Summary

Earthquake disaster never occurs whenever seismic force does not surpass durability of ground and structures. Thus continuous watch of earthquake motion is first of all necessary, in order to predict and monitor the occurrence of earthquake disaster. For the ground and structures exposed to earthquake motion, it is necessary to grasp their durability precisely by executing investigations in advance. From the view point of earthquake disaster prevention, to grasp the durability of ground and structures is even more important than to monitor the earthquake motion. In this paper, a new technique to investigate rapidly with precision durability against earthquake of various structures and surface ground by using microtremor. Validity of the proposed method has been examined by comparing the results of investigations by the new technique in the earthquake damaged areas (before or after the event) with actual earthquake damage experienced. If weak points of structures can be detected in advance by investigating the durability of various structures and ground, damage of structures can be decreased by taking appropriate countermeasures. Besides, secondary disaster can be also decreased very much by adopting precise immediate measures based upon accurate damage estimation when earthquake occurs