Geodynamics and earthquakes in subduction zones and lithosphere

通过这份申请，我希望在未来五年内的任何一年都能获得两到三名研究生的部分资助。建议的基础研究主要集中在俯冲带的地震过程上。预计来自威胁加拿大西海岸的卡斯卡迪亚俯冲带的“大地震”是一个离家近的例子，说明了这项研究的社会相关性。学生们将学习是什么控制了大逆冲断裂的下倾延伸，浅层断裂如何导致海啸的产生，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的发生，构造载荷如何控制俯冲带和岩石圈的应力状态，什么样的应力和结构环境会导致地震，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察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。未来5年，我们将从三个方面开展研究，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。第一个方向是关于地壳如何为下一次地震积累能量。这个过程在前一次地震之后开始，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，并提高对变形过程的理解。这些结果将指导使用当代地壳变形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深度达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。我们还将研究巨型逆冲断层浅部的断裂如何使海底变形从而产生海啸。无论是浅层还是深层，我们都对传统观念提出质疑，力求发展新的理论。研究结果将有助于评估地震和海啸灾害以及设计早期预警系统。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。这些结果将对地震发生的机理产生新的认识，并指导今后将长期构造与地震灾害联系起来的研究。

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.