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The 1998 debris avalanche at Casita volcano, Nicaragua - Investigation of the role of hydrothermal smectite in promoting slope instability.

Opfergelt, S., Delmelle, P., Boivin, P. and Delvaux, B. (2006) The 1998 debris avalanche at Casita volcano, Nicaragua - Investigation of the role of hydrothermal smectite in promoting slope instability. Geophysical Research Letters, 33 (15). ISSN 0094-8276

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Abstract

Buildup of excess pore water pressure within highly fractured rocks is held responsible for the initiation of the disastrous 1998 debris avalanche at Casita volcano, Nicaragua. Here, we postulate that the presence of smectite clay (up to 50 wt.%) in the hydrothermally-altered bedrock contributed to slope instability. Over decades or more, the clayey material probably (i) acted as an efficient barrier to water infiltration, (ii) progressively decreased shear-strength, and (iii) gradually destabilized the overlying rock mass. These effects are explained by the shrink-swell behavior of the clay-rich bedrock. During intense rainfall, formation of incipient weak failure surfaces in the superficial rock mass could have been favoured due to rapid alteration in the mechanical properties of smectite-containing clays deposited in fracture, joint and gouge interfaces.

Item Type: Article
Academic Units: The University of York > Environment (York)
Depositing User: York RAE Import
Date Deposited: 29 May 2009 09:13
Last Modified: 29 May 2009 09:13
Published Version: http://dx.doi.org/10.1029/2006GL026661
Status: Published
Publisher: American Geophysical Union
Identification Number: 10.1029/2006GL026661
URI: http://eprints.whiterose.ac.uk/id/eprint/6147

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