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Influence of crustal heterogeneities on stress fields and surface deformation induced by magmatic intrusions: insights from the Andes

Matías Clunes1,2, John Browning2,3, José Cembrano2, Carlos Marquardt3, Janine Kavanagh4, Agust Gudmundsson5

  • Affiliations: 1 School of the Environment and Life Sciences, University of Portsmouth, Portsmouth, UK 2 Department of Structural and Geotechnical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile 3 Department of Mining Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile 4 Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK 5 Department of Earth Sciences, Royal Holloway University of London, Egham, UK 

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 190

  • Programme No: 1.8.21

  • Theme 1 > Session 8

Abstract

In orogenic regions like the Andean Cordillera, volcanic edifices often form on a crust composed of dipping and mechanically heterogeneous rock layers. On this basis, magmatic intrusions and magma reservoirs are emplaced and propagate through a crust which is far from homogeneous or isotropic, assumptions frequently used in the study of volcanic stress fields and deformation. This study investigates how crustal heterogeneities influence the stress field and surface deformation induced by magmatic emplacement and propagation.  We combined field observations with Finite Element Method (FEM) models and analogue experiments using gelatine and water as crust and magma analogues, respectively. Our results demonstrate that dipping heterogeneous rock layers can significantly modify stress field induced by magmatic intrusions, altering intrusion geometries and the potential location of new eruptive vents. Tensile stress magnitudes at the surface were amplified by up to 40 times, and the location of maximum stress locations were shifted observed by as much as 1.4 km compared to a homogeneous crust.  Additionally, crustal heterogeneities generated asymmetrical surface deformation profiles for vertically propagating dykes, resembling the patterns observed in inclined sheets within a homogeneous crust. These findings emphasize the importance of accurately characterizing subsurface geology to improve interpretations of volcano dynamics during unrest to enhance monitoring efforts.