Probing the mechanical properties of the crust and upper mantle in the Himalaya and Southern Tibet region

该项目将研究大陆如何变形、建造山脉和高原以及与之相关的地震活动的规律。这项研究将集中在印度-亚洲碰撞的背景下。研究小组将对尼泊尔喜马拉雅7.8级高尔卡地震后的形变进行分析和建模。他们还将利用自上一次冰川以来的湖泊水位变化来更好地了解该地区的总变形。这一主题在地质学和地球动力学中具有广泛的意义：它将有助于理解大陆如何支持由于地形、水文或冰川而产生的地表负荷；它也对喜马拉雅-西藏地区的地震灾害有影响。这项工作将与尼泊尔的科学家合作，并将与国家地震技术学会合作，更新尼泊尔的建筑规范。该项目将支持一名研究生和博士后研究员。这项研究将促进我们对喜马拉雅前缘大陆形变和地震旋回的理解。这项工作将模拟尼泊尔喜马拉雅Mw7.8 Gorkha地震后的震后变形。这一分析将揭示断层摩擦规律和导致短期震后松弛的粘弹性性质。它们基于地表变形对大陆水文引起的载荷变化的响应，约束了地壳和上地幔的粘性性质。他们使用全新世时间尺度上的湖平面变化的响应，使用古海岸线的变形和现代十年时间尺度，以及通过分析GRACE测量的现代湖泊水位变化和地表负荷的长波长变化的响应来使用十年时间尺度上的响应。这些研究将深入了解断层摩擦特性，控制地壳和上地幔分布变形的温度相关的非线性粘性流动规律，以及可能需要瞬时粘性流变学。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project will investigate the laws that govern how continents deform, build mountain ranges and plateaux and the associated seismicity. The research will focus on the context of the India-Asia collision. The research team will analyse and model deformation that followed the Mw 7.8 Gorkha earthquake in the Himalaya of Nepal. They will also use lake level variations since the last glaciations to better understand the total deformation of the region. This topic is of broad interest in geology and geodynamics: it will help understand how continents support surface loads due to the topography, hydrology or glaciations; it also has implications for seismic hazard in the Himalaya-Tibet region. The work will collaborative effort with scientists in Nepal and will work with the National Society of Earthquake Technology to update building code in Nepal. The project will support a graduate students and postdoctoral fellow.The research will advance our understanding of the mechanics of continental deformation and the seismic cycle along the Himalayan front. The work will model postseismic deformation following the Mw7.8 Gorkha earthquake in the Himalaya of Nepal. This analysis will inform fault friction laws and viscoelastic properties responsible for short-term post-seismic relaxation. They constrain the viscous properties of the crust and upper mantle based on the surface deformation response to load variations induced by continental hydrology. They use the response to lake level variations at the Holocene time scale, using the deformation of paleoshorelines, and modern decadal time scales, as well as at the decadal time scale by analysing the response to modern lake level variations and to long-wavelength variations of surface loads measured by GRACE. These investigations will give insight on fault frictional properties, the temperature-dependent non-linear viscous flow laws governing distributed deformation of the crust and upper mantle and the possible need for a transient viscous rheology.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.