Seismic characterization of hyperconcentrated flows in a volcanic environment
Por:
Coviello, Velio, Capra, Lucia, Vazquez, Rosario, Marquez-Ramirez, Victor H.
Publicada:
1 ago 2018
Ahead of Print:
1 ene 2018
Resumen:
We present direct observations and monitoring data of a hyperconcentrated flow that occurred along La Lumbre ravine, one of the most active channels of Volcán de Colima in Mexico. Flow properties were inferred from video images and seismic data recorded by a geophone installed outside the channel. We collected flow samples 400 m upstream from the monitoring station and analyzed the variation of sediment concentration and grain-size distribution over time. A joint analysis of hydrological (i.e. flow velocity, wetted perimeter) and rheological (i.e. yield stress ty and dynamic viscosity µm) parameters was performed to characterize the flow. Different flow regimes and sediment transport processes were identified and analyzed in comparison with both the amplitude and spectral features of the seismic signal. We observed differing sediment concentrations at the same discharge, suggesting a decoupling between sediment transport processes and discharge for low-magnitude flows. A straightforward correlation was found between the amplitude of the seismic signal and the sediment concentration, and a value of 1.8 × 10-3 mm/s was identified that can be used as a threshold to recognize the hyperconcentrated phase of the flow. This information was tested on the complete seismic dataset gathered at La Lumbre ravine during the 2015 rainy season. We identified the transition from streamflow to hyperconcentrated flow (and/or vice versa) in 16 low-magnitude events and we validated this result using the video recordings. The correlation between seismic amplitude and sediment concentration is valid at La Lumbre ravine but would need to be tested in other locations for the development of automatic flow classification methods. This work contributes to standardized seismic methods for characterizing flow processes in volcanic environments, also for the development of lahar early warning systems. Copyright © 2018 John Wiley & Sons, Ltd. Copyright © 2018 John Wiley & Sons, Ltd.
Filiaciones:
Coviello, Velio:
Centro de Geociencias Universidad Nacional Autónoma de México Campus Juriquilla Querétaro México
Free University of Bozen-Bolzano Facoltà di Scienze e Tecnologie Bolzano Italy
Univ Nacl Autonoma Mexico, Ctr Geociencias, Campus Juriquilla, Queretaro, Mexico
Free Univ Bozen Bolzano, Fac Sci & Tecnol, Bolzano, Italy
Capra, Lucia:
Centro de Geociencias Universidad Nacional Autónoma de México Campus Juriquilla Querétaro México
Univ Nacl Autonoma Mexico, Ctr Geociencias, Campus Juriquilla, Queretaro, Mexico
Vazquez, Rosario:
Instituto de Geofísica Universidad Nacional Autónoma de México Unidad Michoacán Morelia México
Univ Nacl Autonoma Mexico, Inst Geofis, Unidad Michoacan, Morelia, Michoacan, Mexico
Marquez-Ramirez, Victor H.:
Centro de Geociencias Universidad Nacional Autónoma de México Campus Juriquilla Querétaro México
Univ Nacl Autonoma Mexico, Ctr Geociencias, Campus Juriquilla, Queretaro, Mexico
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