Locating, monitoring, and characterizing typhoon-linduced landslides with real-time seismic signals

Kao, Honn; Kan, Chih-Wen; Chen, Rong-Yuh; Chang, C. C.; Rosenberger, A.; Shin, Tzay‐Chyn; Leu, Pei-Ling; Kuo, Kai-Wen; Liang, Wen‐Tzong

doi:10.1007/s10346-012-0322-z

Cited by 35 publications

(27 citation statements)

References 17 publications

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“…In their studies, Surinach et al (2005) and Dammeier et al (2011) reported that rockfall spectrograms show a typical triangular shape that could be related to source effects, material entrainment during propagation and/or progressive failure and individual block impacts (Norris, 1994;McSaveney and Downes, 2002). All these characteristics can be used for event detection at different scales (Helmstetter and Garambois, 2010;Yamada et al, 2012;Kao et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Seismic and mechanical studies of the artificially triggered rockfall at Mount Néron (French Alps, December 2011)

Bottelin

Jongmans

Daudon

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. The eastern limestone cliff of Mount Néron (French Alps) was the theater for two medium-size rockfalls between summer and winter 2011. On 14 August 2011, a ∼ 2000 m 3 rock compartment detached from the cliff, fell 100 m below and propagated down the slope. Although most of the fallen rocks deposited on the upper part of the slope, some blocks of about 15 m in size were stopped by a ditch and an earthen barrier after a run-out of 800 m. An unstable overhanging ∼ 2600 m 3 compartment remained attached to the cliff and was blasted on 13 December 2011. During this artificially triggered event, 7 blocks reached the same ditch, with volumes ranging from 0.8 to 12 m 3 . A semi-permanent seismic array located about 2.5 km from the site recorded the two events, providing a unique opportunity to understand and to compare the seismic phases generated during natural and artificially triggered rockfalls. Both events have signal duration of ∼ 100 s with comparable maximum amplitudes recorded at large distances (computed local magnitude of 1.14 and 1.05, respectively), most of the energy lying below 20 Hz. Remote sensing techniques (photogrammetry and lidar) were employed before and after the provoked rockfall, allowing the volume and fracturing to be characterized. This event was filmed by two video cameras, and the generated ground motions were recorded using two temporary 3C seismic sensors and three seismic arrays deployed at the slope toe.Videos and seismogram processing provided estimates of the propagation velocity during the successive rockfall phases, which ranges from 12 to 30 m s −1 . The main seismic phases were obtained from combined video and seismic signal analyses. The two most energetic phases are related to the ground impact of fallen material after free fall, and to individual rock block impacts into the ditch and the earthen barrier. These two phases are characterized by similar lowfrequency content but show very different particle motions. The discrete element technique allowed reproducing the key features of the rockfall dynamics, yielding propagation velocities compatible with experimental observations.

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Section: Introductionmentioning

confidence: 99%

Seismic and mechanical studies of the artificially triggered rockfall at Mount Néron (French Alps, December 2011)

Bottelin

Jongmans

Daudon

et al. 2014

Nat. Hazards Earth Syst. Sci.

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“…However, it should be kept in mind that larger mass wasting events can have a distinct long‐period signal, 10–30 s, that may be recorded at great distance [ Lin et al ., ; Ekström and Stark , ]. Smaller landslides produce seismic signals that last several minutes, sometimes up to tens of minutes, with high amplitudes, irregular envelopes, and a lack of distinctive arrivals of P and S seismic phases [ La Rocca et al ., ; Suriñach et al ., ; Favreau et al ., ; Kao et al ., ]. The seismic energy is dominant in the 0.1–10 Hz frequency band but long‐period waves can be recorded [ Favreau et al ., ].…”

Section: Seismological Methodsmentioning

confidence: 99%

“…We then applied a 1 s smoothing window to the amplitude functions. This corresponds to the weighting factor W m in Kao et al [2012], fixed at a value of 1. For a set of smoothed amplitude functions, we then calculated the signal to noise ratio (SNR) in order to determine the quality of the seismic data before migration.…”

Section: Amplitude Functionmentioning

confidence: 99%

Continuous catchment‐scale monitoring of geomorphic processes with a 2‐D seismological array

et al. 2013

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[1] Distributed activity of geomorphic processes with different spatiotemporal scales is hard to monitor in detail with conventional methods but might be detected with seismometers. From July to September 2010, we deployed 14 seismometers to evaluate the ability of a two-dimensional array with small interstation distances (11 km) to continuously monitor geomorphic processes in a mountain catchment (370 km 2 ) in Taiwan. Spectral analysis of seismic records highlights different sources with high-frequency content (>1 Hz), consistent with hillslope and river processes. Using a common detection algorithm and a location technique based on the timing of seismic amplitude, we have located 314 near-surface events, most of which (69%) occurred during daily convective storms. Event activity was positively correlated with the precipitation intensity, but this relation was not uniform in the catchment. High-resolution satellite images and air photos did not show geomorphic change during the study, which did not have any episodes of extreme precipitation. A majority of events (61%) were collocated with preexisting geomorphic features (landslide scars, gullies) within the uncertainty on location (9% of interstation distance). The combination of event location and timing suggests a geomorphic source of recorded signals and most events had the seismic characteristics of rockfall, debris avalanches, or slides. Reactivation of prior erosion sites by such processes is difficult to detect with imagery, but can possibly be resolved by seismic monitoring. When proven, this approach will allow a spatially comprehensive survey of geomorphic activity at the catchment scale, with temporal detail sufficient to evaluate the exact (meteorological) conditions under which process events occur.

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“…The SSA was originally designed to locate non‐volcanic tremors with emergent arrivals (Kao & Shan 2004). Recent development of the SSA has expanded its application to other seismological problems such as the rapid identification of fault planes for earthquakes (Kao & Shan 2007; Kao et al 2008), delineation of source characteristics of earthquake doublets (Kan et al 2010) and near‐real‐time epicentral determination of landslides (Kao et al 2012).…”

Section: Methodsmentioning

confidence: 99%

Delineating complex spatiotemporal distribution of earthquake aftershocks: an improved Source-Scanning Algorithm

Liao

Kao

Rosenberger

et al. 2012

Geophysical Journal International

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SUMMARY Conventional earthquake location methods depend critically on the correct identification of seismic phases and their arrival times from seismograms. Accurate phase picking is particularly difficult for aftershocks that occur closely in time and space, mostly because of the ambiguity of correlating the same phase at different stations. In this study, we introduce an improved Source‐Scanning Algorithm (ISSA) for the purpose of delineating the complex distribution of aftershocks without time‐consuming and labour‐intensive phase‐picking procedures. The improvements include the application of a ground motion analyser to separate P and S waves, the automatic adjustment of time windows for ‘brightness’ calculation based on the scanning resolution and a modified brightness function to combine constraints from multiple phases. Synthetic experiments simulating a challenging scenario are conducted to demonstrate the robustness of the ISSA. The method is applied to a field data set selected from the ocean‐bottom‐seismograph records of an offshore aftershock sequence southwest of Taiwan. Although visual inspection of the seismograms is ambiguous, our ISSA analysis clearly delineates two events that can best explain the observed waveform pattern.

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Locating, monitoring, and characterizing typhoon-linduced landslides with real-time seismic signals

Cited by 35 publications

References 17 publications

Seismic and mechanical studies of the artificially triggered rockfall at Mount Néron (French Alps, December 2011)

Seismic and mechanical studies of the artificially triggered rockfall at Mount Néron (French Alps, December 2011)

Continuous catchment‐scale monitoring of geomorphic processes with a 2‐D seismological array

Delineating complex spatiotemporal distribution of earthquake aftershocks: an improved Source-Scanning Algorithm

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