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、山脉和高原的形成以及相关的地震活动的规律。该研究将集中在印度-亚洲碰撞的背景下。该研究小组将分析和模拟尼泊尔喜马拉雅山廓尔喀7.8级地震后的变形。他们还将利用自末次冰期以来的湖平面变化来更好地了解该地区的总体变形。这一主题在地质学和地球动力学方面具有广泛的意义：它将有助于了解大陆如何因地形、水文或冰川作用而支撑表面载荷;它还对喜马拉雅-西藏地区的地震危险具有影响。这项工作将与尼泊尔的科学家合作，并将与国家地震技术协会合作，更新尼泊尔的建筑法规。该项目将资助一名研究生和一名博士后研究员。该研究将推进我们对大陆变形力学和喜马拉雅前缘沿着地震周期的理解。这项工作将模拟尼泊尔喜马拉雅山Mw7.8 Gorkha地震后的震后变形。这种分析将通知故障摩擦法和粘弹性特性负责短期震后松弛。它们基于地表变形对大陆水文引起的载荷变化的响应，限制了地壳和上地幔的粘性。他们利用全新世时间尺度对湖平面变化的响应，利用古海岸线的变形，以及现代十年时间尺度，以及通过分析对现代湖平面变化的响应和GRACE测量的表面负荷的长波长变化的十年时间尺度。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与温度相关的非线性粘性流动定律以及可能需要的瞬时粘性流变学。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.