Relationship Between the Process of Large-scale Sediment Movement and Ground Vibration

Hiroshi ASAHARA, Atsuhiko KINOSHITA, Yasutaka TANAKA, Hiroaki SUGAWARA, Gengo YOSHIMURA, Wataru SAKURAI, Teruyoshi TAKAHARA and Soichi KAIHARA

Vibration sensors are expected to be used as an effective means of detecting a large-scale sediment movement triggered by rainfall. However, there is as yet no clear understanding of the relationship between ground vibration and the process of large-scale sediment movement. So we analyzed the relationship, comparing ground vibration of high frequency range (higher than 1 Hz) to vibration of low frequency range (lower than 0.1 Hz) for the Akadani large-scale landslide in Japan in 2011, and comparing video images with seismic data for its re-collapse in 2014. We can explain observation facts consistently, assuming that high frequency vibration is generated by the impact when crushed soil collides with the riverbed or the opposite bank, and that low frequency vibration occurs only when the rock mass slides down without being crushed. High frequency vibration can be used for collapse detection, and the direction of the collapse can be easily estimated using low frequency vibration close to the collapse if it is observed, although low frequency vibration is often not observable due to the collapse process. Furthermore, the detailed process of Akadani landslide was verified from the time difference of vibration observed for each frequency band.

2018/1 380-386