Use GNSS to investigate the Present-day Tectonic Deformation in Western Canada

使用 GNSS 调查加拿大西部当今的构造变形

• 批准号: RGPIN-2022-04724
• 负责人: Jiang, Yan
• 金额: $ 1.89万
• 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=750976
• 关键词: Use; GNSS; investigate; Present; day

Contrary to the well-studied Cascadia Subduction Zone, crustal deformation in the Canadian Cordillera and its relation to the earthquake is not well understood. For example, GPS observations show that Puget Sound is a zone of northward-directed crustal compression (shortening) and seismicity. However, the existing crustal motion model does not show in detail how the pattern of deformation extends north into the Fraser Lowland and Vancouver, a region of high development and population density. The current lack of understanding of the deformation adds considerable uncertainty to the hazard model in Western Canada. An improved understanding of the present-day tectonics contributes to a better seismic hazard model, which is incorporated into residential building codes and the building codes of critical infrastructure (dams, power facilities, LNG plants), which will reduce risk and increase societal resilience. We will measure and model large-scale tectonic motions in Western Canada, focusing mainly on the Southern Canadian Cordillera, covering most of British Columbia and the nearby population centers in Alberta, such as Calgary and Edmonton. This model divides the elastic lithosphere into small blocks, assuming that the blocks are bounded by block boundary faults. The observed crustal deformation rate is assumed to be the sum of the rigid block rotation rate and elastic deformation rate due to the coupling of the block boundary faults. The block motion model has been successfully applied in the Western US and Alaska to explain the observed deformation field and seismicity, considering the elastic deformation caused by slip deficit at the subducting plate, rigid rotation, and coupling on the inland faults. However, a block model covering the entire Western Canada currently does not exist due to a sparse GNSS network coverage in the past. An increased number of newly installed continuous Global Navigation Satellite System (GNSS) stations improves the data coverage in the southern Cordillera. In addition, episodic GNSS sites will be occupied to improve the density further. We will collect and process GNSS data using up-to-date hardware and software. Advanced time series processing techniques will be used to derive GNSS secular rate and the noise model for accurate velocity determination. We will combine the GNSS velocity field with geological and seismological data to define crustal blocks in Western Canada and calculate the bounding fault slip rates. The outputs will provide a unified velocity model and present-day crustal fault slip rates in Western Canada. Comparing the present-day fault slip rate with the geologically determined fault slip rate will provide insights into the tectonic history of the Cordillera. Such a GNSS-based kinematic block motion model provides critical constraints on the first-order deformation pattern and the possibility of future earthquakes on faults and improves our understanding of the crustal dynamics in the cordillera.

与研究得很好的卡斯卡迪亚俯冲带相反，加拿大科迪勒拉山脉的地壳变形及其与地震的关系还没有得到很好的了解。例如，全球定位系统的观测表明，普吉湾是一个向北地壳压缩（缩短）和地震活动的区域。然而，现有的地壳运动模型没有详细显示变形模式如何向北延伸到弗雷泽低地和温哥华，这是一个高度发展和人口密度的地区。目前缺乏了解的变形增加了相当大的不确定性，在加拿大西部的灾害模型。对当今构造的更好理解有助于建立更好的地震灾害模型，该模型被纳入住宅建筑规范和关键基础设施（水坝，电力设施，液化天然气工厂）的建筑规范，这将降低风险并提高社会复原力。我们将测量和模拟加拿大西部的大规模构造运动，主要集中在加拿大南部的科迪勒拉，覆盖大部分的不列颠哥伦比亚省和附近的人口中心在阿尔伯塔，如卡尔加里和埃德蒙顿。该模型将弹性岩石圈划分为若干小块体，并假定这些小块体以块体边界断层为界。假定观测到的地壳形变速率为刚性块体旋转速率与块体边界断层耦合引起的弹性形变速率之和。块体运动模型已成功地应用于美国西部和阿拉斯加，以解释观测到的变形场和地震活动，考虑到弹性变形所造成的滑动亏损在俯冲板块，刚性旋转，并耦合上的内陆断层。然而，由于过去GNSS网络覆盖稀疏，目前不存在覆盖整个加拿大西部的块模型。新安装的连续全球导航卫星系统台站数量的增加改善了科迪勒拉山脉南部的数据覆盖面。此外，还将占用间歇性全球导航卫星系统站点，以进一步提高密度。我们将使用最新的硬件和软件收集和处理GNSS数据。将使用先进的时间序列处理技术来推导全球导航卫星系统长期速率和噪声模型，以便准确地确定速度。我们将联合收割机的GNSS速度场与地质和地震数据相结合，以确定加拿大西部的地壳块体，并计算边界断层滑动速率。输出将提供一个统一的速度模型和现今的地壳断层滑动率在加拿大西部。将现今断层滑动速率与地质学确定的断层滑动速率进行比较，将有助于深入了解科迪勒拉山脉的构造历史。这样一个基于GNSS的运动学块体运动模型提供了一阶变形模式和未来地震的可能性断层的关键约束，提高了我们的理解在科迪勒拉地壳动力学。