Publication Date

2018-04-26

Availability

Open access

Embargo Period

2018-04-26

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Marine Geology and Geophysics (Marine)

Date of Defense

2017-11-08

First Committee Member

Falk Amelung

Second Committee Member

Guoqing Lin

Third Committee Member

Shimon Wdowinski

Fourth Committee Member

Patricia Gregg

Abstract

Geophysical techniques were applied to active volcanoes in Colombia, Ecuador, Peru and the Philippines in order to identify surface deformation, evaluate the sources of deformation, and gain a better understanding of volcanic systems through integration of multidisciplinary observations and improved source modeling methods. The main technique that was used for deformation measurements was time series analysis of Interferometric Synthetic Aperture Radar (InSAR) data, which was applied over 55 volcanoes and revealed deformation at 8 volcanoes related to subsidence of volcanic deposits, flank instability, and magmatic or hydrothermal activity. For volcanoes with deformation related to the latter two, InSAR data was inverted to determine the best- fitting sources of deformation at the subsurface. Global positioning system (GPS) and seismic data were also used for InSAR measurement validation, interpretation, and to estimate better representations of subsurface properties and processes. Improved modeling techniques were applied to one of the deforming volcanoes, taking more realistic representations of subsurface thermomechanical properties to evaluate viscoelastic deformation scenarios and to define plausible values for rheological properties within volcanic systems. This information is critical for future studies that aim to understand various volcanic processes, including crustal deformation, magma chamber failure, and intrusion propagation, and ultimately eruption forecasting. Fixed and varied parameters, including seismically constrained elastic constants, geothermal gradients, Dorn parameter, activation energy, viscosity distributions, magma chamber temperature, radius, depth, and overpressure, were examined to investigate the crustal response variations and the implications at the local geologic setting. These improved models provided significantly better results than those used in typical volcano deformation studies, and realistic approximations of subsurface properties in volcanic systems of different geologic settings.

Keywords

Volcano deformation; InSAR time series; Modeling; Andes; Philippines

Data Set A1.xls (158 kB)
Supplementary data set for chapter 2

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