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

中文翻译：

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正应力对水镁石摩擦行为的影响：在地幔楔俯冲板界面慢地震中的应用

我们报告了在各种法向应力（10–60 MPa）下在干湿条件下水镁石的摩擦实验结果 。独立于法向应力，干和湿情况下水镁石的最终摩擦系数分别确定为0.40和0.26。在干燥条件下，所有实验在不同的正应力下均观察到速度减弱行为。在潮湿条件下，在低法向应力（10和20 MPa）下观察到速度减弱 ），而速度增强是在较高的法向应力下确定的。回收的实验样品的微观结构观察表明，在狭窄的剪切带内发生局部变形，这意味着少量的水镁石可以控制超镁铁矿环境下的整体摩擦强度。在蛇纹岩相关矿物中，水合地幔楔条件下水镁石的弱而不稳定的摩擦行为可能在地幔楔俯冲板界面缓慢地震中起作用。