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Analogue models of the effect of long-term basement fault movement on volcanic edifices

Wooller, Luke; van Wyk de Vries, Benjamin; Cecchi, Emmanuelle and Rymer, Hazel (2009). Analogue models of the effect of long-term basement fault movement on volcanic edifices. Bulletin of Volcanology, 71(10) pp. 1111–1131.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1007/s00445-009-0289-3
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Abstract

Long-term fault movement under volcanoes can control the edifice structure and can generate collapse events. To study faulting effects, we explore a wide range of fault geometries and motions, from normal, through vertical to reverse and dip-slip to strike-slip, using simple analogue models. We explore the effect of cumulative sub-volcanic fault motions and find that there is a strong influence on the structural evolution and potential instability of volcanoes. The variety of fault types and geometries are tested with realistically scaled displacements, demonstrating a general tendency to produce regions of instability parallel to fault strike, whatever the fault motion. Where there is oblique-slip faulting, the instability is always on the downthrown side and usually in the volcano flank sector facing the strike-slip sense of motion. Different positions of the fault beneath the volcano change the location, type and magnitude of the instability produced. For example, the further the fault is from the central axis, the larger the destabilised sector. Also, with greater fault offset from the central axis larger unstable volumes are generated. Such failures are normal to fault strike. Using simple geometric dimensionless numbers, such as the fault dip, degree of oblique motion (angle of obliquity), and the fault position, we graphically display the geometry of structures produced. The models are applied to volcanoes with known underlying faults, and we demonstrate the importance of these faults in determining volcanic structures and slope instability. Using the knowledge of fault patterns gained from these experiments, geological mapping on volcanoes can locate fault influence and unstable zones, and hence monitoring of unstable flanks could be carried out to determine the actual response to faulting in specific cases.

Item Type: Journal Article
Copyright Holders: 2009 Springer-Verlag
ISSN: 0258-8900
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNER/S/A/2000/03505NERC (Natural Environment Research Council)
Not SetNot SetINSU PNRN (France)
Research Development Fund FellowshipNot SetOpen University
Keywords: volcano-tectonics; fault; analogue modelling; lateral collapse; debris avalanche; deformation
Academic Unit/Department: Science
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 18513
Depositing User: Hazel Rymer
Date Deposited: 01 Oct 2009 15:47
Last Modified: 21 Mar 2014 12:40
URI: http://oro.open.ac.uk/id/eprint/18513
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