Numerical models of faulting and plate boundary deformation

在接下来的五年里，我在UBC的研究小组将继续研究脆性上地壳下的断层是如何工作的。我们的主要目标是解释断裂带是如何将构造板块的稳定相对运动与脆性上地壳断层上的间歇性地震联系起来的。如果我们能理解这一点，我们就能估计断层上的力，并计算破坏性地震的概率。为了进行研究，我们开发了代表主要断层系统的数值计算机模型，以及它们所处的岩石圈。我们测试我们是否可以建立一个足够精确的模型来复制来自地球的数据——例如，对地球表面断层周围运动的超精确GPS测量。一些模型假设，一层“粘稠”物质将断层与地幔连接起来，构造板块沿着这一表面相互滑动。其他模型假设，在脆弱的上地壳之下的一切（在活动断层数百公里内）都可以流动，所以构造板块实际上只是脆弱的上地壳。还有许多其他的想法需要测试。我的团队开发了圣安德烈亚斯断层、卡斯卡迪亚俯冲带和土耳其断层周围的变形模型，这些断层导致了1999年伊兹米特的致命地震。对于每一个错误，我们都开发了一个主模型，它代表了我们关于它如何工作的最佳假设。了解断层的工作原理对于全面解释板块构造是至关重要的，但这也是计算绝对地壳应力以及这些应力如何随时间变化的先决条件。两者都需要进行精确的基于物理的地震危险评估。

During the next five years, my research group at UBC will continue to investigate how faults work below the brittle upper crust.  Our main goal is to explain how fault zones connect the steady relative moton of tectonic plates to episodic earthquakes along faults in the brittle upper crust. If we can understand this, we can estimate forces along faults, and calculate the probability of damaging earthquakes.To do our research, we develop numerical computer models that represent major fault systems, and the lithosphere in which they are embedded.  We test whether we can make a model accurate enough to reproduce data from the Earth - for example, ultra-precise GPS measurements of motion of the Earth's surface around faults.  Some models assume that a plane of 'gooey' material connects the fault to the mantle and the tectonic plates slide past each other along this surface.  Other models hypothesize that everything below the brittle upper crust (within hundreds of kilometers of an active fault) can flow, so the tectonic plate is actually just the brittle upper crust.  There are many other ideas to test as well.My group develops models of deformation around the San Andreas fault, the Cascadia Subduction Zone, and the fault in Turkey that produced the deadly 1999 Izmit earthquake.  For each of these faults, we develop a master model which represents our best possible hypothesis about how it works. Understanding how faults work is fundamentally important for fully explaining plate tectonics, but it is also a prerequisite for calculating absolute crustal stresses and how these stresses vary with time.  Both are required for doing accurate physics-based seismic hazard assessments.