Mechanical Modeling of Pre-Eruptive Magma Propagation Scenarios at Calderas

Simulating magma propagation pathways requires both a well-calibrated model for the stress state of the volcano and models for dike advance within such a stress field. Here, we establish a framework for calculating computationally efficient and flexible magma propagation scenarios in the presence of caldera structures. We first develop a three-dimensional (3D) numerical model for the stress state at volcanoes with mild topography, including the stress induced by surface loads and unloading due to the formation of caldera depressions. Then, we introduce a new, simplified 3D model of dike propagation. Such a model captures the complexity of 3D magma trajectories with low running time, and can backtrack dikes from a vent to the magma storage region. We compare the new dike propagation model to a previously published 3D model. Finally, we employ the simplified model to produce shallow dike propagation scenarios for a set of synthetic caldera settings with increasingly complex topographies. The resulting synthetic magma pathways and eruptive vent locations broadly reproduce the variability observed in natural calderas.

Automated summary

This study establishes a computationally efficient and flexible magma propagation model, which considers the stress state of the volcano and the advancement of dike propagation within this stress field. A three-dimensional numerical model is developed to calculate the stress state of the volcano, and a simplified three-dimensional model of dike propagation is introduced. By comparing with a previous model, it is found that the new model better simulates dike propagation. Finally, the simplified model is used to produce shallow dike propagation scenarios in a series of synthetic caldera settings, which broadly reproduce the observed variability in natural calderas.