Collaborative Research: the role of fluids in intermediate-depth seismicity and wedge anisotropy: Case studies for Cascadia and Alaska, with a comparison to Japan

合作研究：流体在中深度地震活动和楔形各向异性中的作用：卡斯卡迪亚和阿拉斯加的案例研究，并与日本进行比较

• 批准号: 1249486
• 负责人: Bradley Hacker
• 金额: $ 7.55万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1249486&HistoricalAwards=false
• 关键词: Collaborative; Research; role; fluids; intermediate

The main goal of this study is to determine whether the presence of fluids within Earth's mantle is a controlling factor determining where earthquakes occur within subduction zones, specifically along the fault that enables the down-going tectonic plate to slip deeper into surrounding viscous mantle. The fact that this seismicity is located within the crust at 'cool' subduction zones, such as Alaska and Tohoku, versus in the mantle at 'warm' subduction zones, such as Cascadia and Nankai, suggests that fluids play an important role. Directional dependence of seismic wave propagation speeds will be assessed, so that possible bias in earthquake locations can be accounted for. Simultaneously, information about deformation within the viscously flowing mantle will be obtained. Ratios of shear and compressional wave velocities will suggest where fluids are present or not. These constraints will guide computer modeling of mantle flow and temperature in the subduction zones. These results will be linked to petrologic models of mineral phase change associated with plate dehydration that introduce fluids near the plate interface and lead to the generation of arc volcanism. In-depth collaboration by three geoscientists- a geodynamist, petrologist, and seismologist, serves as a model of interdisciplinary Earth System research. Graduate and undergraduate students will receive training in the use of state-of-the-art methods in their sub-discipline as well as learning how to address interplay with evolving results from complementary sub disciplines. The international collaboration with Japanese scientists provides access to the best instrumented and well-studied Japanese subduction system. The study leverages ongoing work in the NSF GeoPRISMS and EarthScope Programs at Cascadia and that planned for Alaska.

这项研究的主要目的是确定地球地幔中流体的存在是否是确定俯冲带内地震发生的控制因素，特别是沿断层，使下降的构造板可以更深地滑入周围的粘性地幔。这种地震性位于“凉爽”俯冲带（例如阿拉斯加和Tohoku）的地壳内，在“温暖”俯冲区（例如Cascadia和Nankai）的地幔中，这一事实表明，流体表明流体起着重要作用。将评估地震波传播速度的定向依赖性，以便可以考虑地震位置的偏见。同时，将获得有关粘性地幔中变形的信息。剪切和压缩波速度的比率将表明流体是否存在。这些限制将指导俯冲带中地幔流量和温度的计算机建模。这些结果将与与板脱水相关的矿物相变变的岩石学模型，该模型在板界面附近引入流体并导致弧火山的产生。三位地球科学家的深入合作 - 地球动力学家，岩石学家和地震学家，是跨学科地球系统研究的模型。研究生和本科生将在其子学科中使用最新方法的培训，并学习如何与互补子学科的不断发展的结果解决相互作用。与日本科学家的国际合作提供了对日本俯冲系统最佳仪器的访问权限。这项研究利用了卡斯卡迪亚的NSF地理位置和Earthscope计划的正在进行的工作，并计划为阿拉斯加进行。