Displacements and tilts from dip‐slip faults and magma chambers beneath irregular surface topography

McTigue, D. F.; Segall, P.

doi:10.1029/gl015i006p00601

Cited by 68 publications

(49 citation statements)

References 9 publications

(3 reference statements)

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“…Several studies on the topographic effect ͑McTigue and Stein, 1984;McTigue and Segall, 1988;Cayol and Cornet, 1998;Williams and Wadge, 1998;Folch et al, 2000;Charco et al, 2002;Trasatti et al, 2003;Lungarini et al, 2005͒ support the conclusions that topography has a significant effect on the deformation field and that in many cases the flat half-space approximation could lead to erroneous interpretation of observed ground deformation.…”

Section: The Effect Of Topographymentioning

confidence: 82%

4D volcano gravimetry

Gottsmann²,

et al. 2008

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Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast ͑hours to weeks͒, as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera ͑California, U.S.A.͒ and Campi Flegrei ͑Italy͒, careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological interpretations, particularly when the real crust surrounding the source is far from the homogeneous/isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located ͑e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography͒. Applications at Teide volcano ͑Tenerife͒ and Campi Flegrei demonstrate the importance of this more realistic description in gravity calculations.

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Section: The Effect Of Topographymentioning

confidence: 82%

4D volcano gravimetry

Gottsmann²,

et al. 2008

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“…While such models have been quite successful at fitting surface measurements, it is clear that local topographic relief can introduce misinterpretation into source parameter estimation. MCTIGUE and STEIN (1984) and MCTIGUE and SEGALL (1988) studied the effect of topography by means of a two-dimensional model. CAYOL and CORNET (1998) and WADGE (1998, 2000) calculated the effect of the volcanic relief caused by a dilatational source in a purely elastic medium.…”

Section: Introductionmentioning

confidence: 99%

Some Insights into Topographic, Elastic and Self-gravitation Interaction in Modelling Ground Deformation and Gravity Changes in Active Volcanic Areas

Charco

Fernández

Luzón

et al. 2007

Pure appl. geophys.

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Surface displacements and gravity changes due to volcanic sources are influenced by medium properties. We investigate topographic, elastic and self-gravitation interaction in order to outline the major factors that are significant in data modelling. While elastic-gravitational models can provide a suitable approximation to problems of volcanic loading in areas where topographic relief is negligible, for prominent volcanoes the rough topography could affect deformation and gravity changes to a greater extent than self-gravitation. This fact requires the selection, depending on local relief, of a suitable model for use in the interpretation of surface precursors of volcanic activity. We use the three-dimensional Indirect Boundary Element Method to examine the effects of topography on deformation and gravity changes in models of magma chamber inflation/deflation. Topography has a significant effect on predicted surface deformation and gravity changes. Both the magnitude and pattern of the geodetic signals are significantly different compared to half-space solutions. Thus, failure to account for topographic effects in areas of prominent relief can bias the estimate of volcanic source parameters, since the magnitude and pattern of deformation and gravity changes depend on such effects.

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“…In particular, McTigue and Segall [1988], investigated the effects of topography on surface displacements by using a plane-symmetric approximation. Cayol and Cornet [1998] considered an axial symmetrical volcano with average slopes of flanks ranging from 0° to 30° and they showed that the flattening of the deflation in the summit area is probably a topographic effect: the steeper the volcano, the lower the central uplift.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Influence of topography on ground deformation at Mt. Vesuvius (Italy) by finite element modelling

Meo

Tammaro

Capuano

2008

International Journal of Non-Linear Mechanics

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Ground deformations are observed in connection with volcanic activity, and therefore geodetic monitoring can provide significant indication of changes of equilibrium conditions. The aim of this paper is to study the deformation of Mount Vesuvius (Italy) caused by overpressure sources at various depths, using a commercial (Ansys) 3D finite element code, in the framework of linear elastic isotropic material behaviour. Both homogenous and heterogeneous media with carbonate basement were analyzed to understand the influence of topography on the ground deformations. The topography of the Somma-Vesuvius was taken into account, using a digital terrain model, and the carbonate basement was schematically modelled by assuming two horizontal layers with different Young moduli. The presence of a strong deviation from axially symmetric pattern of the displacement field, and of small subsidence areas, was found. These characteristics are completely unknown from the simple Mogi model and by simplified topography model, as verified by ad hoc simulations. These preliminary results, showing areas of the volcanic edifice experiencing high deformation, can improve the determination of the sources of deformations, i.e. the most relevant problem in the volcano monitoring. Moreover, the knowledge of the deformation pattern, including the topography effects, can provide significant indications to optimize the A c c e p t e d m a n u s c r i p t location of sensors and the characteristics needed to design an efficient and reliable geodetic monitoring network able to detect shallow intrusion events.

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Displacements and tilts from dip‐slip faults and magma chambers beneath irregular surface topography

Cited by 68 publications

References 9 publications

4D volcano gravimetry

4D volcano gravimetry

Some Insights into Topographic, Elastic and Self-gravitation Interaction in Modelling Ground Deformation and Gravity Changes in Active Volcanic Areas

Influence of topography on ground deformation at Mt. Vesuvius (Italy) by finite element modelling

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