Characterization of rockfalls from seismic signal: Insights from laboratory experiments

Farin, Maxime; Mangeney, Anne; Toussaint, Renaud; Rosny, Julien de; Shapiro, N. M.; Dewez, Thomas; Hibert, Clément; Mathon, Christian; Sedan, Olivier; Berger, Frédéric

doi:10.1002/2015jb012331

Cited by 48 publications

(125 citation statements)

References 56 publications

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“…Recent studies (e.g. Helmstetter and Garambois, 2010;Hibert et al, 2011;Burtin et al, 2014;Farin et al, 2015) have focused on monitoring activity at catchment or sub-catchment scale, usually either with limited validation against independent data, focusing on detachment volumes above 10 3 m 3 , or working under very controlled, laboratory-like experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

Seismic monitoring of small alpine rockfalls – validity, precision and limitations

Dietze

Mohadjer²,

Turowski

et al. 2017

Earth Surf. Dynam.

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Abstract. Rockfall in deglaciated mountain valleys is perhaps the most important post-glacial geomorphic process for determining the rates and patterns of valley wall erosion. Furthermore, rockfall poses a significant hazard to inhabitants and motivates monitoring efforts in populated areas. Traditional rockfall detection methods, such as aerial photography and terrestrial laser scanning (TLS) data evaluation, provide constraints on the location and released volume of rock but have limitations due to significant time lags or integration times between surveys, and deliver limited information on rockfall triggering mechanisms and the dynamics of individual events. Environmental seismology, the study of seismic signals emitted by processes at the Earth's surface, provides a complementary solution to these shortcomings. However, this approach is predominantly limited by the strength of the signals emitted by a source and their transformation and attenuation towards receivers. To test the ability of seismic methods to identify and locate small rockfalls, and to characterise their dynamics, we surveyed a 2.16 km 2 large, near-vertical cliff section of the Lauterbrunnen Valley in the Swiss Alps with a TLS device and six broadband seismometers. During 37 days in autumn 2014, 10 TLS-detected rockfalls with volumes ranging from 0.053 ± 0.004 to 2.338 ± 0.085 m 3 were independently detected and located by the seismic approach, with a deviation of 81 +59 −29 m (about 7 % of the average inter-station distance of the seismometer network). Further potential rockfalls were detected outside the TLS-surveyed cliff area. The onset of individual events can be determined within a few milliseconds, and their dynamics can be resolved into distinct phases, such as detachment, free fall, intermittent impact, fragmentation, arrival at the talus slope and subsequent slope activity. The small rockfall volumes in this area require significant supervision during data processing: 2175 initially picked potential events reduced to 511 potential events after applying automatic rejection criteria. The 511 events needed to be inspected manually to reveal 19 short earthquakes and 37 potential rockfalls, including the 10 TLS-detected events. Rockfall volume does not show a relationship with released seismic energy or peak amplitude at this spatial scale due to the dominance of other, process-inherent factors, such as fall height, degree of fragmentation, and subsequent talus slope activity. The combination of TLS and environmental seismology provides, despite the significant amount of manual data processing, a detailed validation of seismic detection of small volume rockfalls, and revealed unprecedented temporal, spatial and geometric details about rockfalls in steep mountainous terrain.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Introductionmentioning

confidence: 99%

Seismic monitoring of small alpine rockfalls – validity, precision and limitations

Dietze

Mohadjer²,

Turowski

et al. 2017

Earth Surf. Dynam.

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“…The analysis based on Hertz's theory of impact conducted by Farin et al (2015) yielded the parameter mV 13/5 z , with m the mass of the block and V z the vertical velocity before impact, which should in theory scale with the radiated seismic energy E s of the seismic signal generated at each impact. However, when investigating this relationship for real single-block rockfalls, they did not found a significant correlation with this parameter.…”

Section: Correlation Between Dynamic Parameters and Seismic Signal Fementioning

confidence: 99%

“…Theoretical developments as well as laboratory and field experiments were conducted by Farin et al (2015) to address this issue. These authors have shown that the mass and the speed of an impactor can be related to the radiated elastic energy and to the spectrum of the signal, following analytic developments based on the Hertz theory of impact (Hertz, 1882).…”

Section: As Well As Theirmentioning

confidence: 99%

Single-block rockfall dynamics inferred from seismic signal analysis

et al. 2017

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Abstract. Seismic monitoring of mass movements can significantly help to mitigate the associated hazards; however, the link between event dynamics and the seismic signals generated is not completely understood. To better understand these relationships, we conducted controlled releases of single blocks within a soft-rock (black marls) gully of the Rioux-Bourdoux torrent (French Alps). A total of 28 blocks, with masses ranging from 76 to 472 kg, were used for the experiment. An instrumentation combining video cameras and seismometers was deployed along the travelled path. The video cameras allow reconstructing the trajectories of the blocks and estimating their velocities at the time of the different impacts with the slope. These data are compared to the recorded seismic signals. As the distance between the falling block and the seismic sensors at the time of each impact is known, we were able to determine the associated seismic signal amplitude corrected for propagation and attenuation effects. We compared the velocity, the potential energy lost, the kinetic energy and the momentum of the block at each impact to the true amplitude and the radiated seismic energy. Our results suggest that the amplitude of the seismic signal is correlated to the momentum of the block at the impact. We also found relationships between the potential energy lost, the kinetic energy and the seismic energy radiated by the impacts. Thanks to these relationships, we were able to retrieve the mass and the velocity before impact of each block directly from the seismic signal. Despite high uncertainties, the values found are close to the true values of the masses and the velocities of the blocks. These relationships allow for gaining a better understanding of the physical processes that control the source of high-frequency seismic signals generated by rockfalls.

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“…Most of these location approaches were formulated in a script 30 language and can thus in principle be translated to R to become a valuable part, increasing the applicability and flexibility of the package. Physically based or empirical scaling models for other than fluid turbulence become more and more available (e.g., Tsai et al, 2012;Farin et al, 2015) and will allow tackling innovative research questions, especially when combined with Rprovided methods to account for the inherent uncertainty of the model parameters, way beyond the simple example from section 4.2. Integrating such models to the 'eseis' package is a step that has already been started and that will continue.…”

Section: Anticipated Future Functionalitiesmentioning

confidence: 99%

The R package eseis – a comprehensive software toolbox for environmental seismology

Dietze

2018

Preprint

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Abstract. Environmental seismology is the study of the seismic signals emitted by Earth surface processes. This emerging research field is at the seams of seismology, geomorphology, hydrology, meteorology, and further Earth science disciplines.It amalgamates a wide variety of methods from across these disciplines and, ultimately, fuses them in a common analysis environment. This overarching scope of environmental seismology asks for a coherent, yet integrative software, which is accepted by many of the involved scientific disciplines. The statistic software R has gained paramount importance in the 5 majority of data science research fields. R has well justified advances over other, mostly commercial software, which makes it the ideal language to base a comprehensive analysis toolbox on. The article introduces the avenues and needs of environmental seismology, and how these are met by the R package 'eseis'. The conceptual structure, example data sets and available functions are demonstrated. Worked examples illustrate possible applications of the package and in depth descriptions of the flexible use of the functions. The package is available under the GPL license on the Comprehensive R Archive Network (CRAN) and 10 maintained on Github.

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Characterization of rockfalls from seismic signal: Insights from laboratory experiments

Cited by 48 publications

References 56 publications

Seismic monitoring of small alpine rockfalls – validity, precision and limitations

Seismic monitoring of small alpine rockfalls – validity, precision and limitations

Single-block rockfall dynamics inferred from seismic signal analysis

The R package eseis – a comprehensive software toolbox for environmental seismology

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