A Model to Forecast the Path of a Laterally Propagating Dike

Abstract:

An important aspect of eruption forecasting is predicting the path of propagating dikes. We have developed a method, which applies the minimum potential energy principle, for forecasting the path of laterally propagating dikes given the starting point of propagation. The method is computationally feasible and can be used to form a probability distribution for dike location in near-real time. We have compared our model to the propagation of the 2014 and 1996 dikes in the Bardarbunga volcanic system, Iceland. We found good agreement between predicted and observed propagation. Topography is very important for the model and our preferred forecasting model combines strain energy change of the crust and considers pressure gradients due to topography. We tested the influence of topography by running the model assuming no topography and found the path of the 2014 dike could not be hindcasted. The results suggest that not only is lateral dike propagation governed by deviatoric stresses but also pressure gradients and may, to lesser extent, be influenced by gravitational energy. Furthermore, the model predicts the formation of curved dikes around cone shape structures without the assumption of local deviatoric stress field. We suggest that a likely eruption site for a laterally propagating dike is in a topographic low. The method presented here is simple and computationally feasible. Our results indicate that this kind of a model can be applied to mitigate volcanic hazards in regions where the tectonic setting promotes formation of laterally propagating vertical intrusive sheets.