Relations between the characteristics of granular column collapses and resultant high‐frequency seismic signals
Résumé
Deducing relations between the dynamic characteristics of landslides and rockfalls and the generated high-frequency (> 1 Hz) seismic signal is challenging. In order to get some insights into what relations could be tested in the field, we conduct laboratory experiments of granular column collapse on a rough inclined thin plate, for a large set of column masses, aspect ratios, particle diameters and slope angles. The dynamics of the granular flows is recorded using a high speed camera and the generated seismic signal is measured using piezoelectric accelerometers. Empirical scaling laws are established between the characteristics of the granular flows and deposits and that of the generated seismic signals. The radiated seismic energy scales with particle diameter as d 3 , column mass as M , aspect ratio as a 1.1 and initial column height as H 2 0. The increase of the radiated seismic energy as slope angle increases correlates with a similar increase in particle agitation. We interpret that the discrepancy of our empirical scaling laws with relations reported in the field can be explained by the complex influence of the substrate on seismic signal and the difference of flow initiation in both cases. However, our empirical scaling laws allow us to determine which flow parameters could be inferred from a given seismic characteristic in the field. In particular, by assuming the flow average speed is known, we show that we can retrieve parameters d, a and M within a factor of two from the seismic signal
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2019-Farin_et_al-2019-preprint-Journal_of_Geophysical_Research__Earth_Surface.pdf (5.88 Mo)
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