Geological Controls on the Seismic Cycle

地震周期的地质控制

• 批准号: RGPIN-2017-05266
• 负责人: Rowe, Christie
• 金额: $ 2.33万
• 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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633785
• 关键词: Geological; Controls; Seismic; Cycle

At present, scientists are not able to predict earthquakes, in part because we do not have a fundamental understanding of the earth processes which control when and where earthquakes occur and how big they are. Seismic waves shake the earth's surface and are detected by seismometers, which allow scientists to pinpoint the exact time and location of the fault rupture which caused the earthquake at depth within fault zones. I investigate the controls on earthquakes by identifying this earthquake source region in ancient fault zones which have been uplifted and exposed by erosion at the surface of the earth. Studying the earthquake source in situ within the rocks allows me to make observations on small scales (kilometers down to nanometers), which are the scales at which individual mineral grains break, melt, and react to control the rock properties during earthquakes, but which are beyond the limit of modern seismology. My approach involves significant time invested in exploration and discovery of new field areas where ancient faults are exposed, with the intention of opening up the breadth of variation across many types of fault systems to contribute to a more generalized understanding of earthquakes. The ancient faults allow me to study the geometry of slip surfaces and infer controls on the energy balance at depth during the seismic cycle. Using cutting-edge field techniques including drone aerial photography, I reconstruct a three-dimensional model of outcrops of ancient fault zones and use these to compare the fundamental geometry and length scales of ancient earthquake ruptures to the modern earthquake observations from seismology and geodesy. I identify the rock chemistry, mineralogy, and fluid-rock reactions which characterize these faults before, during and after earthquakes. Fluid-rock reactions in seismic faults are of particular importance to Quebec and Canada because these fluids are responsible for the deposition of some types of ore deposits, and earthquakes are events which can trigger the deposition of precious metals. By investigating a range of ancient fault sites in different rock types and tectonic settings, my research contributes to a general model for controls on the earthquake cycle across Canada and the rest of the world.

目前，科学家们还不能预测地震，部分原因是我们对控制地震发生的时间和地点以及地震大小的地球过程没有基本的了解。 地震波震动地球表面，并被地震仪检测到，这使科学家能够精确地确定断层破裂的确切时间和位置，这些断层破裂导致了断层带深处的地震。 我通过在古老的断层带中识别地震源区来研究地震的控制，这些断层带已经被抬升并暴露在地球表面的侵蚀中。 在岩石中原位研究震源使我能够在小尺度（从千米到纳米）上进行观察，这是单个矿物颗粒在地震中破碎、熔化并反应以控制岩石性质的尺度，但这超出了现代地震学的极限。 我的方法涉及大量的时间投入到勘探和发现新的领域领域，在那里古老的断层暴露，目的是开放的变化范围在许多类型的断层系统，以促进更广泛的理解地震。 古老的断层使我能够研究滑动面的几何形状，并推断在地震周期中对深度能量平衡的控制。使用包括无人机航空摄影在内的尖端现场技术，我重建了古代断层带露头的三维模型，并使用这些模型将古代地震破裂的基本几何形状和长度尺度与地震学和大地测量学的现代地震观测进行比较。 我确定了岩石化学，矿物学和流体岩石反应，这些断层的特点之前，期间和之后的地震。 地震断层中的流体-岩石反应对魁北克和加拿大特别重要，因为这些流体是某些类型矿床沉积的原因，而地震是可以触发贵金属沉积的事件。 通过调查不同岩石类型和构造环境中的一系列古代断层遗址，我的研究有助于建立一个控制加拿大和世界其他地区地震周期的通用模型。