Stress Transfer Between the Cascadia Megathrust and the Northern San Andreas Fault

从加利福尼亚湾到不列颠哥伦比亚省的北美西海岸是地震活动频繁的地区。大地震发生在加利福尼亚是众所周知的。鲜为人知的事实是，加州最北端、华盛顿州西部和俄勒冈州（卡斯卡迪亚边缘）经常遭受真正巨大的“巨型逆冲”地震，上一次发生在1700年左右。了解这些事件的频率，以及卡斯卡迪亚事件与发生在加州南部圣安德烈亚斯断层上的事件之间的联系是至关重要的。地震通常会在近海产生浊积岩（海底滑坡）沉积物。解决这些问题的一种方法是通过确定这些沉积物的年代来建立年表。该项目将沿着卡斯卡迪亚边缘获取新的岩心和浊积岩日期，以提高这一活动边缘环境下的高分辨率古地震年表，并测试两个板块边界断层系统之间相互作用的拟议模型。长期的古地震记录提供了进行这种比较的机会，测试了重复模型，并建立了行为和板块边界相互作用的长期记录，这是通常太短的地震记录所不可能做到的。这项工作的一个主要目的是测试一个假设，即沿着卡斯卡迪亚边缘的地震在全新世期间多次触发北圣安德烈亚斯断层的事件。这项工作更广泛的影响部分来自于这样一个事实，即卡斯卡迪亚边缘预计会产生真正巨大的“巨型逆冲”地震，伴随着海啸的危险，这项工作具有巨大的社会意义。这项工作将对美国和加拿大的地震和海啸灾害评估产生重大而直接的影响。其他好处是培养研究生和本科生参与项目。

The west coast of the North America from the Gulf of California to British Columbia is characterized by high earthquake activity. That great earthquakes occur in California is well known. Less well known is the fact that northernmost California, and western Washington and Oregon (the Cascadia Margin) are subject to truly great, "megathrust" earthquakes, the last of which occurred in about 1700. It is of vital importance to understand both the frequency of these events, and any linkage between events in Cascadia and those that occur to the south, on the San Andreas Fault in California. Earthquakes commonly produce turbidite (submarine landslide) deposits offshore. One way to address these issues is to establish chronologies by dating these deposits. This project will acquire new cores and date turbidites along the Cascadia Margin to improve high-resolution paleoseismic chronologies in this active margin setting and test a proposed model of interaction between two plate boundary fault systems. Long paleoseismic records afford the opportunity to make such comparisons, test models of recurrence, and establish long term records of behavior and plate boundary interaction that are not possible with earthquake records that are typically much too short. A primary aim of this work is to test the hypothesis that earthquakes along the Cascadia Margin have triggered events on the Northern San Andreas Fault repeatedly during the Holocene. Broader impacts of this work arise in part from the fact that the Cascadia Margin is expected to produce truly great "megathrust" earthquakes, with attendant tsunami hazards, this work has enormous societal relevance. This work should have a major, direct impact on the assessment of earthquake and tsunami hazards in the U.S. and Canada. Other benefits are training graduate students and the involvement of undergraduates in the project.