Unravelling the complex tectonics of western and northwestern Canada using broadband seismic data

利用宽带地震数据揭示加拿大西部和西北部的复杂构造

• 批准号: RGPIN-2021-03700
• 负责人: Schaeffer, Andrew
• 金额: $ 2.19万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750983
• 关键词: Unravelling; complex; tectonics; western; northwestern

The objectives of my research program focus on outstanding questions relating to the evolution and dynamics of the solid Earth, in particular the crust and upper mantle associated with tectonically active regions. I approach these objectives through the application and development of detailed, 3D seismic velocity models of the onshore and offshore obtained using networks of broadband seismic instruments. The sophisticated processing and imaging tools, developed in house and with close collaborators, enable the extraction of maximum structural information from available seismic datasets, providing robust, statistically sound analysis and interpretation. Specifically, my research focuses on the actively deforming regions of western and northern Canada, as revealed through the lens of seismic velocity and associated physical properties, as well as the location and patterns of seismicity. Ultimately, these objectives will improve our assessment of earthquake and related hazards, and therefore mitigation procedures, as well as advancing deep mineral system knowledge across western and northern Canada. In western Canada, the North American continent is juxtaposed against a complex offshore tectonic system. This includes the Cascadia Subduction Zone in the south, where the Juan de Fuca and Gorda Plates are subducting beneath the margin. In the north, the transpressional Queen Charlotte Fault system extends from southern Haida Gwaii northwards to Alaska. In between these two plate boundary systems lies the Queen Charlotte Triple Junction, a complex area of small plates and plate fragments that accommodate this change in deformation style. This broad region on the BC coast is home to the highest seismic hazard in Canada and can slip in large (and sometimes giant) earthquakes. The Northern Canadian Cordillera (NCC) and southwest Canadian Arctic has been tectonically active for ~250 Myr and is host to numerous mineral and geothermal energy resources, as well as transportation and energy corridors vital to northern residents. This region is also home to significant seismicity, distributed broadly across the NCC and extending northwards off the Mackenzie Delta into the Beaufort Sea. As a result of continued climate warming, this northern region is particularly prone to mass wasting events and coastal erosion as a result of melting permafrost, making it more susceptible to ground shaking from local and regional earthquakes. In the proposed research, I plan to use all available seismic data within western and northern Canada to constrain these complex tectonic systems, including the Western Arctic Regional Network of Seismographs (WARNS), a network I deployed with colleagues. My long-term vision includes future off-shore deployments in several key areas, including the Beaufort Sea and Queen Charlotte Triple Junction, which will not only be highly complementary to this work, but capitalize on important opportunities for the Canadian geoscience community.

我的研究项目的目标集中在与固体地球的演化和动力学有关的突出问题上，特别是与构造活跃区域相关的地壳和上地幔。我通过应用和开发利用宽带地震仪器网络获得的陆地和海上详细的三维地震速度模型来实现这些目标。公司内部和密切合作开发了复杂的处理和成像工具，能够从可用的地震数据集中提取最大的结构信息，提供可靠的、统计上合理的分析和解释。具体来说，我的研究主要集中在加拿大西部和北部的积极变形地区，通过地震速度和相关的物理性质，以及地震活动的位置和模式的镜头揭示。最终，这些目标将改善我们对地震和相关危害的评估，从而改善减灾程序，并推进加拿大西部和北部深部矿物系统的知识。在加拿大西部，北美大陆与一个复杂的近海构造系统并列。这包括南部的卡斯卡迪亚俯冲带，胡安·德富卡板块和戈尔达板块在这里俯冲到边缘之下。在北部，逆断层的夏洛特女王断层系统从海达瓜伊南部向北延伸至阿拉斯加。在这两个板块边界系统之间是夏洛特女王三重交界处，这是一个由小板块和板块碎片组成的复杂区域，可以适应这种变形风格的变化。这片位于不列颠哥伦比亚省海岸的广阔地区是加拿大地震风险最高的地区，可能发生大型（有时是巨大）地震。加拿大北部科迪勒拉（NCC）和加拿大西南部北极地区的构造活动时间约为250迈，是众多矿产和地热能资源的所在地，也是对北部居民至关重要的交通和能源走廊。该地区也是重要地震活动的所在地，广泛分布在NCC，并从麦肯齐三角洲向北延伸到波弗特海。由于持续的气候变暖，这个北部地区特别容易发生大规模的浪费事件和永久冻土融化造成的海岸侵蚀，使其更容易受到当地和区域地震引起的地面震动的影响。在提议的研究中，我计划使用加拿大西部和北部所有可用的地震数据来约束这些复杂的构造系统，包括西北极地区地震仪网络（警告），这是我与同事部署的网络。我的长期愿景包括未来在几个关键地区的海上部署，包括波弗特海和夏洛特女王三重枢纽，这不仅是对这项工作的高度补充，而且是对加拿大地球科学界的重要机遇。