Preprints
https://doi.org/10.5194/esurf-2020-94
https://doi.org/10.5194/esurf-2020-94

  02 Dec 2020

02 Dec 2020

Review status: this preprint is currently under review for the journal ESurf.

Locating rock slope failures along highways and understanding their physical processes using seismic signals

Jui-Ming Chang1, Wei-An Chao2,3, Hongey Chen1,4, Yu-Ting Kuo5, and Che-Ming Yang6 Jui-Ming Chang et al.
  • 1Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan
  • 2Department of Civil Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
  • 3Disaster Prevention and Water Environment Research Center, National Chiao Tung University, Hsinchu 30010, Taiwan
  • 4National Science and Technology Center for Disaster Reduction, New Taipei 23143, Taiwan
  • 5Department of the Earth and Environmental Sciences, National Chung‐Cheng University, Chia-yi County 621, Taiwan
  • 6Department of Civil and Disaster Prevention Engineering, National United University, Miao-Li 36003, Taiwan

Abstract. Regional monitoring of rock slope failures by the seismic technique is rarely studied due to significant source location errors, and it still lacks the signal features needed for understanding events of this type because of the complex mass movement involved. To better understand events of this type, ten known events along highways in Taiwan were analyzed. First, a hybrid approach (GeoLoc) composed of cross-correlation-based and amplitude-attenuation-based approaches was applied, and it produced a location error of maximum 3.19 km for the ten events. Then, we analyzed the ratio of local magnitude (ML) and duration magnitude (MD) and found that a threshold of 0.85 yields successful classification between rock slope failure and earthquake. Further, the GeoLoc can retrieve the seismic parameters, such as signal amplitude at the source (A0) and ML of events, which are crucial for constructing scaling law with source volume (V). Indeed, Log(V) = 1.12 ML + 3.08 and V = 77,290 A00.44 derived in this study provide the lower bound of volume estimation, since the seismic parameters based on peak amplitudes cannot represent the full process of mass loss. Second, while video records correspond with seismic signals, the processes of toppling and sliding present column- and V-shaped spectrograms, respectively. The impacts of rockfall directly link directly to the pulses of seismic signals. Here, all spectrogram features of events can be identified by event volumes larger than 2,000 m3, corresponding to the farthest epicenter distance ~2.5 km. The previous results were obtained using the GeoLoc scheme for providing the government rapid reports for reference. Finally, a recent event on 12th June 2020 was used to examine the GeoLoc scheme’s feasibility. We estimated the event's volume by the two scalings: 3,838 m3 and 3,019 m3, which was roughly consistent with the volume estimation of 5,142 m3 from the digital elevation model. The physical processes, including rockfall, toppling, and complex motion behaviors of rock interacting with slope inferred from the spectrogram features were comprehensively supported by the video record and field investigation. We also demonstrated that the GeoLoc scheme, which has been implemented in Sinwulu catchment, Taiwan, can provide fast reports, including the location, volume, and physical process of events of this type to the public soon after they occur.

Jui-Ming Chang et al.

 
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Jui-Ming Chang et al.

Data sets

Seismic data.rar Jui-Ming Chang https://doi.org/10.6084/m9.figshare.12203258

Broadband Array in Taiwan for Seismology Academia Sinica, Institute of Earth Sciences https://doi.org/10.7914/SN/TW

Video supplement

Movie for rock slope failure Jui-Ming Chang https://doi.org/10.6084/m9.figshare.13168427.v1

Jui-Ming Chang et al.

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Short summary
Seismic techniques applied in rock slope failures do not provide rapid notifications, such as earthquakes, due to the lack of connections between seismic signals and events. We studied ten known events in Taiwan and developed a GeoLoc scheme to locate rock slope failures, estimate the event volume, and understand their physical process by available videos. With real-time seismic data transmission, a rapid report can be created within several minutes after the event to the public.