; (2) the faulting, to date, has been consistently left lateral; (3) the rate of faulting seems to have been almost consistent (about 2–4 m/1000 yrs.). It is noted that the Neo Valley fault is subparallel to the Atera fault, and that its displacement is also left lateral. Data on recent strike-slip fault displacements in central Japan, in part from this specific study, show a regular pattern of geographic distribution of strains.