Collaborative research: Cascadia2020: Investigating subduction zone segmentation with a 3D high-resolution Vp model

合作研究：Cascadia2020：使用 3D 高分辨率 Vp 模型研究俯冲带分割

• 批准号: 1946426
• 负责人: Emilie Hooft Toomey
• 金额: $ 27.8万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1946426&HistoricalAwards=false
• 关键词: Collaborative; research; Cascadia2020; Investigating; subduction

The Cascadia subduction zone is known to generate infrequent (every ~500 years) but potentially very large (up to magnitude 9) earthquakes. The most recent such earthquake occurred on January 26th, 1700, and GPS data acquired during the last two decades suggest that strain is accumulating across the subduction zone fault in preparation for a future earthquake. However, there is considerable uncertainty about how the geologic structure of the subduction zone will impact strain release during a Cascadia earthquake. Different plausible earthquake scenarios result in quite different predicted ground shaking, which in turn influences building codes and emergency response plans. This project will image the structure of the crust in the region where large Cascadia earthquakes are thought to occur. The objective is to understand three-dimensional variations in seismic velocity in order to provide insights into the factors that control segmentation of slip during earthquakes and the resulting amplitude of ground shaking in populated areas and sedimentary basins. With its large footprint and involvement of many field hands, this project will provide student research experiences and opportunities for public outreach and education about geohazards in the Pacific Northwest. This project is a collaboration between Oregon State University, University of Oregon, Eugene, South Dakota School of Mines and Technology and the U.S. Geological Survey.This project has the ultimate goal of generating a high-resolution model of an active subduction system that will span the Cascadia plate boundary, including the transition between major along-strike segments, and cross the transition from the nominally locked zone down-dip to depths where plate motion is accommodated by episodic tremor and slip. A dense network of temporary short-period seismometers along the coast of the Pacific Northwest will extend high resolution imaging of the structure of the overlying and down-going plates, as well as the thickness and characteristics of material within the plate interface zone, to depths that are critical for understanding earthquake processes. The array design includes a single deployment of three-component instruments at 1-km intervals along the onshore extension of dip lines embedded within a sparser grid of seismometers spaced 7-10 km apart for a total of ~700 three-component seismic stations. To tie results from the seismogenic part of the plate boundary to larger-scale forearc and arc structure, two profiles will extend across the forearc. All stations will record natural sources as well as man-made sources for the duration of the deployment. The seismic data from this experiment will be made immediately available to the community. The resulting high-resolution 3D Vp model will also be made accessible and is critical for constraining analyses of seismic noise, magnetotelluric and potential field data, as well as for improving predictions of earthquake ground shaking and tsunami generation in the Pacific Northwest.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

已知Cascadia俯冲带会产生很少（每500年），但可能非常大（9级）地震。最新的地震发生在1700年1月26日，在过去的二十年中获得的GPS数据表明，菌株正在俯冲带跨俯冲区断层积聚，以准备未来的地震。但是，关于俯冲带的地质结构将如何影响卡斯卡迪亚地震期间的应变释放存在很大的不确定性。不同合理的地震场景导致完全不同的预测地面摇动，这反过来又影响了建筑法规和应急响应计划。该项目将在认为发生大型卡斯卡迪亚地震的地区图像地壳的结构。目的是了解地震速度的三维变化，以便深入了解控制地震期间滑动分割的因素以及人口稠密地区和沉积盆地的地面震动幅度。该项目凭借许多野外手的占地面积和参与，将为Pacific Northwest的Geohazards公共宣传和教育提供学生的研究经验和机会。 This project is a collaboration between Oregon State University, University of Oregon, Eugene, South Dakota School of Mines and Technology and the U.S. Geological Survey.This project has the ultimate goal of generating a high-resolution model of an active subduction system that will span the Cascadia plate boundary, including the transition between major along-strike segments, and cross the transition from the nominally locked zone down-dip to depths where plate motion is accommodated by情节震颤和滑倒。沿太平洋西北海岸的临时短期地震仪的密集网络将扩展对上层和下层板的结构的高分辨率成像，以及板界面区域内材料的厚度和特征，到了解地震过程至关重要的深度。阵列设计包括沿着嵌入在间隔7-10 km的稀疏地震仪中嵌入的倾斜线的倾斜线沿岸延伸的沿海沿岸延伸，总计约700个三组分地震站，沿着浸入较稀疏的地震仪的斜线延伸，以1公里的间隔部署三组分仪器的单个部署。为了将板边界的地震部分与大规模前臂和弧形结构联系起来，两个轮廓将延伸到前臂。在部署期间，所有电台都将记录自然来源以及人为的来源。该实验的地震数据将立即提供给社区。由此产生的高分辨率3D VP模型也将可以访问，对于约束地震噪声，磁性和潜在的现场数据的分析以及改善地震地面摇晃和海啸的预测的分析至关重要，这反映了NSF的法定任务和Intelliation的支持。