[HDS14-P11] Earthquake ground motion properties of mountainous district in Totsukawa village, Nara pref. based on the seismic observation – A fundamental study of landslides caused by earthquake –
Keywords:earthquake ground motion, landslide, seismic observation, amplification property, Totsukawa-village, Nara pref.
NARH01, one of the KiK-net observation spots, is situated on the ridge which extends to the east and west direction. Two seismometers are installed on NARH01, one is on the surface and another one is underground of approximately 100-m depth. The geology of this area is accretionary wedge called the Shimanto layer. We installed accelerometers (Hakusan industry JU210) in four places of around NARH01 and started the earthquake observation continuously from November, 2017, in order to supplement the observation data of NARH01 and grasp earthquake ground motion properties at each part of the slope. Setting points of the accelerometers are located at the direct perigee of the NARH01 (823 m above sea level), the east-west point on the eastern ridge along the extension of the ridge line (733 m), the north-south point on the northern slope perpendicular to the ridge line (670 m), and the valley bottom (565 m).
During the observation period over one year, we could observe four small earthquakes that were also observed by NARH01 (one of them is the North Osaka earthquake on June 18th, 2018). The result of Fourier spectrum analysis shows that amplification properties of the earthquake ground motion will be affected by the topography, ground structure, and relative position of epicenter.