Geophysical studies of plate boundary zone processes in western North America and lithospheric structure of terrestrial planets

在接下来的五年里，我的研究计划将集中在地球物理学的两个关键问题上，一个是观测地震学，另一个是地球和类地行星岩石圈的流变学。第一个项目涉及北美西部主要板块边界带和断层周围的地壳和地幔结构，从加利福尼亚的圣安德烈亚斯断层到加拿大北部育空地区和西北地区的科迪勒拉，以及它们对地震和地壳变形的影响。许多不同类型的地震都发生在这个地区的主要断裂带上，每种地震都有自己的地震危险性。除了大型破坏性地震（如1906年圣阿德里亚斯地震或2011年日本东北大地震）外，这些断层还存在各种各样的滑动模式，包括最近发现的“慢滑动”和相关的“非火山震动”。虽然不是直接的威胁，但越来越多的证据表明，这些慢滑地震与常规地震的发生有关，通过断层的结构特性（例如，流体），如使用地震学数据成像。本研究旨在阐明这些构造属性在断裂和地震过程中的作用。第二个项目处理固体地球物理学中一个长期存在的问题，即地球和类地行星岩石圈的全球流变学和强度。固体地球对地质荷载（如冰盖、河流三角洲）的响应是由其刚度或长期强度决定的，这是通过比较地球引力场异常与地形而获得的。岩石圈强度的知识是了解地球和行星地壳演化和热输运的有用参数。在对用于估计这一参数的模型和技术进行重大修订之后，本研究将侧重于将新方法应用于地球和其他类地行星（如火星、金星、水星），以建立内太阳系行星流变学的分类。

Over the next five years my research program will focus on two key problems in geophysics, one in observational seismology and the other in the rheology of the lithosphere on Earth and terrestrial planets. The first project concerns the structure of the crust and mantle around major plate boundary zones and faults in western North America, from the San Andreas Fault in California to the northern Canadian Cordillera in the Yukon and Northwest Territories, and their influence on earthquake and crustal deformation. A number of different styles of earthquake, each with its own significance for seismic hazard, occur along major fault lines in this region. In addition to large destructive earthquakes (like the 1906 San Adreas earthquake or the 2011 Tohoku-Oki earthquake in Japan), these faults harbor a wide variety of slip modes, including the recently discovered "slow slip" and associated "non-volcanic tremors". Although not a direct threat, there is growing evidence that these slow slip earthquakes are associated with regular earthquake occurrence through structural properties (e.g., fluids) of the fault, as imaged using seismological data. This research aims to clarify the role played by such structural attributes in the faulting and earthquakes processes.The second project addresses a long-standing problem in solid-Earth geophysics, namely the global rheology and strength of the lithosphere of the Earth and terrestrial planets. The solid Earth's response to geological loads (e.g., ice sheets, river deltas) is determined by its rigidity, or long-term strength, which is obtained by comparing the Earth's gravitational field anomalies with the topography. Knowledge of lithospheric strength is a useful parameter to understand crustal evolution and heat transport in the Earth and planets. Following major revisions of models and techniques used to estimate this parameter, this research will focus on the application of the new methods to Earth and other terrestrial planets (e.g., Mars, Venus, Mercury) to establish a classification of planetary rheology for the inner solar system.