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Stresses induced by magma chamber inflation altered by mechanical layering and layer dip
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  • Matías Clunes,
  • John Browning,
  • Jorge Cortez,
  • José Cembrano,
  • Carlos Marquardt,
  • Janine Kavanagh,
  • Agust Gudmundsson
Matías Clunes
Pontificia Universidad Católica de Chile

Corresponding Author:mclunes@uc.cl

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John Browning
Pontificia Universidad Catolica de Chile
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Jorge Cortez
Universidad de La Serena
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José Cembrano
Pontificia Universidad Católica de Chile
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Carlos Marquardt
Pontificia Universidad Católica de Chile
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Janine Kavanagh
School of Environmental Science - University of Liverpool, Liverpool
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Agust Gudmundsson
Royal Holloway University of London
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Understanding the stress distribution around shallow magma chambers is vital for predicting eruption sites and magma propagation directions. To achieve accurate predictions, comprehensive insight into the stress field surrounding magma chambers and near the surface is essential. Existing stress models for magma chamber inflation often assume a homogenous elastic half-space or a heterogeneous crust with varying mechanical properties in horizontal layers. However, as many volcanoes have complex, non-horizontal, and heterogeneous layers, we enhance these assumptions by considering mechanically diverse layers with varying dips. We employed the Finite Element Method (FEM) to create numerical models simulating two chamber shapes: a circular form and a sill-like ellipse. The primary condition was a 10 MPa excess pressure within the magma chamber, generating the stress field. Layers dips by 20-degree increments, with differing elastic moduli, represented by stiffness ratios (EU/EL) ranging from 0.01 to 100. Our findings validate prior research on heterogeneous crustal modeling, showing that high stiffness ratios disrupt stress within layers and induce local stress rotations at mismatched interfaces. Layer inclination further influences stress fields, shifting the location of maximum stress concentration over varying distances. This study underscores the significance of accurately understanding mechanical properties, layer dip in volcanoes, and magma chamber geometry. Improving predictions of future eruption vents in active volcanoes, particularly in the Andes with its deformed, folded, and non-horizontal stratified crust, hinges on this knowledge. By expanding stress models to incorporate complex geological structures, we enhance our ability to forecast eruption sites and the paths of magma propagation accurately.
06 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive