VIBRATION CHARACTERISTICS OF NIKKO-ZAN RIN-NOJI TEMPLE HONDO FOR THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE AND ITS AFTERSHOCKS

This paper describes vibration characteristics of Nikko-zan Rin-noji temple Hondo (main hall) for the 2011 off the Pacific coast of Tohoku Earthquake and its aftershocks. From rare records observed in the traditional wooden structure, the characteristics are identified by the forgetting factor recursive least squares method. In the first translational mode, the natural frequency decreases and the damping factor increases with increasing deformation. It is expected that the nonlinearity is recoverable, because the results of microtremor measurements almost never change before and after the mainshock. The vibration characteristics in torsional mode show independency on increasing deformation.