The role of cohesion in fault slip style

断层带内部和周围的岩石和沉积物的剪切强度控制着断层是稳定地移动，还是不稳定地移动，造成潜在的破坏性地震。抗剪强度有两部分：摩擦力，即表面在压力作用下对滑动的阻力；还有凝聚力，这是一种内在的力量，它存在于表面完全没有载荷的情况下。到目前为止，以往的断层研究几乎只关注摩擦对断层运动的控制，而忽略了断层的粘聚作用。然而，内聚性可能是断层的一个重要数量，主要有两个原因：(1)地震往往发生在坚硬的岩石化岩石中，而不是沉积物中；(2)以前的实验表明，粘滑滑动（一种实验室地震）往往发生在坚硬的岩质中。直接内聚力测量是罕见的，但我们已经开发了一个行之有效的方法，成功的测量在马鲁姆实验室。在此，我们建议建立系统的内聚力测量数据集，并探讨内聚力在发震断层滑动中的作用。我们将使用来自ICDP项目的钻井样本，这些项目可能包括新西兰的阿尔卑斯断层、圣安德烈亚斯断层、阿曼蛇绿岩、北安那托利亚断层和瑞典的Pärvie断层系统。其他测试材料可能包括来自美国俄克拉何马州的基底岩石，来自日本Shimanto带的挖掘断层岩石，以及各种普通岩石和纯矿物，用作测试标准。主要目标是收集一致条件下各种岩石类型的粘聚力测量结果，并将这些测量结果与相同条件下相同岩石类型的常规摩擦实验结果进行比较。在这个整体项目的基础上，我们将开展更有针对性的子项目，旨在研究特定条件如何影响内聚性，并评估这对断层滑动意味着什么。这些特定条件包括：温度、压力、流体的存在、滑动速度和岩石结构。这些测试的结果将使我们能够比较内聚力与摩擦力的相对重要性，内聚力可能成为理解断层运动和地震的一个新的有力工具。

The shear strength of rocks and sediments in and around fault zones controls whether the fault moves stably, or unstably as potentially damaging earthquakes. Shear strength has two parts: friction, which is the resistance to sliding for surfaces under pressure; and cohesion, which is an intrinsic strength that exists when the surfaces are completely unloaded. Up to now, previous fault studies have focused almost exclusively on how friction controls fault movement, but ignore the cohesion. However, cohesion is likely an important quantity for faults, for two main reasons: (1) earthquakes tend to occur in hard, lithified rocks rather than sediments, and (2) previous experiments show that stick-slip sliding, which is a laboratory earthquake, tends to occur in hard, competent rocks. Direct cohesion measurements are rare, but we have developed a proven method for successful measurements in the Marum laboratory. Here, we propose to conduct a systematic dataset of cohesion measurements, and to explore the role of cohesion in seismogenic fault slip. We will use drilling samples from ICDP projects, which may include the Alpine Fault in New Zealand, the San Andreas Fault, the Oman Ophiolite, the North Anatolian Fault and the Pärvie Fault System in Sweden. Other test materials may include basement rock from Oklahoma, USA, exhumed fault rock from the Shimanto Belt, Japan, and a variety of common rocks and pure minerals, used as testing standards. The main goal is to assemble cohesion measurements for a wide range of rock types under consistent conditions, and compare these measurements with the results of more conventional friction experiments on the same rock types under the same conditions. Based on this overall project, we will conduct more focused sub-projects aimed at how specific conditions affect cohesion and evaluate what this means for fault slip. These specific conditions include: temperature, pressure, the presence of fluid, sliding speed, and rock fabric. The results of these tests will allow us to compare the relative importance of cohesion compared to friction, with cohesion being a possible new powerful tool for understanding fault motion and earthquakes.