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Title: Computationally Modelling the Lava Dome at Soufriere Hills Volcano, Montserrat
Author: Hale, Alina Jane
Awarding Body: UNIVERSITY OF READING
Current Institution: University of Reading
Date of Award: 2005
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Abstract:
Finite element method (FEM) models using the commercially available software package FASTFLO and traditional low-level computational programming methods have been used to consider the Peleean lava dome extruded on Soufriere Hills Volcano, Montserrat. Phenomenological nonNewtonian models are used to describe the complex rheology of the lava and time-dependent processes. Four research areas are studied: endogenous dome growth, the transition from endogenous to exogenous dome growth, conduit flow dynamics and the stability of structures containing lava domes. An elasto-viscoplastic FEM model is used to analyse the rheological gradients and the growth and evolution of an endogenous lava dome. The transition from endogenous to exogenous dome growth is an important process in Peleean lava domes. It is found that the development of shear planes within the conduit and lava dome ultimately govern this process and that the lava must be non-Newtonian for shear planes to form. Temporal non-linearities observed in the extrusion rate for Soufriere Hills Volcano are analysed in conduit flow models. Accelerating extrusion rates can be explained by a change in magma chamber over-pressure and a 'rheological memory' associated with the magma. Non-Newtonian magma may form unstable shear planes due to gas over-pressure in the conduit and it is thought that this process is responsible for hybrid seismicity and oscillatory flow. Model results show a first order fit to the cyclicity behaviour observed. The graZritational instability of lava domes may be influenced by viscous relaxation. Instability models show a possible time-delayed collapse mechanism as well as enhanced front lobe toppling. Numerical models are only as useful as the data used to constrain them and due to a paucity of data these models should be regarded as qualitative rather than quantitative.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.485361  DOI: Not available
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