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Numerical evidences enabling to reconcile gravity and height changes in volcanic areas
Language
English
Obiettivo Specifico
4V. Vulcani e ambiente
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/197 (2014)
ISSN
0956-540X
Electronic ISSN
1365-246X
Publisher
Wiley-Blackwell
Pages (printed)
164-173
Issued date
2014
Keywords
Abstract
Gravity and height changes, reflecting magma accumulation in subsurface chambers, are evaluated using Finite Element models in order to resolve controversial relationships observed in some volcanic areas. When significant gravity changes occur without any significant deformation, or vice versa, it is often difficult, if not impossible, to jointly explain the observations using the popular Mogi model. Here we explore whether these discrepancies can be explained by magma compressibility and source geometry effects. Compression of resident magma and expansion of the chamber wall act concurrently to accommodate newly added magma. Gravity-height ratios are found to mainly depend on: (i) geometry of the sources, which control the volume expansion of the chamber, (ii) magma compressibility, which affects the contraction of the magma resident in the chamber, and (iii) depth of the sources. Our numerical results show that, when magma compressibility and non-spherical sources are taken into account, significant gravity variations can, indeed, be successfully reconciled with negligible height changes. This may be the case at Etna volcano, where gravity changes (about 40 miuGal) without any significant deformation (below 5 cm) were observed during the 1994-1995 inflation period. The numerical results point to the accumulation of a 1.4x10^10 kg mass into an elongated source simulating a shallow storage region supplying the summit craters.
Type
article
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Name
Currenti GJI 2014.pdf
Size
2.32 MB
Format
Adobe PDF
Checksum (MD5)
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