Reducing risk from crustal earthquakes in western Canada

降低加拿大西部地壳地震的风险

• 批准号: 312429-2009
• 负责人: Cassidy, John
• 金额: $ 1.65万
• 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: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=571743
• 关键词: Reducing; risk; crustal; earthquakes; western

Western Canada is subject to the greatest seismic hazard in Canada. Some of the world's largest earthquakes have occurred in this region, including the magnitude (M) 9 Cascadia subduction earthquake to the west of Vancouver Island in 1700; the M=8.1 earthquake just to the west of the Queen Charlotte Islands in 1949; and the M=7.9 Denali Fault earthquake in Alaska, which ruptured to within 100 km of the Yukon border. Other large, damaging crustal earthquakes include the 1918 M=7 event and the 1946 M=7.3 event, both on Vancouver Island, and the M=7 earthquake just south of the Fraser Valley in 1872. These crustal earthquakes pose a threat to the population centres of southwest BC, and also to critical infrastructure throughout western Canada, including pipelines in the Yukon and NWT, hydroelectric dams and transmission infrastructure throughout western Canada, and port facilities in BC. The importance of understanding crustal earthquakes was demonstrated by the M=6.9 Kobe, Japan earthquake that caused more than $300B dollars in damage. However, crustal earthquakes in western Canada are enigmatic. There are large-scale crustal faults, such as the Denali Fault, Tintina Fault, and Fraser Fault - however no significant amount of seismicity has been observed on these structures during historic times. In southwestern BC, where large crustal earthquakes have occurred (e.g., 1946 central Vancouver Island) - there is no evidence for surface faulting, and so the "active fault" may be hidden at depth. The long-term goal of this proposed research is to better understand crustal earthquakes in western Canada - where can they occur, how large can they be, how often might they occur, and how will the ground shake. We will do this by identifying active structures, mapping the slip distribution and rupture process along faults, and mapping the earthquake-generating stress field. The results of these studies will be incorporated into seismic hazard maps in the National Building Code of Canada, and will provide waveforms useful for engineering applications. This, in turn, will help to minimise losses and economic impact of future earthquakes in this region. The benefits to society from this type of research can be in the billions of dollars.

加拿大西部是加拿大地震灾害最严重的地区。一些世界上最大的地震都发生在该地区，包括 1700 年温哥华岛西部发生的 9 级卡斯卡迪亚俯冲地震； 1949 年，夏洛特皇后群岛西部发生了 8.1 级地震；阿拉斯加州发生的里氏7.9级德纳利断层地震，地震破裂至育空地区边界100公里以内。其他破坏性大的地壳地震包括 1918 年发生在温哥华岛的 7 级地震和 1946 年发生的 7.3 级地震，以及 1872 年在弗雷泽河谷以南发生的 7 级地震。这些地壳地震对人口构成威胁不列颠哥伦比亚省西南部的中心，以及整个加拿大西部的关键基础设施，包括育空地区和西北地区的管道、整个加拿大西部的水力发电大坝和输电基础设施以及不列颠哥伦比亚省的港口设施。日本神户 M=6.9 级地震造成了超过 300B 美元的损失，这证明了了解地壳地震的重要性。然而，加拿大西部的地壳地震却很神秘。这里有大规模的地壳断层，例如德纳利断层、廷蒂纳断层和弗雷泽断层，但在历史时期并未在这些结构上观察到大量的地震活动。在不列颠哥伦比亚省西南部，曾发生过大地壳地震的地方（例如1946年的温哥华岛中部）——没有证据表明存在地表断层，因此“活动断层”可能隐藏在深处。这项研究的长期目标是更好地了解加拿大西部的地壳地震——它们会在哪里发生、震级有多大、发生的频率以及地面将如何震动。我们将通过识别活动结构、绘制沿断层的滑移分布和破裂过程以及绘制地震产生应力场来实现这一目标。这些研究的结果将被纳入加拿大国家建筑规范的地震灾害图中，并将提供对工程应用有用的波形。反过来，这将有助于最大限度地减少该地区未来地震的损失和经济影响。此类研究给社会带来的效益可达数十亿美元。