title: Understanding emplacement of rapidly-emplaced volume-limited lava flows
      from Mount Etna’s 2011-2012 eruption
title: a multidisciplinary study
titleType: Subtitle
Creators: name: Hancock, Anson
Publisher: name: Lancaster University
Year: 2018
Subjects: Volcanology
Lava flow emplacement
Remote sensing
thermal camera images
Time-lapse imaging

description: While the study of emplacement in most literature focuses on long-duration
      cooling-limited lava flows, the short duration and rapid emplacement of
      many volume-limited flows impedes their analysis. This thesis aims to
      improve understanding of the emplacement of shortduration volume-limited
      lava flows by: (1) employing long-range ground-based visible timelapse
      data and thermo-rheological modelling to understand and analyze the
      importance of different factors which influence lava flow emplacement, and
      (2) developing a workflow for improving the application of long-range
      ground-based thermal cameras for studying lava flows.
      
      Results from (1) agreed with previous studies, showing strong correlations
      between final flow length and the following: total volume, duration, flow
      field width, number of bifurcations in the proximal zone of the flow,
      number of confluences, average and maximum advance rate in the proximal
      zone, and duration of fire fountaining. However, unlike previous studies,
      no correlation was found between final flow length and mean output rate.
      Visual analysis identified two flow groups based on morphology within the
      proximal zone of the flow, and results indicated that differences in
      advance rates and at-vent initial effusion rates dictated the morphology
      observed for the two groups. Analysing flow confinement indicated a strong
      relationship between final length and the distance of confinement of the
      primary flow. Utilising multiple regression analysis, maximum flow width,
      duration of flow, and maximum advance rate in the proximal zone produced
      the best model for flow length in terms of explanatory and predictive
      power.
      
      By substituting flow widths estimated from the time-lapse data for channel
      widths, FLOWGOmodelled effusion rates and total volumes were obtained for
      the primary flows of the 12 May and 19 July 2011 episodes at Mt. Etna
      which were within the range of values estimated by previous studies.
      Additionally, using FLOWGO to model flow thickness changes due to
      bifurcations of the primary flow produced average flow thickness estimates
      for the semichannelized 12 May flow that agreed with estimates from
      previous studies. However, no thickness estimates were possible using this
      method for the unconfined 19 July flow. This suggests that substituting
      flow width for channel width in FLOWGO for unconfined flows is
      inappropriate and should only be applied to flows with a more channel-like
      morphology.
      
      A workflow was developed to achieve objective (2) and applied to the 29
      August 2011 episode at Mt. Etna to correct ground-based thermal data for
      atmospheric and viewing effects due to long viewing paths along two
      different viewing geometries (horizontal- and slant-path). Estimates of
      flow area, volume, and mean output rate using both viewing geometries were
      within the range of values reported in the literature. Estimates of
      surface temperature using the slant-path geometry were within the range of
      values given by previous studies which measured active lava channels at
      0-70 metres distance; however, the complexity of the atmospheric model
      associated with this viewing geometry made it difficult to automate. Some
      errors resulted from the large pixel area (25 m2 ) of the long-range
      thermal data resulting in a greater area of temperature integration. The
      radiant heat flux profiles produced by the workflow followed the same
      trends as the SEVIRI-derived profile, although the intensity of the
      SEVIRI-derived profile was up to five times greater than the workflow
      profiles.