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A physical model of the high-frequency seismic signal generated by debris flows

Farin, Maxime and Tsai, Victor C. and Lamb, Michael P. and Allstadt, Kate E. (2019) A physical model of the high-frequency seismic signal generated by debris flows. Earth Surface Processes and Landforms, 44 (13). pp. 2529-2543. ISSN 0197-9337. https://resolver.caltech.edu/CaltechAUTHORS:20190604-151340833

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Abstract

We propose a physical model for the high‐frequency (>1 Hz) spectral distribution of seismic power generated by debris flows. The modeled debris flow is assumed to have four regions where the impact rate and impulses are controlled by different mechanisms: the flow body, a coarser‐grained snout, a snout lip where particles fall from the snout on the bed, and a dilute front composed of saltating particles. We calculate the seismic power produced by this impact model in two end‐member scenarios, a thin‐flow and thick‐flow limit, which assume that the ratio of grain sizes to flow thicknesses are either near unity or much less than unity. The thin‐flow limit is more appropriate for boulder‐rich flows that are most likely to generate large seismic signals. As a flow passes a seismic station, the rise phase of the seismic amplitude is generated primarily by the snout while the decay phase is generated first by the snout and then the main flow body. The lip and saltating front generate a negligible seismic signal. When ground properties are known, seismic power depends most strongly on both particle diameter and average flow speed cubed, and also depends on length and width of the flow. The effective particle diameter for producing seismic power is substantially higher than the median grain size and close to the 73rd percentile for a realistic grain size distribution. We discuss how the model can be used to estimate effective particle diameter and average flow speed from an integrated measure of seismic power.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/esp.4677DOIArticle
ORCID:
AuthorORCID
Farin, Maxime0000-0002-0250-2499
Tsai, Victor C.0000-0003-1809-6672
Lamb, Michael P.0000-0002-5701-0504
Allstadt, Kate E.0000-0003-4977-5248
Additional Information:© 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Received 20 November 2018; Revised 11 April 2019; Accepted 20 May 2019. We thank Dick Iverson for helpful comments on an early draft of the manuscript and we thank two anonymous reviewers for their comments. This work was supported by NSF grants EAR 1558479, EAR 1349115 and the Terrestrial Hazards Observation and Reporting Center at Caltech.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-1558479
NSFEAR-1349115
Caltech Terrestrial Hazard Observation and Reporting (THOR) CenterUNSPECIFIED
Issue or Number:13
Record Number:CaltechAUTHORS:20190604-151340833
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190604-151340833
Official Citation:Farin, M., Tsai, V. C., Lamb, M. P., and Allstadt, K. E. (2019) A physical model of the high‐frequency seismic signal generated by debris flows. Earth Surf. Process. Landforms, 44: 2529–2543. https://doi.org/10.1002/esp.4677
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96125
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Jun 2019 22:20
Last Modified:29 Oct 2019 17:09

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