Japan Geoscience Union Meeting 2023

Presentation information

[E] Online Poster

H (Human Geosciences ) » H-DS Disaster geosciences

[H-DS05] Landslides and related phenomena

Fri. May 26, 2023 3:30 PM - 5:00 PM Online Poster Zoom Room (7) (Online Poster)

convener:Gonghui Wang(Disaster Prevention Research Institute, Kyoto University), Fumitoshi Imaizumi(Faculty of Agriculture, Shizuoka University), Hitoshi SAITO(Graduate School of Environmental Studies, Nagoya University), Masahiro Chigira(Fukada Geological Institute)

On-site poster schedule(2023/5/26 17:15-18:45)

3:30 PM - 5:00 PM

[HDS05-P10] Sliding characteristics of the Dalun Mountain area, Taiwan using dense microtremor data

*Cheng-Feng Wu1, Ruey-Juin Rau1, Ying-Chi Chen1, Chia-Han Tseng2, Jan Burjánek3 (1.Department of Earth Sciences, National Cheng Kung University, 2.Department of Geology, Chinese Culture University, 3.Institute of Geophysics, Czech Academy of Sciences)

Keywords:microtremor measurements, dip slope, Dalun Mountain, Huafan University

The Dalun Mountain area, a dip slope, is a geologically sensitive area with landslides in northern Taiwan. This study deploys microtremor array and single-station measurements, extending from the top of the Huafan University campus to the southwest side, to understand the sliding characteristics around this area. The horizontal-to-vertical spectral ratio, frequency-wavenumber and time-frequency polarization analysis methods are applied to evaluate the landslide thickness, sliding direction and rock mass stability at different slope positions. According to the analysis results, the predominant frequency reflects the depth of the interface between the colluvium and the bedrock (sandstone-shale alternations). Detected sliding depths (15-40 m) were similar to those obtained from well-logging and inclinometer data. In addition, a thicker sedimentary layer appeared at the intersection of the Nanshihkeng Fault and the A Fault at Huafan University. Polarization results also show strong directionality near this intersection point, indicating that this region is relatively unstable, which agrees well with the high strain rates demonstrated by the GPS data. Furthermore, the polarization direction is substantially parallel to the sliding direction (northeast-southwest direction) and perpendicular to the existing surface crack. Besides, we have evaluated the sliding potential at various locations along the slope of Dalun Mountain. Microtremor measurement provides an inexpensive and efficient alternative for investigating the sliding properties of potential landslide areas.