Friction weakening in granular flows deduced from seismic records at the Soufrière Hills Volcano, Montserrat

Accurate modeling of rockfalls and pyroclastic flows is still an open issue, partly due to a lack of measurements related to their dynamics. Using seismic data from the Soufrière Hills Volcano, Montserrat, and granular flow modeling, we show that the power laws relating the seismic energy Es to the...

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Bibliographic Details
Published in:Journal of geophysical research. Solid earth 2015-11, Vol.120 (11), p.7536-7557
Main Authors: Levy, Clara, Mangeney, Anne, Bonilla, Fabian, Hibert, Clément, Calder, Eliza S., Smith, Patrick J.
Format: Article
Language:English
Subjects:
Coefficient of friction
Computer simulation
Constants
Correlation
Data conversion
Duration
Dynamics
Earth Sciences
Energy
Flow duration
Fractals
Friction
Friction weakening
Geophysics
granular flow
Grounds
Hills
Modelling
Plate tectonics
Potential energy
Power law
Rock falls
Sciences of the Universe
Seismic activity
Seismic data
Seismic energy
seismic records
Seismograms
Seismological data
Seismology
Soufrière Hills Volcano
Volcanoes
Volcanology
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Summary:Accurate modeling of rockfalls and pyroclastic flows is still an open issue, partly due to a lack of measurements related to their dynamics. Using seismic data from the Soufrière Hills Volcano, Montserrat, and granular flow modeling, we show that the power laws relating the seismic energy Es to the seismic duration ts and relating the loss of potential energy ΔEp to the flow duration tf are very similar, like the power laws observed at Piton de la Fournaise, Reunion Island. Observations showing that tf≃ts suggest a constant ratio Es/ΔEp≃10−5. This similarity in these two power laws can be obtained only when the granular flow model uses a friction coefficient that decreases with the volume transported. Furthermore, with this volume‐dependent friction coefficient, the simulated force applied by the flow to the ground correlates well with the seismic energy, highlighting the signature of this friction weakening effect in seismic data. Key Points The friction weakening of granular flows was evidenced using seismic data Conversion of potential to seismic energy is almost constant for granular flows Seismic energy correlates with the force applied by granular flows to the ground
ISSN:2169-9313
2169-9356
DOI:10.1002/2015JB012151