An experimental study of volcanic tremor driven by magma wagging
department or school: Science, Faculty of
department or school: Earth, Ocean and Atmospheric Sciences, Department of
data provider: DSpace
degree campus: UBCV
creator: Dehghanniri, Vahid
issued: 2020-02-06T17:12:39Z
issued: 2020
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Pre-eruptive seismic tremor with similar spectral properties is observed at active volcanoes with widely ranging conduit geometries and structures. Accordingly, the ``magma wagging'' model introduced by Jellinek & Bercovici[21] and extended by Bercovici et al.[6] hypothesizes an underlying mechanism that is only weakly-sensitive to volcano architecture: Within active volcanic conduits, the flow of gas through a permeable foamy annulus of gas bubbles excites and maintains an oscillation of a central magma column through a well-known Bernoulli effect. In this thesis, we carry out a critical experimental test of this underlying mechanism for excitation. We explore the response of analog columns with prescribed elastic and linear damping properties to forced annular airflows. From high-speed video measurements of linear and orbital displacements and time series of accelerometer measurements we characterize and understand the excitation, evolution, and steady-state oscillating behaviors of analog magma columns over a broad range of conditions. We identify three distinct classes of wagging: i. rotational modes which confirms predictions for whirling modes by Liao et al.[26]; as well as newly-identified ii. mixed-mode; and iii. chaotic modes. We find that rotational modes are favored for symmetric, and high intensity forcing. Mixed-mode responses are favored for a symmetric and intermediate intensity forcing. Chaotic modes occur in asymmetric or low intensity forcing. To confirm and better understand our laboratory results, and also extend them to conditions beyond what is possible in the laboratory, we carry out complementary two-dimensional simulations of our analog experiments. Our combined experimental and numerical results can be applied to make qualitative predictions for natural testable in future studies of pre- and syn-eruptive volcano seismicity. Long before an eruptive phase, the total gas flux is low and we expect magma wagging in a chaotic mode, independent of…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/73486
note: An Experimental Study of Volcanic TremorDriven by Magma WaggingbyVahid DehghanniriBSc, University of Tehran, 2010MSc, K.N. Toosi University of Technology, 2013a thesis submitted in partial fulfillmentof the requirements for the degree ofMaster of Scienceinthe faculty of graduate and postdoctoralstudies(Geophysics)The University of British Columbia(Vancouver)January 2020c© Vahid Dehghanniri, 2020The following individuals certify that they have read, and recommend tothe Faculty of Graduate and Postdoctoral Studies for acceptance, the thesisentitled:An Experimental Study of Volcanic Tremor Driven by MagmaWaggingsubmitted by Vahid Dehghanniri in partial fulfillment of the requirementsfor the degree of Master of Science in Geophysics.Examining Committee:A. Mark JellinekSupervisorKelly RussellSupervisory Committee MemberValentina RadicSupervisory Committee MemberAli AmeliAdditional ExamineriiAbstractPre-eruptive seismic tremor with similar spectral properties is observed atactive volcanoes with widely ranging conduit geometries and structures. Ac-cordingly, the “magma wagging” model introduced by Jellinek & Bercovici[21]and extended by Bercovici et al.[6] hypothesizes an underlying mechanismthat is only weakly-sensitive to volcano architecture: Within active volcanicconduits, the flow of gas through a permeable foamy annulus of gas bubblesexcites and maintains an oscillation of a central magma column through awell-known Bernoulli effect. In this thesis, we carry out a critical exper-imental test of this underlying mechanism for excitation. We explore theresponse of analog columns with prescribed elastic and linear damping prop-erties to forced air annular airflows. From high speed video measurements oflinear and orbital displacements and time series of accelerometer measure-ments we characterize and understand the excitation, evolution, and steady-state oscillating behaviors of analog magma columns over a broad range ofconditions. We identify three distinct classes of wag…
has type: Thesis/Dissertation
date issued: 2020-05
is shown at: 10.14288/1.0388574
language: eng
degree discipline: Geophysics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/73486