RAPID: Collaborative Research: Subduction zone imaging following the 2018 Anchorage earthquake

RAPID：合作研究：2018 年安克雷奇地震后的俯冲带成像

• 批准号: 1917368
• 负责人: Kevin Ward
• 金额: $ 0.61万
• 依托单位: South Dakota School of Mines and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-15 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1917368&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Subduction; zone

Subduction zones are places on Earth where one plate goes beneath another plate. They are responsible for numerous volcanic eruptions and earthquakes, as the recent Anchorage earthquake. Important dynamical processes take place in between the two converging plates, such as the buoyant rising of molten mantle rock below volcanoes. Seismology offers a direct way to image the convective zones of subduction, which are between 30 km and 200 km deep. Seismometers installed in the field record seismic waves from earthquakes occurring in the down going plate and all over the world. By modeling the wave forms and timing, using techniques like those used in medical ultrasound imaging, images of the subduction zone can be obtained. Here, the project team will install more than 300 seismometers above the Alaska subduction zone. It will take advantage of the seismic waves produced by the ongoing aftershocks from the Anchorage earthquake to image at high resolution the subsurface structures. This project will also test the imaging capabilities of the timely deployment of dense networks of small seismometers, a new approach in seismology. It will provide critical constraints for models of subduction zone dynamics and associated hazards, as well as field experience to seven students in seismology. This RAPID project will support the deployment of 306 seismometers (three-component nodal sensors) to image the Alaska subduction zone at an unprecedented resolution. It will take advantage of the active local seismicity enhanced by the aftershocks of the 2018 magnitude-7 Anchorage earthquake. Recent results from Cascadia indicate that ambient noise and teleseism body waves can be used to image crustal structure. Here, local seismicity will be used to image the mantle wedge and crustal structure. Distant earthquakes will be used to image subsurface discontinuities, such as the crustal thickness and the subducting slab. Surface waves from ambient noise will be used to characterize the shallow crustal structure. This should allow resolving at km-scale the structural complexity within the mantle wedge between the subducting Pacific plate and the overlying North American crust. Furthermore, by leveraging an ongoing smaller-scale project focused on the Denali fault, this work will allow the simultaneous characterization of small-scale fault zone structures and broader crustal contrasts across the fault. Higher resolution images will provide important constraints for models seeking to understand the dynamics of subduction zones. The project is led by three early-career scientists and will involve seven students in seismology for the field deployment and recovery.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.

俯冲带是地球上一个板块进入另一个板块下方的地方。它们造成了许多火山爆发和地震，例如最近的安克雷奇地震。重要的动力学过程发生在两个聚合板块之间，例如火山下方熔融地幔岩石的浮力上升。地震学提供了一种直接的方法来对俯冲对流带进行成像，俯冲带的深度在 30 公里到 200 公里之间。安装在现场的地震仪记录下沉板块和世界各地发生的地震的地震波。通过对波形和时间进行建模，使用医学超声成像中使用的技术，可以获得俯冲带的图像。在这里，项目团队将在阿拉斯加俯冲带上方安装300多个地震仪。它将利用安克雷奇地震持续余震产生的地震波对地下结构进行高分辨率成像。该项目还将测试及时部署小型地震仪密集网络的成像能力，这是地震学的一种新方法。它将为俯冲带动力学和相关灾害模型提供关键约束，并为七名地震学学生提供现场经验。该 RAPID 项目将支持部署 306 个地震仪（三分量节点传感器），以前所未有的分辨率对阿拉斯加俯冲带进行成像。 它将利用2018年安克雷奇7级地震余震增强的当地活跃地震活动。卡斯卡迪亚的最新结果表明，环境噪声和远震体波可用于对地壳结构进行成像。在这里，局部地震活动将用于对地幔楔和地壳结构进行成像。远程地震将用于对地下不连续性进行成像，例如地壳厚度和俯冲板片。来自环境噪声的表面波将用于表征浅层地壳结构。这应该能够在公里尺度上解决俯冲太平洋板块和上覆北美地壳之间的地幔楔内的结构复杂性。此外，通过利用正在进行的专注于德纳利断层的小型项目，这项工作将能够同时表征小规模断层带结构和断层上更广泛的地壳对比。更高分辨率的图像将为寻求了解俯冲带动态的模型提供重要的约束。该项目由三名早期职业科学家领导，将涉及七名地震学学生进行现场部署和恢复。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。