4.18
Hdl Handle:
http://hdl.handle.net/10547/322902
Title:
Rock avalanches in high mountains
Authors:
Dunning, Stuart A.
Abstract:
Rock avalanches are a high magnitude, low frequency catastrophic mass movement involving the failure of over 1 x 106 m3 of mountainside. Rock avalanches are considered a major hazard of the high mountains due to the excessive run-out often associated with them. To date the mechanism that allows for such excessive travel distance is unproven although several dozen possibilities have been proposed. Rock-avalanche deposits exhibit characteristic features such as sharp lateral margins, confinement to local topography, super-elevation on valley sides, intensely fragmented interiors and preserved stratigraphy relative to the source. However, there are few detailed studies of the internal sedimentology of rock-avalanche deposits. Such studies are a vital piece of evidence in the search for the mechanisms of motion as rock avalanches are rarely witnessed. This thesis examines the detailed sedimentology of five rock avalanche deposits of varied lithology and morphology. A novel methodology is developed to sample deposits for their grainsize distributions (GSD). The GSD's prove similar for deposits, with significant variation due to preserved lithological banding in the interior. This finding refutes the commonly held view that rock-avalanche deposits are simply inversely graded. Instead, a facies model is developed of a coarse Carapace facies forming the surface and near surface that overlies a highly fragmented Body facies that is in turn underlain by the Basal facies that is free to interact with the substrate. The sedimentology of the Body facies is considered in fine detail and is shown to be fractal in nature, that is, self-similar at all scales of observation. A predictive sedimentological plot is presented that allows generation of the grain-size distribution and descriptive statistics from a simple estimation of weight percent gravel at a rock avalanche exposure. The morphology of rock-avalanche deposits are examined and a classification presented of 'spread' 'two-phase' and 'stalled'. The hazard and features of each morphology is described in relation to the observed deposits.
Citation:
Dunning, Stuart A. (2004) 'Rock avalanches in high mountains'. PhD thesis. University of Bedfordshire.
Publisher:
University of Bedfordshire
Issue Date:
Nov-2004
URI:
http://hdl.handle.net/10547/322902
Type:
Thesis or dissertation
Language:
en
Description:
A thesis submitted for the degree of Doctor of Philosophy of the University of Luton
Appears in Collections:
PhD e-theses

Full metadata record

DC FieldValue Language
dc.contributor.authorDunning, Stuart A.en
dc.date.accessioned2014-07-14T10:06:22Z-
dc.date.available2014-07-14T10:06:22Z-
dc.date.issued2004-11-
dc.identifier.citationDunning, Stuart A. (2004) 'Rock avalanches in high mountains'. PhD thesis. University of Bedfordshire.en
dc.identifier.urihttp://hdl.handle.net/10547/322902-
dc.descriptionA thesis submitted for the degree of Doctor of Philosophy of the University of Lutonen
dc.description.abstractRock avalanches are a high magnitude, low frequency catastrophic mass movement involving the failure of over 1 x 106 m3 of mountainside. Rock avalanches are considered a major hazard of the high mountains due to the excessive run-out often associated with them. To date the mechanism that allows for such excessive travel distance is unproven although several dozen possibilities have been proposed. Rock-avalanche deposits exhibit characteristic features such as sharp lateral margins, confinement to local topography, super-elevation on valley sides, intensely fragmented interiors and preserved stratigraphy relative to the source. However, there are few detailed studies of the internal sedimentology of rock-avalanche deposits. Such studies are a vital piece of evidence in the search for the mechanisms of motion as rock avalanches are rarely witnessed. This thesis examines the detailed sedimentology of five rock avalanche deposits of varied lithology and morphology. A novel methodology is developed to sample deposits for their grainsize distributions (GSD). The GSD's prove similar for deposits, with significant variation due to preserved lithological banding in the interior. This finding refutes the commonly held view that rock-avalanche deposits are simply inversely graded. Instead, a facies model is developed of a coarse Carapace facies forming the surface and near surface that overlies a highly fragmented Body facies that is in turn underlain by the Basal facies that is free to interact with the substrate. The sedimentology of the Body facies is considered in fine detail and is shown to be fractal in nature, that is, self-similar at all scales of observation. A predictive sedimentological plot is presented that allows generation of the grain-size distribution and descriptive statistics from a simple estimation of weight percent gravel at a rock avalanche exposure. The morphology of rock-avalanche deposits are examined and a classification presented of 'spread' 'two-phase' and 'stalled'. The hazard and features of each morphology is described in relation to the observed deposits.en
dc.language.isoenen
dc.publisherUniversity of Bedfordshireen
dc.subjectF643 Quaternary studiesen
dc.subjectavalanchesen
dc.subjectrock avalanchesen
dc.titleRock avalanches in high mountainsen
dc.typeThesis or dissertationen
dc.type.qualificationnamePhDen_GB
dc.type.qualificationlevelPhDen
dc.publisher.institutionUniversity of Bedfordshireen
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