STRONG MOTION ESTIMATION IN ORITATE DISTRICT, SENDAI CITY, FOR THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE BASED ON EXTENDED SITE EFFECT SUBSTITUTION METHOD

Abstract

 A large scale landslide was triggered at an embankment in Oritate area, Sendai City, during the 2011 off the Pacific coast of Tohoku Earthquake. In this study, to estimate ground motions during the main shock at the landslide site by means of an improved version of the site effect substitution method that has been developed by the authors, we performed microtremor measurement and temporary aftershock observation at the site. Through this approach, we estimated the seismic waveforms for the site of a strong motion station, which showed good consistency with the recordings obtained by this station, indicating the validity of the method. Then we used this improved method to estimate the strong ground motions at the landslide site. The estimated seismic waveforms include larger high-frequency components than those observed at neighboring strong motion stations.