Determination and interpretation of glacial-isostatic deformations of the Earth's crust in West Greenland

过去和现在的冰体变化及其与地球流变学和全球海洋质量再分布的相互作用引起了地壳载荷变形的复杂模式。在西格陵兰岛南部，冰期历史特别复杂，包括全新世晚期的一次冰川再推进。目前对这一冰期历史的认识尤其不确定，部分原因是由于对现今地壳变形的测量覆盖范围不够。本项目将通过精确的大地测量卫星导航系统测量来确定西格陵兰岛地壳的变形。将开展实地运动，重新观测1995年建立并于2002年首次重新观测的全球定位系统网络的14个站点。另外11个在2004年至2010年间加入该网络的地点将被重新观测，其中大部分是第一次。此外，将在现有的活动站点网络中增加两个连续的GNSS站点。除了对以前的测量进行定量扩展之外，新的观测将使科学开发达到新的质量。这样，就有可能对这一冰原边缘区域的地壳形变进行一致的、基于数据的描述。新的全球导航卫星系统观测数据将与申请人组自1995年以来收集的数据以及补充的格陵兰GPS网项目和国际全球导航卫星系统服务的数据一起处理。将使用伯尔尼全球导航卫星系统软件，并特别注意采用长期一致的参考系统。对结果坐标变化的分析将同时考虑垂直分量和水平分量。特别关注的是东西剖面的变形梯度。为了解释观测到的地壳变形，将分别考虑对正在进行的冰质量变化的弹性响应和对过去载荷变化（冰川均衡调整，GIA）的（暂时线性的）粘弹性反应。弹性载荷变形将根据卫星观测（如卫星测高和卫星重力测量）得出的当前冰块质量变化进行模拟。减去弹性分量后，就可以得到地震诱发的地壳变形估计。它们将用于验证GIA模型（以及冰川历史模型），并将与跨学科合作伙伴一起纳入进一步的研究。

Past and present changes of ice masses and their interaction with Earth rheology and global oceanic mass redistribution induce complex patterns of load deformations of the Earth crust. In the southern part of West Greenland, the glaciation history is particularly complex, including a glacial re-advance in the late Holocene. Current knowledge of this glaciation history is particularly uncertain, which is partly due to insufficient coverage by measurements of present-day crustal deformation.The present project will determine deformations of the Earth crust in West Greenland by precise geodetic GNSS measurements.Field campaigns will be carried out to re-observe the 14 sites of a GPS network which was established in 1995 and was first re-observed in 2002. Additional 11 sites which have been added to the network between 2004 and 2010 will be re-observed --- mostly for the first time. Moreover, two continuous GNSS sites will be added to the existing network of campaign sites.Beyond a quantitative extension of previous measurements, the new observations will allow for a new quality of scientific exploitation. In this way, a consistent, data-based description of crustal deformations in this sector of the ice sheet margin will become possible.The new GNSS observation data will be processed together with the data gathered since 1995 by the group of the applicants and with data from the complementary GNET (Greenland GPS Network) project and from the IGS (International GNSS Service). The Bernese GNSS Software will be used, with special attention on the application of a long-term consistent reference system.The analysis of the resulting coordinate changes will consider both the vertical component and the horizontal components. Special focus will be put on the gradients of deformation along East-West profiles. For the interpretation of the observed crustal deformations, the elastic response to ongoing ice mass changes and the (temporally linear) visco-elastic reaction to past load changes (glacial isostatic adjustment, GIA) will be considered separately. The elastic load deformation will be modelled based on present-day ice mass changes derived from satellite observations such as satellite altimetry and satellite gravimetry.After subtraction of the elastic component, estimates of GIA-induced crustal deformations will be obtained. They will be used to validate GIA models (and hence models of glaciation history) and will be incorporated in further studies with interdisciplinary partners.