The weakest link: new methods to measure the strength of geological faults

最薄弱的环节：测量地质断层强度的新方法

• 批准号: RGPIN-2016-04677
• 负责人: Kirkpatrick, James
• 金额: $ 2.11万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=683290
• 关键词: weakest; link; new; methods; measure

More than half of the world's cities with 2-15 million people are at risk from earthquakes of magnitude seven or greater. Recent devastating events in Haiti, Japan, and Nepal have highlighted that both developed and developing countries are exposed to high risks. Predicting earthquakes remains a distant goal for Earth scientists. One of the reasons is that the physical conditions and processes that control the strength and behavior of geological faults are unknown. These parameters cannot be measured with seismological or geophysical methods. My long-term research program aims to investigate fault strength and the tendency of faults to rupture in earthquakes by examining evidence from the rock record. By using fossil earthquakes' as representative of earthquakes that happen today, I can directly observe, characterize and measure the properties of faults where earthquakes initiated. Outstanding unknowns include: the absolute strength of faults, the degree of strength heterogeneity, and how the properties of the faults that host earthquakes control the characteristics of the ruptures.******Over the next five years, my core research questions will be: 1) How strong is a fault? 2) How important are the geometric boundary conditions in controlling fault behavior? I will examine these questions by integrating digital field data with numerical and laboratory experiments. These methods are novel, and I will build on my previous experience with digital mapping technologies to develop a new experimental capability by utilizing 3-D printing. Results arising from this multidisciplinary approach are potentially transformative. Three testable hypotheses will form the focus of two PhD, one Masters and five undergraduate research projects:*** The geometry of fault surfaces controls the strength and stability of faults;*** The characteristics of earthquakes depend on fault geometry;*** The strength of faults is recorded by structures preserved in deformed rocks.***The results will be the first step towards my career goal of developing new methodologies for investigating rock mechanics in the field and ultimately bridging the divide between structural geology and seismology.******The results will place constraints on the magnitudes of stresses that drive fault motions, which will address a long-standing problem in earthquake seismology and geodynamics. Additionally, they will establish for the first time how the geometry of faults influences fault stability, a key parameter in understanding the distribution of earthquakes globally. By addressing the fundamental controls on fault slip, this research will have significant national and international applicability to earthquake and tsunami hazard appreciation and risk mitigation.

世界上有200万至1500万人口的城市中有一半以上面临7级或更大地震的风险。最近在海地、日本和尼泊尔发生的破坏性事件突出表明，发达国家和发展中国家都面临高风险。预测地震对地球科学家来说仍然是一个遥远的目标。原因之一是控制地质断层强度和行为的物理条件和过程是未知的。这些参数无法用地震学或地球物理学方法测量。我的长期研究计划旨在通过检查岩石记录中的证据来调查断层强度和地震中断层破裂的趋势。以化石地震为代表的现代地震，可以直接观察、表征和测量地震发生的断层的性质。突出的未知数包括：断层的绝对强度、强度不均匀程度以及承载地震的断层的性质如何控制破裂的特征。在接下来的五年里，我的核心研究问题将是：1）故障有多强？2)几何边界条件在控制断层行为方面有多重要？我将通过将数字现场数据与数值和实验室实验相结合来研究这些问题。这些方法都是新颖的，我将根据我以前的经验与数字测绘技术，开发一个新的实验能力，利用3D打印。这一多学科方法产生的结果可能具有变革性。三个可验证的假设将形成两个博士，一个硕士和五个本科生研究项目的重点：* 断层表面的几何形状控制断层的强度和稳定性;* 地震的特征取决于断层的几何形状;* 断层的强度由变形岩石中保存的结构记录。这些结果将是我职业生涯目标的第一步，即开发新的方法来研究该领域的岩石力学，并最终弥合结构地质学和地震学之间的鸿沟。结果将限制驱动断层运动的应力大小，这将解决地震学和地球动力学中的一个长期问题。此外，他们将首次确定断层的几何形状如何影响断层稳定性，这是了解全球地震分布的关键参数。通过解决断层滑动的基本控制，这项研究将具有重大的国家和国际适用性，地震和海啸灾害评估和风险缓解。