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A bedform phase diagram for dense granular currents

Smith, Gregory; Rowley, Peter; Williams, Rebecca; Giordano, Guido; Trolese, Matteo; Silleni, Aurora; Parsons, Daniel R.; Capon, Samuel

Authors

Gregory Smith

Peter Rowley

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Dr Rebecca Williams Rebecca.Williams@hull.ac.uk
Senior Lecturer; Associate Dean for Student Experience

Guido Giordano

Matteo Trolese

Aurora Silleni

Samuel Capon



Abstract

Pyroclastic density currents (PDCs) are a life-threatening volcanic hazard. Our understanding and hazard assessments of these flows rely on interpretations of their deposits. The occurrence of stratified layers, cross-stratification, and bedforms in these deposits has been assumed as indicative of dilute, turbulent, supercritical flows causing traction-dominated deposition. Here we show, through analogue experiments, that a variety of bedforms can be produced by denser, aerated, granular currents, including backset bedforms that are formed in waning flows by an upstream-propagating granular bore. We are able to, for the first time, define phase fields for the formation of bedforms in PDC deposits. We examine how our findings impact the understanding of bedform features in outcrop, using the example of the Pozzolane Rosse ignimbrite of the Colli Albani volcano, Italy, and thus highlight that interpretations of the formative mechanisms of these features observed in the field must be reconsidered.

Journal Article Type Article
Publication Date Dec 1, 2020
Journal Nature Communications
Electronic ISSN 2041-1723
Publisher Nature Publishing Group
Peer Reviewed Peer Reviewed
Volume 11
Issue 1
Article Number 2873
APA6 Citation Smith, G., Rowley, P., Williams, R., Giordano, G., Trolese, M., Silleni, A., …Capon, S. (2020). A bedform phase diagram for dense granular currents. Nature communications, 11(1), https://doi.org/10.1038/s41467-020-16657-z
DOI https://doi.org/10.1038/s41467-020-16657-z
Keywords Natural hazards; Sedimentology; Volcanology
Publisher URL https://www.nature.com/articles/s41467-020-16657-z#Abs1
Additional Information Received: 28 June 2019; Accepted: 12 May 2020; First Online: 8 June 2020; : The authors declare no competing interests.

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