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

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.

Towards a rapid assessment of highway slope disasters by using multidisciplinary techniques

“…1a). In our case, only two detected stations cannot offer the accurate location, which is demonstrated by Chang et al (2021). Thus, we fixed the source location at the center of landslide area for the following seismic analysis.…”

“…However, the system cannot provide timely information without the GeoPORT I. Thus, a direct way to improve the performance of current system is to deploy the temporal seismic arrays along highways for rock slopes with high-potential failure (Chang et al 2021). Most techniques used in the GeoPORT II are in situ, which may be limited in extreme weather conditions.…”

Life span of a landslide dam on mountain valley caught on seismic signals and its possible early warnings

“…Early identification of landslide dam formation is a challenge, but it is required for an emergency response. In the present study, we first utilized a flexible approach of seismic source scanning (GeoLoc scheme referred in Chang et al 2021) to detect seismic signals induced by landslides and locate its possible location. In the GeoLoc scheme, only stations with signal-to-noise ratios higher than 1.5 are used in the location processing.…”

“…A possible solution to overcome this monitoring difficulty is to adopt seismic techniques. Seismic signals have successfully been applied to study the landslide source dynamics (Allstadt 2013;Yamada et al 2013;Chao et al 2017;Chang et al 2021;Weng et al 2021), river sediment transport (Schmandt et al 2013;Chao et al 2015;Gimbert et al 2019), early identification of dam formation (Chao et al 2016), early warning of landslides (Poli 2017;Schöpa et al 2018), and debris flow mechanics (Walter et al 2017;Lai et al 2018). Deposit recent efforts in landslide seismology, we still lack a monitoring framework to completely trace the seismic signatures for detecting and locating the landslide, identifying the dam formation, and providing early warning for impending floods.…”

Rigidity Strengthening of Landslide Materials Measured by Seismic Interferometry

“…Landslide seismology has been applied within minutes after landslide occurrences to comprehensively understand the source parameters, such as event location [15,16], source dynamics [17][18][19], and magnitude [20,21]. However, how landslide seismology can be applied to slope failure prediction is another scientific concern.…”