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Published April 2021 | public
Journal Article

The mysterious grooves of Volcán Bárcena: a review of the role of streamwise counter-rotating vortices during erosion by dilute pyroclastic density currents


Although erosion during high-energy passage of a pyroclastic density current (PDC) causes great damage, analyses of the effects of such erosion are sparse in scientific literature compared to observations and interpretations of depositional processes. In this paper, we review observations of surfaces where PDCs have eroded sets of grooves that provide information on the erosion process. We postulate that in some cases, the grooves were carved by streamwise vortices in the boundary layer of the PDC and review possible fluid dynamic instabilities that can give rise to such vortices. For the prominent grooves at Volcán Bárcena, Mexico, we propose that a fluid dynamic instability, which we dub the "groovy instability," occurred and caused formation of erosive counter-rotating vortices. This instability occurs when the particle concentration boundary layer thickness, δ_c, is larger than the velocity (shear) boundary layer thickness, δ_u, i.e., L=δ_c /δ_u>1. In subaqueous turbidity currents, these vortices have a typical wavelength of ~25*δ_c. If this relation is applied to the grooves formed on Volcán Bárcena, the inferred particle concentration boundary layer is estimated to have been <1 m thick. We postulate that a transition between erosion of grooves and deposition of dunes at Volcán Bárcena occurred when hydraulically supercritical flow on the upper flanks changed to subcritical flow about halfway down the mountain. We call attention to boundary layer dynamics in erosive pyroclastic density currents at a dimension that is difficult to scale quantitatively in laboratory experiments and is usually not resolved computationally and to the need for incorporating such dynamics into models of PDC dynamics.

Additional Information

© International Association of Volcanology & Chemistry of the Earth's Interior 2021. Received 30 January 2020; Accepted 28 January 2021; Published 27 March 2021. We thank Jim Moore of the US Geological Survey for providing Richards' original photos, Tom Pierson of the US Geological Survey for the Ruiz observations and photos, and Steve Sparks and Simon Powell of Bristol University for the images of Lascar and Soufrière Hills. We also thank Michael Ort for handling the reviews and for his own review comments, Frances van Wyk de Vries for the help with submission logistics, Andrew Harris for the encouragement to write this review article, and Roberto Sulpizio and an anonymous reviewer for the very detailed and helpful comments that greatly improved our analysis of the grooves on Volcán Bárcena. Code availability: Not applicable. Funding: SWK gratefully acknowledges support from the Charles R. Walgreen, Jr. Foundation. EM gratefully acknowledges support from the National Science Foundation under grant CBET-1803380 and from the Army Research Office under grant W911NF-18-1-0379. JB acknowledges support from the Jack and Richard Threet chair in Sedimentary Geology. JMA thanks the Foster and Coco Stanback Innovation Fund for their support of this collaboration. Author Contributions: SWK, EM, and JB were involved in all aspects of the work. JA was involved in the supercritical flow/hydraulic jump theory. The authors declare no competing interests.


Kieffer, S.W., Meiburg, E., Best, J. et al. Correction to: The mysterious grooves of Volcán Bárcena: a review of the role of streamwise counter-rotating vortices during erosion by dilute pyroclastic density currents. Bull Volcanol 83, 32 (2021). https://doi.org/10.1007/s00445-021-01456-1

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August 22, 2023
October 23, 2023