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Laboratory landquakes: Insights from experiments into the high-frequency seismic signal generated by geophysical granular flows
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  • Matthew Iain Arran,
  • Anne Mangeney,
  • Julien de Rosny,
  • Maxime Farin,
  • Renaud Toussaint,
  • Olivier Roche
Matthew Iain Arran
Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France, Institut de Physique du Globe de Paris

Corresponding Author:[email protected]

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Anne Mangeney
Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France, Institut de Physique du Globe de Paris
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Julien de Rosny
Laboratoire Ondes et Acoustique, Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005 Paris, France, Laboratoire Ondes et Acoustique
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Maxime Farin
Laboratoire Ondes et Acoustique, Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005 Paris, France, Institut Langevin
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Renaud Toussaint
Université de Strasbourg, CNRS, Institut Terre et Environnement de Strasbourg, UMR 7063, F-67084 Strasbourg, France, Institut de Physique du Globe de Strasbourg
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Olivier Roche
Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, F-63000 Clermont-Ferrand, France, Laboratoire Magmas et Volcans (Université Clermont Auvergne-CNRS-IRD)
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Abstract

Geophysical granular flows exert basal forces that generate seismic signals, which can be used to better monitor and model these severe natural hazards. A number of empirical relations and existing models link these signals’ high-frequency components to a variety of flow properties, many of which are inaccessible by other analyses. However, the range of validity of the empirical relations remains unclear and the models lack validation, owing to the difficulty of adequately controlling and instrumenting field-scale flows. Here, we present laboratory experiments investigating the normal forces exerted on a basal plate by dense and partially dense flows of spherical glass particles. We measured the power spectra of these forces and inferred predictions for these power spectra from the models for debris flows’ seismic signals proposed by Kean et al. (2015), Lai et al. (2018), and Farin, Tsai, et al. (2019), using Hertz theory to extend Farin, Tsai, et al. (2019)’s models to higher frequencies. Comparison of our bservations to these predictions, and to predictions derived from Bachelet (2018) and Bachelet et al. (2021)’s model for granular flows’ seismic signals, shows those of Farin, Tsai, et al. (2019)’s ‘thin-flow’ model to be the most accurate, so we examine explanations for this accuracy and discuss its implications for geophysical flows’ seismic signals. We also consider the normalisation, by the mean force exerted by each flow, of the force’s mean squared fluctuations, showing that this ratio varies by four orders of magnitude over our experiments, but is determined by the bulk inertial number of the flow.
May 2021Published in Journal of Geophysical Research: Earth Surface volume 126 issue 5. 10.1029/2021JF006172