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断裂在脆弱的上地壳下是如何运作的。我们的主要目标是解释断裂带如何将构造板块的稳定相对运动与沿着脆弱上地壳的断层发生的幕式地震联系起来。如果我们能理解这一点，我们就可以估计沿着断层的力，并计算破坏地震的可能性。为了做我们的研究，我们开发数值计算机模型，代表主要的断层系统，以及它们所在的岩石圈。我们测试我们是否可以使一个模型足够准确，以复制来自地球的数据-例如，对地球表面围绕断层运动的超精密GPS测量。一些模型假设断层和地幔之间有一层粘稠的物质连接，构造板块沿着这个表面相互滑动。其他模型假设脆弱的上地壳(活动断裂数百公里范围内)下的一切都可以流动，因此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检验。我的团队开发了圣安德烈亚斯断层，卡斯卡迪亚俯冲带周围的变形模型，以及导致1999年伊兹米特致命地震的土耳其断层。对于这些断层中的每一个，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好的可能假设。了解断层如何工作对于全面解释板块构造至关重要，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。这两者都是进行准确的基于物理的地震危险性评估所必需的。

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.