Open AccessGround deformation in a viscoelastic medium composed of a layer overlying a half‐space: a comparison between point and extended sources
Author(s) -
Folch Arnau,
Fernández José,
Rundle John B.,
Martí Joan
Publication year - 2000
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.1365-246x.2000.00003.x
Subject(s) - viscoelasticity , laplace transform , half space , standard linear solid model , point source , mathematical analysis , rheology , finite element method , displacement (psychology) , rotational symmetry , matrix (chemical analysis) , geometry , deformation (meteorology) , hankel transform , point (geometry) , geology , mathematics , fourier transform , physics , materials science , optics , oceanography , composite material , psychology , psychotherapist , thermodynamics
We obtain and compare analytical and numerical solutions for ground displacement caused by an overpressurized magma chamber placed in a linear viscoelastic medium composed of a layer over a half‐space. Different parameters such as size, depth and shape of the chamber, crustal rheology and topography are considered and discussed. Numerical solutions for an axisymmetric extended source are computed using a finite element method (FEM). Analytical solutions for a point source are obtained using the dislocation theory and the propagator matrix technique. In both cases, the elastic solutions are used together with the correspondence principle of linear viscoelasticity to obtain the solution in the Laplace transform domain. Viscoelastic solutions in the time domain are derived inverting the Laplace transform using the Prony series method. The differences between the results allow us to constrain the applicability of the point source and the flat surface hypothesis, which are usually implicitly assumed when analytical solutions are derived. The effect of the topography is also considered. The results obtained show that neglecting the topographic effects may, in some cases, introduce an error greater than that implicit in the point‐source hypothesis. Therefore, for an adequate modelling and interpretation of the time‐dependent displacements, topography must be considered.