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Preprints
https://doi.org/10.5194/egusphere-2023-2695
https://doi.org/10.5194/egusphere-2023-2695
08 Dec 2023
 | 08 Dec 2023

Exploratory analysis of the annual risk to life from debris flows

Mark Bloomberg, Tim Davies, Elena Moltchanova, Tom Robinson, and David Palmer

Abstract. Debris flows are hazardous yet often unrecognised and poorly understood by the public and natural hazards community. Some catchments generate debris flows with average recurrence intervals (ARIs) <10 years, but most debris flow catchments have ARIs ranging from decades to millennia. Consequently, many debris flow catchments pose an underappreciated hazard, especially where there are dwellings on debris flow fans and other depositional areas.

Here, we describe how to use simple and well-accepted methods to:

  • Make a preliminary identification of catchments that are susceptible to debris flows.
  • Estimate the threshold ARI for debris flows in a catchment below which there is an unacceptable annual risk to life for the occupiers of any dwellings.
  • Identify the "window of non-recognition" where debris flows are sufficiently infrequent within a catchment that it is not recognised as susceptible, yet frequent enough that the risk to life exceeds the accepted threshold.
  • Explore the influence of the important parameters driving the annual risk to life from debris flows.

We show that, given precautionary but realistic assumptions about debris flow hazards and the vulnerability of dwellings and their occupants, catchments with no history of debris flow activity can pose an unrecognised and unacceptable risk to life.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

11 Feb 2025
Identifying unrecognised risks to life from debris flows
Mark Bloomberg, Tim Davies, Elena Moltchanova, Tom Robinson, and David Palmer
Nat. Hazards Earth Syst. Sci., 25, 647–656, https://doi.org/10.5194/nhess-25-647-2025,https://doi.org/10.5194/nhess-25-647-2025, 2025
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Debris flows occur infrequently, with average recurrence intervals (ARIs) ranging from decades...
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