Identifying rheological regimes within pyroclastic density currents

Jones, Thomas. J. and Shetty, Abhishek and Chalk, Caitlin and Dufek, Josef and Gonnermann, Helge M. (2024) Identifying rheological regimes within pyroclastic density currents. Nature Communications, 15 (1): 4401. ISSN 2041-1723

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Abstract

Pyroclastic density currents (PDCs) are the most lethal of all volcanic hazards. An ongoing challenge is to accurately forecast their run-out distance such that effective mitigation strategies can be implemented. Central to this goal is an understanding of the flow mobility—a quantitative rheological model detailing how the high temperature gas-pyroclast mixtures propagate. This is currently unknown, yet critical to accurately forecast the run-out distance. Here, we use a laboratory apparatus to perform rheological measurements on real gas-pyroclast mixtures at dynamic conditions found in concentrated to intermediate pumice-rich PDCs. We find their rheology to be non-Newtonian featuring (i) a yield stress where deposition occurs; (ii) shear-thinning behavior that promotes channel formation and local increases in velocity and (iii) shear-thickening behavior that promotes decoupling and potential co-PDC plume formation. We provide a universal regime diagram delineating these behaviors and illustrating how flow can transition between them during transport.

Item Type:
Journal Article
Journal or Publication Title:
Nature Communications
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1300
Subjects:
?? biochemistry, genetics and molecular biology(all)chemistry(all)physics and astronomy(all) ??
ID Code:
220655
Deposited By:
Deposited On:
28 May 2024 12:10
Refereed?:
Yes
Published?:
Published
Last Modified:
29 May 2024 02:35