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Title: The influence of volcanic systems on the morphological evolution of lava flow fields
Author: Hughes, Jenkin Wyn
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1992
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This thesis presents the results of a detailed study of the volcanic system of Mount Etna, Sicily, in the 1600 to 1689 and post-1750 periods of magmatic output. The conditions which prevailed within the volcanic system are ascertained, and their influence on the intra-volcano movement of magma constrained. The examination is extended to the superficial emplacement and planimetric evolution of the lava flow fields. In the post-1750 period, there was a marked sectorial control on eruptive styles at the surface, with large volume ( > 55 x 10 6 m3), long duration (32 days) and flow field (Type B)producing eruptions being generally restricted to the eastern sector. Western sector eruptions generally produced flow unit (Type A) lava flows and were of smaller volume and shorter duration. This dichotomy is interpreted to reflect interaction between the high level plumbing system and an asymmetric high level gravitational stress field. No sectorial dichotomy existed in the 17th century period, an observation which is attributed to the superposition of a more prominent basement tectonic stress field on the gravitational stress field. These changes in internal conditions are interpreted to have coincided with a shift in the regional tectonic stress regime below Etna. Though the predominant stress fields have varied, it is argued that the factors controlling the emplacement of the lava flows were common to both systems. A morphometric study of post-1600 lava flows establishes that the planimetric evolution of lava flows occurs in response to a temporally decaying effusion rate, and that the variety of final flow field morphologies, from aa channel-fed flow units to the pahoehoe tumulus flow fields, mostly reflect stages of systematic planimetric development along a single evolutionary trend. The change in effusion rate is itself, considered to be related to a temporal change in the magnitude and location of the principal eruptive mechanism within the volcanic system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available