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: 1917446
• 负责人: Amir Allam
• 金额: $ 0.85万
• 依托单位: University of Utah
• 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=1917446&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Subduction; zone; 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.

俯冲带是地球上一块盘子在另一盘下方的地方。作为最近的锚地地震，他们负责许多火山喷发和地震。重要的动态过程发生在两个收敛板之间，例如火山下的熔融地幔岩石的浮力上升。地震学提供了一种直接的方式来形象俯冲的对流区域，该区域深30公里至200公里。野外记录中安装了地震仪的地震仪来自地震的地震波，发生在向下的板块和世界各地。通过对波形和时机进行建模，使用像医学超声成像中使用的技术一样，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区上方安装300多个地震米。它将利用从锚固地震到高分辨率地下结构的持续余震产生的地震波。该项目还将测试及时部署小型地震仪网络的成像功能，这是一种新的地震学方法。它将为俯冲区动态和相关危害的模型以及七个地震学学生的现场经验提供关键的限制。这个快速项目将支持在前所未有的分辨率下的306个地震米（三组分节点传感器）的部署，以对阿拉斯加俯冲带进行成像。 它将利用2018年7级锚固地震的余震增强的主动局部地震性。卡斯卡迪亚（Cascadia）的最新结果表明，环境噪声和远距离主义人体波可用于图像地壳结构。在这里，局部地震活动将用于对地幔楔形和地壳结构进行成像。遥远的地震将用于图像地下不连续性，例如地壳厚度和俯冲板。来自环境噪声的表面波将用于表征浅层地壳结构。这将允许在km尺度上解决俯冲太平洋板和上覆的北美地壳之间地幔楔内的结构复杂性。此外，通过利用一个持续的小规模项目，该项目的重点是Denali断层，这项工作将允许同时表征小规模断层区结构，并在整个断层上进行更广泛的地壳对比度。较高的分辨率图像将为寻求了解俯冲区的动态模型提供重要的限制。该项目由三位早期职业科学家领导，将涉及七名学生参与现场部署和恢复的地震学。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，认为值得通过评估来获得支持。