In:
Earth Surface Dynamics, Copernicus GmbH, Vol. 9, No. 3 ( 2021-06-07), p. 505-517
Abstract:
Abstract. Regional monitoring of rock slope failures using the seismic technique is rarely undertaken due to significant source location errors; this method also still lacks
the signal features needed to understand events of this type because of the complex mass movement involved. To better comprehend these types of events, 10 known events along highways in Taiwan were analyzed. First, a hybrid method (GeoLoc) composed of cross-correlation-based and
amplitude-attenuation-based approaches was applied, and it produced a maximum location error of 3.19 km for the 10 events. We then
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, 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, as the seismic parameters based on peak amplitudes cannot represent the full process of mass loss. Second, while video records
correspond to seismic signals, the processes of toppling and sliding present column- and V-shaped spectrograms, respectively. The impacts of
rockfall link directly to the pulses of seismic signals. Here, all spectrogram features of events can be identified for events with volumes larger than
2000 m3, corresponding to the farthest epicenter distance of ∼ 2.5 km. These results were obtained using the GeoLoc
scheme for providing the government with rapid reports for reference. Finally, a recent event on 12 June 2020 was used to examine the GeoLoc scheme's
feasibility. We estimated the event's volume using two scalings: 3838 and 3019 m3. These values were roughly consistent with the volume
estimation of 5142 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 Sinwulyu catchment, Taiwan, can provide fast reports,
including the location, volume, and physical process of events, to the public soon after they occur.
Type of Medium:
Online Resource
ISSN:
2196-632X
DOI:
10.5194/esurf-9-505-2021
DOI:
10.5194/esurf-9-505-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2736054-4
Permalink
