Subduction zone seismic hazards, oceanic crust evolution and paleoclimate reconstruction

拟议的工作将调查影响我们社会的自然现象。该提案的重点是研究俯冲和实验室内地震，以及与之相关的地震危险。俯冲地震和陆内地震都是俯冲带所特有的，俯冲带是大洋板块下沉或俯冲到大陆板块之下的俯冲区域。俯冲地震，发生在板块间的界面上，是地球上最大的地震（震级>8-9级）。板块内地震发生在俯冲洋板块内，震级可达7-8级。俯冲带地震对沿海社区构成巨大威胁，2004年苏门答腊9.3级大地震和随后造成数十万人死亡的海啸就是一个悲剧。该项目将测试地震反射成像在广角折射工作、热模拟结果和地震活动数据的支持下是否可用于俯冲地震破裂区的高分辨率绘图。将使用同样的方法来确定渗透深度和俯冲板块中储存的水量与观测到的实验室内地震活动的频率和最大震级之间的关系。预期结果（例如，俯冲地震破裂的向陆极限和卡斯卡迪亚边缘的最大地震震级）应提供改进地震危险概率图所需的限制。像这样的项目对加拿大和加拿大人来说很重要，因为北方卡斯卡迪亚俯冲带位于加拿大西部近海。拟议的研究还将侧重于使用地面穿透雷达对沙丘的内部几何形状进行成像，并研究它们如何随着时间的推移而演变。沙丘对气候变化非常敏感，是过去气候条件的宝贵档案。探地雷达图像将与遥感、地质年代学测年和地貌制图结果一起进行分析，目的是重建负责形成所调查沙丘的晚第四纪当地古气候。最近的气候变化引起了公众的极大兴趣。

The proposed work will investigate natural phenomena that impact our society. The thrust of the proposal is focused on studying subduction and intraslab earthquakes, and the seismic hazards associated with them. Both subduction and intraslab earthquakes are unique to subduction zones, regions of underthrusting where the oceanic plates dip or subduct underneath the continental plates. Subduction earthquakes, generated on the interplate interface, are the largest earthquakes on Earth (magnitudes >8-9). Intraslab earthquakes are generated within subducting oceanic plate and have magnitudes that can be >7-8. Subduction zone earthquakes pose a huge threat to coastal communities as was tragically illustrated in 2004 by the giant magnitude 9.3 Sumatra earthquake and the subsequent tsunami that killed hundreds of thousands of people. This project will test if seismic reflection imaging, supported by wide-angle refraction work, thermal modeling results and seismicity data, can be used for high-resolution mapping of subduction earthquake rupture areas. The same methodology will be used to determine the relationship between the depth of penetration and volume of water stored in the subducting plates, and the observed frequency and maximum magnitude of intraslab seismicity. The anticipated results (e.g., landward limit of subduction earthquake rupture and maximum magnitude of intraslab earthquakes at the Cascadia margin) should provide constraints needed for improved probabilistic seismic hazards maps. Projects like this are important to Canada and Canadians because the northern Cascadia subduction zone is located offshore western Canada. The proposed research will also focus on using ground penetrating radar to image the internal geometry of sand dunes and to study how they evolve through time. Sand dunes are highly sensitive to climate variability and represent valuable archives of past climatic conditions. Ground penetrating radar images will be analyzed together with remote sensing, geochronological dating, and geomorphic mapping results with the goal to reconstruct the Late Quaternary local paleoclimate responsible for the formation of the investigated sand dunes. Recent climate change is of great public interest.