Intermediate-depth earthquake generation and shear zone formation caused by grain size reduction and shear heating
cited By 23; The underlying physics of intermediate-depth earthquakes have been an enigmatic topic; several studies support either thermal runaway or dehydration reactions as viable mechanisms for their generation. Here we present fully coupled thermomechanical models that investigate the impact of grain size evolution and energy feedbacks on shear zone and pseudotachylite formation. Our results indicate that grain size reduction weakens the rock prior to thermal runaway and significantly decreases the critical stress needed for thermal runaway, making it more likely to result in intermediate-depth earthquakes at shallower depths. Furthermore, grain size is reduced in and around the shear z…
Combined numerical and experimental study of microstructure and permeability in porous granular media
<div> <div> <div> <p>Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities, representing shallow depth crustal sediments. The microstructure, namely effective porosity …
Shear heating induced lithospheric-scale localization: Does it result in subduction?
Abstract Even though it is a well-established fact that the Earth is currently in a plate-tectonics mode, the question on how to “break” lithospheric plates and initiate subduction remains a matter of debate. Here we focus on shear heating as a potential mechanism to cause lithospheric shear localization and subsequent subduction initiation in oceanic plates. It is shown that shear heating under some conditions (i) facilitates the formation of a lithospheric-scale shear zone and (ii) is capable of stabilizing a lithospheric-scale shear zone, thus creating the necessary condition for subduction initiation to occur. Furthermore, we demonstrate that not only the localization process is of impo…