BayStress4 is a package of MatLab routine, designed to constrain the state of stress of a volcanic system by means of posterior Probability Density Functions (PDFs) of the stress tensor components. To do so, it employs the model of three-dimensional (3D) dyke pathways developed by Mantiloni et al., 2023 (SAM: Simplified Analytical Model of dyke Pathways in Three Dimensions) to match the known locations of past eruptive vents to the known or assumed volume in the subsurface ("Dyke nucleation zone" or "D") where their parent dykes nucleated from. This is achieved by a) using SAM to backtrack dyke pathways from the vents down through the crust for a given stress model; b) quantifying the intersection between such pathways and D through a misfit function; c) using this procedure to run a Markov Chain Monte Carlo (MCMC) algorithm to sample the stress parameters' space. The posterior information provided by the stress inversions can then be used to produce forward simulations of dyke pathways with SAM and forecast the surface distribution of future eruptive vents across the volcanic system.
This repository contains InVent4Cast, a package of MatLab routines designed to constrain the state of stress of a volcanic system by means of posterior Probability Density Functions (PDFs) of the stress tensor components. To do so, it employs the model of three-dimensional (3D) dyke pathways developed by Mantiloni et al., 2023a (SAM: Simplified Analytical Model of dyke Pathways in Three Dimensions) to match the known locations of past eruptive vents to the known or assumed volume in the subsurface ("Dyke nucleation zone" or "D") where their parent dykes nucleated from. This is achieved by a) using SAM to backtrack dyke pathways from the vents down through the crust for a given stress model; b) quantifying the intersection between such pathways and D through a misfit function; c) using this procedure to run a Markov Chain Monte Carlo (MCMC) algorithm to sample the stress parameters' space. The posterior information provided by the stress inversions can then be used to produce forward simulations of dyke pathways with SAM and forecast the surface distribution of future eruptive vents across the volcanic system.
The repository also collects data, figures and results of the application of InVent4Cast to some of the synthetic scenarios of dyke pathways in calderas presented by Mantiloni et al., 2023a. These results were detailed and discussed by Mantiloni et al., 2024a, to which the reader is referred for further information. The synthetic scenarios include numerical models of crustal stress state, focusing on gravitational loading/unloading due to topography and tectonic processes as the dominant stress sources. These stress sources are accounted for by a set of stress parameters. Results include posterior probability density functions (PDFs) of such stress parameters after applying the stress inversion to the scenarios, as well as probability maps of eruptive vent opening across the synthetic volcanic areas. Synthetic scenarios, stress inversions and vent forecasts were produced between May 2022 and November 2023.
SAM ("Simplified Analytical Model") is a MatLab-based software that allows for fast and flexible simulations of three-dimensional dyke pathways in an elastic medium. The model was first introduced in "Mechanical modeling of pre-eruptive magma propagation scenarios at calderas" (Mantiloni, L. et al. 2023). In SAM, dykes are modelled as penny-shaped cracks of fixed radius, opening against the local direction of the least-compressive principal stress. The direction of propagation is determined by the gradient of the external stress normal to the crack's plane and the buoyancy force of the magma filling the dyke, calculated at a set of observation points along the crack's tipline. The model can also include a uniform internal pressure within the dyke and compute the stress intensity factor along the crack's tipline, comparing it to the fracture toughness of the host rock to determine if the dyke will advance. SAM needs a model for the stress field of the host rock as input, as well as magma and rock densities, rock elastic properties, the dyke's radius and the number of observation points. The model may be applied to simulate dyke pathways in realistic volcanic settings with different stress sources, and can perform large numbers of simulations in little time. The model does not, however, account for any viscous flow of magma within the dyke, nor the velocity of dyke propagation. Dykes cannot change shape or area during the propagation, and are always bound to be oriented normally to the local least-compressive principal stress axis. This repository also includes data and parameters of the synthetic scenarios discussed in "Mechanical modeling of pre-eruptive magma propagation scenarios at calderas".