Collaborative Research: Anisotropy and Mantle Flow Beneath Japan from Seismological Observations and Geodynamical Modeling

合作研究：地震观测和地球动力学模拟的日本地下各向异性和地幔流

• 批准号: 0630494
• 负责人: Maarten de Hoop
• 金额: --
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-20 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0630494&HistoricalAwards=false
• 关键词: Collaborative; Research; Anisotropy; Mantle; Flow

Proper characterization of elastic anisotropy can help understand the causes, mechanisms, and consequences of tectonic deformation in the upper mantle and in other regions of the Earth's deep interior and beneath regions of active tectonics. Unfortunately, our understanding of seismic anisotropy is still unsatisfactory and interpretation of seismological diagnostics of anisotropy (such as shear wave birefringence) is often ambiguous. Gaining full understanding of seismic anisotropy and flow beneath complex tectonic regions has, therefore, remained an outstanding challenge of modern seismology and geodynamics. In collaboration with colleagues in France, scientists from MIT and Colorado School of Mines propose to meet this challenge through the explicit integration of powerful data sets and forward and inverse modeling tools. In particular, they aim to improve the understanding of 3-D seismic anisotropy and tectonic deformation in the upper mantle near subduction zones, which are tectonic regions that are of particular societal interest because of their association with significant volcanic and seismic hazard. They will focus on Japan, where geophysical instrumentation is dense because of the need for the continuous monitoring of seismic and volcanic activity.Data from these dense networks can be obtained through the internet, thanks to scientists in Japan, and the MIT-CSM team has already assembled a large data set from 64 broadband seismic stations. Through examination of ~12,000 individual seismograms, they compiled a database of ~1330 high-quality shear wave splitting measurements for S, SKS/SKKS, and ScS, and more will be added later. They propose to improve the quantitative interpretation of the splitting maps by combining two complementary approaches. First, they wish to extend their numerical modeling of upper mantle flow from 2.5 to 3-D, incorporating (evolving) velocity boundary conditions and realistic geometries and rheologies. Second, they plan to develop a novel technique for tomographic inversion of the observed shear wave polarizations and split times. The flow models will be used to design the parameterization and regularization of the inversion, and, in turn, the seismic imaging results will be used to update the flow models. Such an explicitly cross-disciplinary approach will not only yield new insight into the 3-D anisotropy and flow field beneath Japan. Indeed, the powerful new tools and concepts for data analysis, modeling, and interpretation can also be applied to data from such new initiatives as USArray/Earthscope.

弹性各向异性的适当表征可以帮助理解上地幔和地球深层内部以及主动构造区域以下的上地幔和其他区域中构造变形的原因，机制和后果。 不幸的是，我们对地震各向异性的理解仍然不令人满意，并且对各向异性的地震诊断（例如剪切波双折射）的解释通常是模棱两可的。 因此，对复杂构造区域下的地震各向异性和流动的全面了解仍然是现代地震学和地球动力学的杰出挑战。 与法国的同事合作，麻省理工学院和科罗拉多州矿业学院的科学家建议通过明确整合强大的数据集以及前进和反向建模工具来应对这一挑战。 特别是，它们旨在提高对俯冲带近地幔中3D地震各向异性和构造变形的理解，俯冲带近地幔，由于它们与重要的火山和地震危险相关，这是构造区域，特别是社会兴趣。 他们将重点关注日本，因为需要持续监测地震和火山活动，因此地球物理仪器是密集的。由于日本的科学家，可以通过互联网获得这些密集网络的数据，并且MIT-CSM团队已经组装了64个宽带地震站的大型数据。通过检查〜12,000个单独的地震图，它们为S，SKS/SKK和SCS和SCS的〜1330高质量剪切波分裂测量进行了编译，稍后将添加更多。 他们建议通过结合两种互补方法来改善分裂图的定量解释。 首先，他们希望将上地幔流量的数值建模从2.5扩展到3-D，并结合（不断发展的）速度边界条件以及现实的几何形状和流变。其次，他们计划开发一种新型技术，用于对观察到的剪切波极化和分裂时间的层析成像反转。 流模型将用于设计反转的参数化和正则化，然后，地震成像结果将用于更新流模型。 这种明确的跨学科方法不仅会对日本下面的3D各向异性和流场产生新的见解。 确实，用于数据分析，建模和解释的强大新工具和概念也可以应用于诸如USARRAY/EARTERSCOPE等新计划的数据。