Elastic models of magma reservoir mechanics: a key tool for investigating planetary volcanism

Abstract

Understanding how shallow reservoirs store and redirect magma is critical for deciphering the relationship between surface and subsurface volcanic activity on the terrestrial planets. Complementing field, laboratory and remote sensing analyses, elastic models provide key insights into the mechanics of magma reservoir inflation and rupture, and hence into commonly observed volcanic phenomena including edifice growth, circumferential intrusion, radial dyke swarm emplacement and caldera formation. Based on finite element model results, the interplay between volcanic elements – such as magma reservoir geometry, host rock environment (with an emphasis on understanding how host rock pore pressure assumptions affect model predictions), mechanical layering, and edifice loading with and without flexure – dictates the overpressure required for rupture, the location and orientation of initial fracturing and intrusion, and the associated surface uplift. Model results are either insensitive to, or can readily incorporate, material and parameter variations characterizing different planetary environments, and they also compare favourably with predictions derived from rheologically complex, time-dependent formulations for a surprisingly diverse array of volcanic scenarios. These characteristics indicate that elastic models are a powerful and useful tool for exploring many fundamental questions in planetary volcanology.

Three‐Dimensional Failure Patterns Around an Inflating Magmatic Chamber

“…However Corbi et al () for instance fit surface failure structures (radial faults and circumferencial dikes) by considering only the gravitational load of the edifice itself, and neglect the gravity force acting on the entire medium. Given our previous remarks (see also discussion in Grosfils et al, ), we would recommend to perform additional simulations that include the gravity force, and seek how to fit such failure patterns by integrating the whole temporal cycles of edifice building and caldera formation. Note that Currenti and Williams () account for gravity and show that the presence of an edifice increases the critical overpressure capable to generate chamber failure, independent on the reservoir's geometry.…”

Stress Triggering of the 2005 Eruption of Sierra Negra Volcano, Galápagos

“…As the reservoir geometry and location (an ellipsoid 0.4 km tall × 7 km wide centered at 3‐km depth) were constrained by previous geodetic studies (Amelung et al, ; Chadwick et al, ; Jonsson et al, ; Yun et al, ), we focus on the mass flux necessary to reproduce the uplift. Stability of the system is assessed by investigating the magnitude of the change in overpressure, the extent of Mohr‐Coulomb failure in the host rock, and the presence of tensile failure along the magma reservoir boundary (Gregg et al, , , ; Grosfils, ; Grosfils et al, ). Overpressure is calculated as the local force per area along the reservoir‐host rock interface with variable states of stress experienced for different regions of the interface.…”

“…While overpressure facilitates magma evacuation, failure in the host rock surrounding a magma system, and in particular tensile failure at the magma‐rock interface, is critical for catalyzing an eruption. As such, determining the stability of magma in storage by estimating host rock stress evolution is necessary for assessing eruption potential (Acocella, , ; Gerbault et al, ; Gregg et al, ; Grosfils, ; Grosfils et al, ; Marti et al, ).…”

Volcanism and tectonism across the inner solar system: an overview

“…Exploring the mechanics of magma storage, its ascent to the surface, and the interplay of subsurface and surface volcano-tectonic processes is the main objective of this contribution by Grosfils et al (2013). These authors use bespoke elastic numerical models that leverage field, laboratory and remotesensing observations to study volcanic processes on terrestrial worlds.…”