Physics-based models of ground deformation and extrusion rate at effusively erupting volcanoes

Abstract

[1] We present a model of effusive silicic volcanic eruptions which relates magma chamber and conduit physics to time-dependent data sets, including ground deformation and extrusion rate. The model involves a deflating chamber which supplies Newtonian magma through a cylindrical conduit. Solidification is approximated as occurring at fixed depth, producing a solid plug that slips along its margins with rate-dependent friction. Changes in tractions acting on the chamber and conduit walls are used to compute surface deformations. Given appropriate material properties and initial conditions, the model predicts the full evolution of an eruption, allowing us to examine the dependence of observables on initial chamber volume, overpressure, and volatile content. Employing multiple data sets in combination with a physics-based model allows for better constraints on these parameters than is possible using kinematic idealizations. Modeling posteruptive deformation provides an improved constraint on the rate of influx into the magma chamber from deeper sources. We compare numerical results to analytical approximations and to data from the 2004-2008 eruption of Mount St. Helens. For nominal parameters the balance between magma chamber pressure and frictional resistance of the solid plug controls the evolution of the eruption, with little contribution from the fluid magma below the idealized crystallization depth. While rate-dependent plug friction influences the timedependent evolution of the eruption, it has no control on the final chamber pressure or extruded volume.Citation: Anderson, K., and P. Segall (2011), Physics-based models of ground deformation and extrusion rate at effusively erupting volcanoes,

Bayesian inversion of data from effusive volcanic eruptions using physics‐based models: Application to Mount St. Helens 2004–2008

“…[44] Non-estimated parameter values are taken from Anderson and Segall [2011] unless otherwise noted. For a shallow edifice density ( l in equation (9a), which influences normal stress on the plug), we use 2150 kg/m 3 [Williams et al, 1987].…”

“…In order to use these models in an inversion, they must relate changes in pressures and tractions in magma to stresses and strains in the host rock in order to predict observations such as ground deformation. Anderson and Segall [2011] (hereafter referred to as Part 1) developed a relatively simple numerical, physics-based In this study the model is constrained by observations of ground deformation and lava dome extrusion, but other types of data such as CO 2 emissions and gravity could also be considered.…”

Abstract volume for the 2016 biennial meeting of the Yellowstone Volcano Observatory

“…In particular, incorporating physicsbased eruption models into probabilistic frameworks can go a long way towards addressing some of the challenges listed above. If an eruption model is capable of predicting a diverse range of observations (Anderson and Segall, 2011), then a Bayesian inverse technique allows those observations, together with any available independent a priori information (derived from the results of previous studies) to be used to constrain model parameters (Anderson and Segall, 2013). This approach can be extended in a straightforward manner to yield a mixed deterministic-probabilistic eruption-forecasting framework (Segall, 2013), suitable for use with data assimilation techniques to incorporate evolving observations (Gregg and Pettijohn, 2016), which yields forecasts whose uncertainties are derived from uncertainties in initial conditions.…”

Global Volcano Monitoring: What Does It Mean When Volcanoes Deform?

“…Satellite techniques are rapidly improving our ability to monitor volcanoes on a global simplified geometries, to finite element models incorporating more complex rheological and structural information, to physics-based models capable of integrating geophysical monitoring with observations of degassing, petrology and so on (Masterlark, 2006;Anderson and Segall, 2011).…”