Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio

Abstract The aspect ratio of ignimbrites is a commonly used parameter that has been related to the energy of the parent pyroclastic density currents (PDCs). However this parameter, calculated as the ratio between the average thickness and the average lateral extent of ignimbrites, does not capture f...

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Autores principales:	Guido Giordano, Domenico M. Doronzo
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/21ac043630144345a6b0e6503429042f
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spelling	oai:doaj.org-article:21ac043630144345a6b0e6503429042f2021-12-02T15:06:17ZSedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio10.1038/s41598-017-04880-62045-2322https://doaj.org/article/21ac043630144345a6b0e6503429042f2017-06-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-04880-6https://doaj.org/toc/2045-2322Abstract The aspect ratio of ignimbrites is a commonly used parameter that has been related to the energy of the parent pyroclastic density currents (PDCs). However this parameter, calculated as the ratio between the average thickness and the average lateral extent of ignimbrites, does not capture fundamental differences in pyroclastic flow mobility nor relates to lithofacies variations of the final deposits. We herein introduce the “topological aspect ratio” (ARt) as the ratio of the local deposit thickness (Ht) to the distance between the local site and the maximum runout distance (Lt), where Ht is a proxy for the PDC tendency to deposit, and Lt a proxy for the PDC mobility or its tendency to further transport the pyroclastic material. The positive versus negative spatial gradient d(ARt)/dx along flow paths discriminate zones where PDCs are forced (i.e. where they transport the total energy under the action of mass discharge rate) from zones where they are inertial (i.e. where they transport the total energy under the action of viscous or turbulent fluidization). Though simple to apply, the topological aspect ratio and its spatial gradient are powerful descriptors of the interplay between sedimentation and mobility of PDCs, and of the resulting lithofacies variations.Guido GiordanoDomenico M. DoronzoNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-7 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Guido Giordano Domenico M. Doronzo Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio
description	Abstract The aspect ratio of ignimbrites is a commonly used parameter that has been related to the energy of the parent pyroclastic density currents (PDCs). However this parameter, calculated as the ratio between the average thickness and the average lateral extent of ignimbrites, does not capture fundamental differences in pyroclastic flow mobility nor relates to lithofacies variations of the final deposits. We herein introduce the “topological aspect ratio” (ARt) as the ratio of the local deposit thickness (Ht) to the distance between the local site and the maximum runout distance (Lt), where Ht is a proxy for the PDC tendency to deposit, and Lt a proxy for the PDC mobility or its tendency to further transport the pyroclastic material. The positive versus negative spatial gradient d(ARt)/dx along flow paths discriminate zones where PDCs are forced (i.e. where they transport the total energy under the action of mass discharge rate) from zones where they are inertial (i.e. where they transport the total energy under the action of viscous or turbulent fluidization). Though simple to apply, the topological aspect ratio and its spatial gradient are powerful descriptors of the interplay between sedimentation and mobility of PDCs, and of the resulting lithofacies variations.
format	article
author	Guido Giordano Domenico M. Doronzo
author_facet	Guido Giordano Domenico M. Doronzo
author_sort	Guido Giordano
title	Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio
title_short	Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio
title_full	Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio
title_fullStr	Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio
title_full_unstemmed	Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio
title_sort	sedimentation and mobility of pdcs: a reappraisal of ignimbrites’ aspect ratio
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/21ac043630144345a6b0e6503429042f
work_keys_str_mv	AT guidogiordano sedimentationandmobilityofpdcsareappraisalofignimbritesaspectratio AT domenicomdoronzo sedimentationandmobilityofpdcsareappraisalofignimbritesaspectratio
_version_	1718388499865927680

Sedimentation and mobility of PDCs: a reappraisal of ignimbrites’ aspect ratio

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