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Estimating rates of debris flow entrainment from ground vibrations
Author(s) -
Kean J. W.,
Coe J. A.,
Coviello V.,
Smith J. B.,
McCoy S. W.,
Arattano M.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064811
Subject(s) - entrainment (biomusicology) , geology , debris flow , debris , sediment , fluvial , magnitude (astronomy) , sediment transport , channel (broadcasting) , flow (mathematics) , geomorphology , geotechnical engineering , mechanics , physics , oceanography , engineering , structural basin , astronomy , rhythm , acoustics , electrical engineering
Debris flows generate seismic waves as they travel downslope and can become more dangerous as they entrain sediment along their path. We present field observations that show a systematic relation between the magnitude of seismic waves and the amount of erodible sediment beneath the flow. Specifically, we observe that a debris flow traveling along a channel filled initially with sediment 0.34 m thick generates about 2 orders of magnitude less spectral power than a similar‐sized flow over the same channel without sediment fill. We adapt a model from fluvial seismology to explain this observation and then invert it to estimate the level of bed sediment (and rate of entrainment) beneath a passing series of surges. Our estimates compare favorably with previous direct measurements of entrainment rates at the site, suggesting the approach may be a new indirect way to obtain rare field constraints needed to test models of debris flow entrainment.