17:15 〜 18:45
[HDS08-P19] Ultra-dense seismic observation in and around a seashore landslide
In the stability analysis for earthquake-induced landslides, Newmark method and FEM (finite element method) are often used. These approaches set simple assumptions: a landslide is a rigid body for Newmark, and simple internal structure and topography are modeled for FEM. However, actual landslides have complicated topography and strong heterogeneity, which produces scattering waves and makes the seismic force incoherent inside the landslide. In order to grasp the propagation characteristics of the seismic waves in and around the landslide and to sophisticate the earthquake-induced landslide stability analysis, we performed ultra-dense seismic observation in and around a seashore landslide in southeastern Hokkaido, Japan.
The target landslide has the length and the width with 60 m and 20 m, respectively. 21 seismometers were settled with the spacing ~ 5-10 m in and around the landslide and the seismic waveforms are continuously recorded from July 2023. The spectra for the S-wave parts from the nearby earthquakes show variety among the stations even inside the landslide, but are stable among different earthquakes. This means that seismic amplification is different inside the landslide, suggesting that internal deformation should be recognized during the propagation of the seismic waves.
The target landslide has the length and the width with 60 m and 20 m, respectively. 21 seismometers were settled with the spacing ~ 5-10 m in and around the landslide and the seismic waveforms are continuously recorded from July 2023. The spectra for the S-wave parts from the nearby earthquakes show variety among the stations even inside the landslide, but are stable among different earthquakes. This means that seismic amplification is different inside the landslide, suggesting that internal deformation should be recognized during the propagation of the seismic waves.