Is the Tibetan Plateau Rising?

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。青藏高原是地球上最大的高地形区域。今天的青藏高原是不是越来越高了？印度继续与欧亚大陆碰撞，它是否由于持续的收缩而变得更高？它的坍缩是由于其过剩的引力势能驱动的伸展吗？它是否大致处于平衡状态，不再长高，而只是改变形状？高原的部分地区目前是否正在以不同的方式演变？这个项目是阿拉斯加大学和几个中国研究机构的研究人员共同努力的结果，旨在解决这些问题。来自青藏高原及其周边地区的全球定位系统（GPS）测量足够密集和精确，足以对西藏和印度-欧亚大陆碰撞带的其他地区的垂直运动进行有意义的测量。使用多年的GPS数据并在数据分析中仔细注意细节，即使在运动测量中也可以达到每年约1毫米的实际垂直测量精度。中国和印度-欧亚大陆碰撞带其他地区的数百个活动GPS站点现在有足够的数据来提供可靠的垂直速度估计。将使用下一代模型和轨道对这些数据进行完全重新分析，并将开发解释观测速率和空间变化的模型。将使用大面积的垂直速率，包括没有预期变形的区域，并通过将估计的全球定位系统垂直运动与重复水准测量和干涉合成孔径雷达的补充数据进行比较，来评估精度。这项研究将首先集中在一个壮观的活动构造区域的垂直运动的系统区域测量和建模。提高对地壳变形的认识将有助于更好地了解中国这个人口稠密、地震多发地区的地震危害。虽然本项目的重点是垂直运动，但我们也将获得更精确的水平运动估计，并且使用垂直和水平运动的弹性变形模拟可能会对中国的一些构造活动区产生重要的新认识。2008年5月发生的汶川大地震，在一个缓慢收敛但地形极其陡峭的地区，使人们认识到需要更好地了解中国的变形过程。这项研究将使来自中国的GPS时间序列和速度，这是不容易获得的美国调查人员，在一个可用的形式。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The Tibetan Plateau is the largest area of high topography on the planet. Is the Tibetan Plateau rising higher today? Is it growing taller due to ongoing contraction as India continues to collide with Eurasia? Is it collapsing due to extension driven by its excess gravitational potential energy? Is it roughly in balance, no longer growing higher, but simply changing shape? Are parts of the plateau presently evolving in different ways? This project, a joint effort between researchers at the University of Alaska and several Chinese research institutions, aims to address these questions. Global Positioning System (GPS) measurements from the Tibetan Plateau and its surroundings are dense enough and precise enough to make meaningful measurements of vertical motions in Tibet and the rest of the India-Eurasia collision zone. Using several years of GPS data and careful attention to detail in the data analysis, a realistic vertical measurement precision of approximately 1 millimeter per year can be attained even with campaign surveys. Hundreds of campaign GPS sites in China and the rest of the India-Eurasia collision zone now have enough data to provide robust estimates of vertical velocities. These data will be completely reanalyzed the using the next generation of models and orbits, and models to explain the observed rates and spatial variation will be developed. Accuracy will be assessed using vertical rates over a wide area, including regions of no expected deformation, and by comparing estimated GPS vertical motions with complementary data from repeated leveling and InSAR.The relationship of instantaneous vertical rates to long-term geologic uplift or subsidence rates requires more investigation, and this study will be first to focus on systematic regional measurement and modeling of vertical motions in a region of spectacular active tectonics. Improved understanding of crustal deformation will lead to a better understanding of earthquake hazards in China, a heavily populated region prone to earthquakes. Although this project focuses on vertical motions, we a more precise estimate of horizontal motions will also obtained, and the modeling of elastic deformation using both vertical and horizontal motions may produce significant new understanding of some of the tectonically active regions in China. The occurrence in May 2008 of the devastating Wenchuan earthquake, in a region of slow convergence yet extremely steep topography, drives home the need to better understand deformation processes in China. This study will make GPS time series and velocities from China, which are not easily accessible to US investigators, available in a usable form.