Solid Earth | 2021
Effect of normal stress on the frictional behavior of brucite: application to slow earthquakes at the subduction plate interface in the mantle wedge
Abstract
Abstract. We report the results of friction experiments on brucite under both dry and wet conditions under various normal stresses (10–60\u2009 MPa ). The\nfinal friction coefficients of brucite were determined to be 0.40 and 0.26 for the dry and wet cases, respectively, independent of the normal\nstress. Under dry conditions, velocity-weakening behavior was observed in all experiments at various normal stresses. Under wet conditions, velocity\nweakening was observed at low normal stress (10 and 20\u2009 MPa ), whereas velocity strengthening was determined at a higher applied normal\nstress. Microstructural observations of recovered experimental samples indicate localized deformation within a narrow shear band, implying that a\nsmall volume of brucite can control the bulk frictional strength in an ultramafic setting. Among serpentinite-related minerals, weak and unstable\nfrictional behavior of brucite under hydrated mantle wedge conditions may play a role in slow earthquakes at the subduction plate interface in\nthe mantle wedge.