Abstract
Investigations of several dam and nuclear sites are summarized for evaluation of fault activity in Japan.
1) In the site Investgation, especially in the area which basement (Tertiary and pre-Tertiary in age) has no sufficient geologic data of relation between faults and Quaternary layer, characteristics of fracture thickness and filled materials of faults may be useful evidence.
2) Fracture thickness and features of looseness of filled materials are considered to correspond to activity of faults.
3) In the absence of sufficiently reliable absolute dating data on evaluation of displacement along faults, a fault which has fracture thickness less than about 1m (in max.) and its filled materials are consolidated or healed will be considered not to be active.
