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

这个项目将研究控制大陆如何变形、山脉和高原的形成以及相关的地震活动的规律。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地区7.8级廓尔喀地震后的变形。他们还将利用末次冰期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兴趣：它将有助于理解大陆是如何由于地形、水文或冰川作用而支撑地表负荷的；这对喜马拉雅山-西藏地区的地震灾害也有影响。这项工作将与尼泊尔的科学家合作，并将与尼泊尔国家地震技术学会合作，更新尼泊尔的建筑规范。该项目将资助一名研究生和一名博士后。这项研究将促进我们对大陆变形机制和喜马拉雅锋面地震旋回的认识。这项工作将模拟尼泊尔喜马拉雅地区7.8级廓尔喀地震后的震后变形。这一分析将为断层摩擦规律和负责震后短期松弛的粘弹性特性提供信息。它们约束了地壳和上地幔的黏性，这是基于大陆水文引起的载荷变化对地表变形的响应。他们利用全新世时间尺度上对湖泊水位变化的响应，利用古海岸线的变形和现代年代际时间尺度，以及在年代际时间尺度上，通过分析对现代湖泊水位变化的响应和对GRACE测量的地表负荷长波变化的响应。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非线性粘性流动规律，以及对瞬态粘性流变学的可能需求。该奖项反映了美国国家科学基金会的法定使命，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.