Multiobjective genetic algorithm inversion of ground deformation and gravity changes spanning the 1981 eruption of Etna volcano

During the last few decades, joint investigations of microgravity and surface deformation measurements have played an increasingly important role in studying the internal dynamics of active volcanoes. Deformation and microgravity observations have been accomplished at Mt Etna since the eighties. Pas...

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Bibliographic Details
Published in:Journal of Geophysical Research. B. Solid Earth Vol. 113; no. B7
Main Authors: Carbone, Daniele, Currenti, Gilda, Del Negro, Ciro
Format: Journal Article
Language:English
Published: Washington, DC Blackwell Publishing Ltd 01.07.2008
American Geophysical Union
Subjects:
Earth sciences
Earth, ocean, space
Exact sciences and technology
Genetic algorithm
gravity changes
ground deformation
Southern Europe
Italy
Marches Italy
Europe
fissures
wavelength
models
inverse problem
joints
eruptions
volcanoes
case studies
magmas
leveling
monitoring
lead
Deformation measurement
amplitude
dynamics
microfractures
Genetic algorithm
optimization
displacements
deformation
Distance measurement
Composite analysis
Gravity
ISSN:0148-0227, 2156-2202
Online Access:Get full text
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Summary:During the last few decades, joint investigations of microgravity and surface deformation measurements have played an increasingly important role in studying the internal dynamics of active volcanoes. Deformation and microgravity observations have been accomplished at Mt Etna since the eighties. Past data sets collected during important paroxysmal events can be utilized as case‐studies to both (1) test the possibilities of nowadays more powerful inversion tools and improved analytical formulations to model the source‐mechanisms of volcano‐related deformation and gravity changes and (2) in turn obtain new insights into the functioning of the plumbing system of the volcano. Here we analyze a data set spanning the March 1981 eruption of Mt. Etna. Large horizontal displacements were evidenced on the NE and SW flanks of the volcano through electrooptical distance measurements (EDM) during two 20‐month periods, both encompassing the March 1981 eruption. Elevation changes, evidenced through leveling measurements, during a 12‐month period spanning the eruption, were in general smaller than horizontal displacements with important amplitudes only close to the eruptive fissure. Gravity measurements, carried out together with leveling measurements, evidenced positive changes, spatially well correlated with elevation changes, but having a larger wavelength. The joint inversion of the multimethod geophysical data is regarded as a multiobjective optimization problem and solved through a Genetic Algorithm technique of the nondominated type. We conclude that a composite intrusive mechanism with two tensile cracks, each associated to a zone where preexisting microfractures were filled with new magma, leaded to the 1981 eruption. The results of the present study highlight the advantages of multiobjective evolutionary algorithms, as a powerful tool to jointly invert multimethod geophysical data, and pose important issues on the subject of volcano‐monitoring.
Bibliography:ark:/67375/WNG-6DCSGSRK-S
istex:D2977B2E14F50E06C247B2090C47003BE49B8452
ArticleID:2006JB004917
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ISSN:0148-0227
2156-2202
DOI:10.1029/2006JB004917