The role of cohesion in fault slip style

黏聚力在断层滑动样式中的作用

• 批准号: 457003631
• 负责人: Dr. Matt Ikari, Ph.D.
• 金额: --
• 依托单位: Zentrum für Marine Umweltwissenschaften (MARUM)
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/457003631?language=en
• 关键词: role; cohesion; fault; slip; style

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.

断层带内和周围岩石和沉积物的剪切强度控制着断层是稳定移动，还是不稳定地移动，从而产生潜在的破坏性地震。 抗剪强度分为两部分：摩擦力，它是在压力下表面的滑动阻力;以及内聚力，它是当表面完全卸载时存在的内在强度。 到目前为止，以往的断层研究几乎只关注摩擦力如何控制断层运动，而忽略了凝聚力。 然而，凝聚力可能是断层的一个重要量，主要有两个原因：（1）地震往往发生在坚硬的石化岩石中，而不是沉积物中;（2）以前的实验表明粘滑滑动，这是一种实验室地震，往往发生在坚硬的岩石中。直接的内聚力测量是罕见的，但我们已经开发出一种行之有效的方法，在Marum实验室成功的测量。 在这里，我们建议进行一个系统的数据集的凝聚力测量，并探讨凝聚力在孕震断层滑动的作用。 我们将使用ICDP项目的钻探样品，其中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、北安纳托利亚断层和瑞典的帕尔维断层系统。 其他测试材料可能包括来自美国俄克拉荷马州的基底岩石、来自日本Shimanto带的挖掘出的断层岩以及用作测试标准的各种普通岩石和纯矿物。主要目标是在一致的条件下为各种岩石类型收集凝聚力测量值，并将这些测量值与相同条件下相同岩石类型的更传统的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凝聚力，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、滑动速度和岩石组构。 这些测试的结果将使我们能够比较凝聚力与摩擦力的相对重要性，凝聚力可能是理解断层运动和地震的新的有力工具。