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Book Chapter

Applicability of InSAR to tropical volcanoes: Insights from Central America

By
S. K. Ebmeier
S. K. Ebmeier
1
COMET+, Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
2
COMET+, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK
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J. Biggs
J. Biggs
2
COMET+, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK
3
RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
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T. A. Mather
T. A. Mather
1
COMET+, Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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F. Amelung
F. Amelung
3
RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
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Published:
January 01, 2013

Abstract

Measuring volcano deformation is key to understanding the behaviour of erupting volcanoes and detecting those in periods of unrest. Satellite techniques provide the opportunity to do so on a global scale but, with some notable exceptions, the deformation of volcanoes in the tropics has been understudied relative to those at higher latitudes, largely due to technical difficulties in applying Interferometric Synthetic Aperture Radar (InSAR).

We perform a systematic survey of the Central American Volcanic Arc to investigate the applicability of Interferometric Synthetic Aperture Radar (InSAR) to volcanoes in the tropics. Volcano characteristics that may prevent InSAR measurement include: (1) dense vegetation cover; (2) persistent activity; and (3) steep slopes. Measurements of deformation are further inhibited by atmospheric artefacts associated with: (4) large changes in topographical relief. We present a systematic method for distinguishing between water vapour artefacts and true deformation. Our data show a linear relationship (c. 2 cm/km) between the magnitudes of water vapour artefacts and volcano edifice height. For high relief volcanoes (e.g. Fuego, Guatemala, 3763 m a.s.l. (above sea level)) errors are of the order of 4–5 cm across the volcano's edifice but are less than 2 cm for lower relief (e.g. Masaya, Nicaragua, 635 m a.s.l.). Examples such as Arenal, Atitlan and Fuego illustrate that satellite acquisition strategies incorporating ascending and descending tracks are particularly important for studying steep-sided volcanoes.

Poor coherence is primarily associated with temporal decorrelation, which is typically more rapid in southern Central America where Evergreen broadleaf vegetation dominates. Land-use classification is a better predictor of decorrelation rate than vegetation index. Comparison of coherence for different radar wavelengths match expectations; high resolution X-band radar is best suited to local studies where high-resolution digital elevation models (DEMs) exist, while L-band wavelengths are necessary for regional surveys. However, this is the first time that relationships between phase coherence and time, perpendicular baseline, radar wavelength, and land use have been quantified on the scale of a whole volcanic arc.

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Contents

Geological Society, London, Special Publications

Remote Sensing of Volcanoes and Volcanic Processes: Integrating Observation and Modelling

D. M. Pyle
D. M. Pyle
University of Oxford, UK
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T. A. Mather
T. A. Mather
University of Oxford, UK
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J. Biggs
J. Biggs
University of Bristol, UK
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Geological Society of London
Volume
380
ISBN electronic:
9781862396456
Publication date:
January 01, 2013

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