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Experimental observations of pressure oscillations and flow regimes in an analogue volcanic system.

Lane, Steve J. and Chouet, Bernard A. and Phillips, Jeremy C. and Dawson, Philip and Ryan, Graham A. and Hurst, Emma (2001) Experimental observations of pressure oscillations and flow regimes in an analogue volcanic system. Journal of Geophysical Research: Solid Earth, 106 (B4). pp. 6461-6476. ISSN 2196-9356

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    Abstract

    Gas-liquid flows, designed to be analogous to those in volcanic conduits, are generated in the laboratory using organic gas-gum rosin mixtures expanding in a vertically mounted tube. The expanding fluid shows a range of both flow and pressure oscillation behaviors. Weakly supersaturated source liquids produce a low Reynolds number flow with foam expanding from the top surface of a liquid that exhibits zero fluid velocity at the tube wall; i.e., the conventional “no-slip” boundary condition. Pressure oscillations, often with strong long-period characteristics and consistent with longitudinal and radial resonant oscillation modes, are detected in these fluids. Strongly supersaturated source liquids generate more energetic flows that display a number of flow regimes. These regimes include a static liquid source, viscous flow, detached flow (comprising gas-pockets-at-wall and foam-in-gas annular flow, therefore demonstrating strong radial heterogeneity), and a fully turbulent transonic fragmented or mist flow. Each of these flow regimes displays characteristic pressure oscillations that can be related to resonance of flow features or wall impact phenomena. The pressure oscillations are produced by the degassing processes without the need of elastic coupling to the confining medium or flow restrictors and valvelike features. The oscillatory behavior of the experimental flows is compared to seismoacoustic data from a range of volcanoes where resonant oscillation of the fluid within the conduit is also often invoked as controlling the observed oscillation frequencies. On the basis of the experimental data we postulate on the nature of seismic signals that may be measured during large-scale explosive activity.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research: Solid Earth
    Additional Information: Copyright (2001) American Geophysical Union.
    Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
    Departments: Faculty of Science and Technology > Lancaster Environment Centre
    ID Code: 923
    Deposited By: Dr Steve Lane
    Deposited On: 09 Sep 2008 16:11
    Refereed?: Yes
    Published?: Published
    Last Modified: 17 Sep 2013 08:24
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/923

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