Geodynamics and earthquakes in subduction zones and lithosphere

俯冲带和岩石圈的地球动力学和地震

• 批准号: RGPIN-2022-03861
• 负责人: Wang, Kelin
• 金额: $ 3.13万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750987
• 关键词: Geodynamics; earthquakes; subduction; zones; lithosphere

With this application, I seek funds to provide partial support for two to three graduate students at any given year over the next five years. The proposed fundamental research is focused mainly on earthquake processes in subduction zones. The anticipated "big one" from the Cascadia subduction zone that threatens Canada's west coast is a near-home example to exemplify the societal relevance of the research. The students will study what controls the downdip extension of megathrust rupture, how shallow rupture contributes to tsunami generation, how the viscoelastic behaviour of Earth's mantle controls earthquake cycles, what crustal deformation observed today tells us about the next earthquake, how tectonic loading governs the state of stress in subduction zones and the lithosphere, what stress and structural environments enable earthquakes, and so forth. Our main method is to use computer modelling to explain global multidisciplinary observations to reveal underlying physical principles. The students are directed to develop geodynamic concepts from large volumes of observations and basic principles, not merely from textbooks and conventional models. With the long-term objective of understand the geodynamics of convergent margins and its larger tectonic environment, we will conduct research in three directions over the next five years. The first direction is about how the Earth's crust builds up energy for the next earthquake. The process begins right after the previous earthquake and proceeds in a complex fashion towards the next earthquake. It is controlled by the viscoelastic behaviour of the mantle. We will develop new viscoelastic earthquake cycle models and gain improved understanding of the deformation process. The results will guide the use of contemporary crustal deformation observations to evaluate seismic potential. The second direction is about earthquake rupture itself. We will study what enables or stops megathrust rupture to depths as large as 50 km or greater, factors including temperature and fault zone material. We will also study how the rupture of the shallow end of the megathrust deforms the seafloor to generate tsunamis. For both the shallow and deep parts, we question conventional concepts and aim to develop new theories. The results will contribute to the assessment of seismic and tsunami hazards and the design of early warning systems. The third direction is about how tectonic forces cause earthquakes. We will study the state of stress in subduction zones and the lithosphere, including investigating a paradox regarding earthquake occurrence under seemingly very low stresses. The results will yield new understanding of the mechanics of earthquake generation and guide future research in linking long-term tectonics to earthquake hazards.

有了这个应用程序，我寻求资金提供部分支持两到三个研究生在任何给定的一年在未来五年。拟议的基础研究主要集中在俯冲带的地震过程。来自威胁加拿大西海岸的卡斯卡迪亚俯冲带的预期“大地震”是一个接近家庭的例子，以证明这项研究的社会相关性。学生们将研究是什么控制了巨型逆冲断层的下倾延伸，浅破裂如何有助于海啸的产生，地幔的粘弹性行为如何控制地震周期，今天观察到的地壳变形如何告诉我们下一次地震，构造载荷如何控制俯冲带和岩石圈的应力状态，什么应力和结构环境使地震发生，等等。我们的主要方法是使用计算机建模来解释全球多学科观测，以揭示潜在的物理原理。指导学生从大量的观测和基本原理中发展地球动力学概念，而不仅仅是从教科书和传统模型中。以了解会聚边缘的地球动力学及其更大的构造环境为长期目标，我们将在未来五年内从三个方向进行研究。第一个方向是关于地壳如何为下一次地震积累能量。这一过程在前一次地震后立即开始，并以复杂的方式进行到下一次地震。它是由地幔的粘弹性行为控制的。我们将开发新的粘弹性地震周期模型，并获得更好的理解变形过程。其结果将指导使用当代地壳形变观测来评估地震潜力。第二个方向是关于地震破裂本身。我们将研究是什么促使或阻止了50公里或更深的巨型逆冲断层破裂，包括温度和断层带物质在内的因素。我们还将研究大型逆冲断层浅端的破裂如何使海底变形以产生海啸。对于浅层和深层的部分，我们质疑传统的概念，并旨在发展新的理论。研究结果将有助于评估地震和海啸灾害以及设计预警系统。第三个方向是关于构造力如何引起地震。我们将研究俯冲带和岩石圈的应力状态，包括调查在看似非常低的应力下发生地震的悖论。这些结果将产生对地震生成机制的新认识，并指导未来将长期构造与地震灾害联系起来的研究。