Title:
|
Constraining volcanic unrest with integrated geodetic modelling
|
A comprehensive understanding of the origin, nature, and significance of volcanic unrest is
currently missing, but of fundamental imp0l1ance to communities living with the threat of
volcanic hazards. My thesis addresses this shortcoming from a volcanic deformation angle.
By incorporating a range of multi-disciplinary data, I have developed new integrated models
of volcanic deformation using Finite Element Analysis (FEA) that are suitable for use in both
forward and inverse modelling approaches. They are consistent with independent geophysical
observables and provide detailed insight on volcanic processes during unrest crises. I have
applied these models to three volcanoes. A study of Uturuncu volcano, Bolivia, highlighted
the importance of subsurface structure and time-dependent source processes in explaining both
the spatial and temporal deformation patterns. The combined results alluded to a diapiric-type
ascent of magma. At Cotopaxi volcano, Ecuador, I used novel inversion models employing
FEA to elucidate the location and volume of a magmatic intrusion during an aseismic, and non-eruptive,
unrest episode. The models also provided insights into observable signals that could
be associated with future intrusive or eruptive activity. My analysis of the persistent inflation
at Aira caldera, Japan, during an ongoing emptive phase at Sakurajima volcano, used inverse
Finite Element models to, for the first time, quantify the statistical significance of including
topography and subsurface heterogeneity in deformation models. Additional models results were
used to identify the rate, timing, volume, location and mechanism of magma supply, as well as
the timescales that could be associated with increases in future eruptive activity. Together, these
results highlight how models with more plausible, and geophysically consistent, components can
improve our understanding of the mechanical processes affecting volcanic unrest and geodetic
eruption precursors. They provide a framework to help advance emption forecasting and risk
mitigation.
|