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区域。今天青藏高原的海拔在升高吗？随着印度继续与欧亚大陆相撞，它是否会因为持续的收缩而变得更高？它的坍塌是由于其超额引力势能驱动的伸展吗？它是不是大致处于平衡状态，不再变得更高，只是在改变形状？高原的部分地区目前正在以不同的方式演变吗？该项目由阿拉斯加大学的研究人员和几家中国研究机构联合开展，旨在解决这些问题。全球定位系统(GPS)对青藏高原及其周围地区的测量密度和精度足以对西藏和印度-欧亚碰撞带其他地区的垂直运动进行有意义的测量。使用几年的GPS数据和在数据分析中对细节的仔细关注，即使是战役测量，也可以达到每年约1毫米的现实垂直测量精度。中国和印度-欧亚碰撞带其他地区的数以百计的运动GPS站点现在拥有足够的数据，可以提供强有力的垂直速度估计。这些数据将使用下一代模型和轨道完全重新分析，并将开发解释观测到的速率和空间变化的模型。精度将使用大范围的垂直速率进行评估，包括没有预期变形的区域，并将估计的GPS垂直运动与重复水准和InSAR的补充数据进行比较。瞬时垂直速率与长期地质抬升或沉降速率的关系需要更多研究，这项研究将首次集中于壮观活动构造区域的系统区域测量和垂直运动建模。提高对地壳形变的了解将有助于更好地了解中国这一人口稠密、易发地震的地区的地震灾害。虽然这个项目的重点是垂直运动，但我们也将获得对水平运动的更准确的估计，使用垂直和水平运动的弹性变形建模可能会对中国的一些构造活动区产生重大的新认识。2008年5月发生的毁灭性汶川地震，在一个收敛缓慢但地形极其陡峭的地区，促使人们更好地了解中国的变形过程。这项研究将使美国调查人员不易获得的中国的全球定位系统时间序列和速度以可用的形式提供。

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.