A Unified Crustal Motion Model for Continental East Asia

该项目旨在提高我们对东亚大陆地壳运动的了解，在东亚大陆，第四纪构造可以说是全球大陆变形带中最活跃和最复杂的。将对过去二十年从不同网络观测到的区域全球定位系统数据进行分析，以编制统一的地壳运动图，并将其提供给科学界。统一的地壳运动模型有着广泛的应用，从构造变形研究、地球动力学模拟到地震危险性评估。该项目还将更新断层滑动估计的断层网络模型，这将是对地壳形变建模方法发展的重大改进。该模型将加深我们对形变如何划分为不同大小断层的理解，并有助于解决大陆地壳/岩石圈变形样式的突出争议。对单个断层上地震矩累积率的估计将有助于评估整个地区的地震危险性，特别是沿喜马拉雅、天山和帕米尔-兴都库什造山带。将培训一名研究生处理大地测量数据并进行地壳形变建模研究。该项目还将有助于加强与中国科学家的国际合作，并与俄罗斯和印度科学家建立新的合作关系。通过不同的区域大地测量网络收集了东亚大陆20多年的GPS观测数据，并对它们的数据进行了分析，以推断不同区域尺度的形变场。然而，这些数据通常是使用不同版本的全球定位系统数据处理软件并采用不同的地球物理模型和参数进行分析的，在许多情况下会导致重大误差和(或)解决方案之间的不一致。这项研究将收集所有在东亚大陆测量的运动GPS数据，使用最新的软件和具有一致参数的轨道和地球物理模型对数据进行统一的再处理。因此，将最大限度地减少运动解决方案内部和之间的数据处理误差，并将产生一套长期速度、同震和震后位移的统一解决方案。这一结果将与现有的连续GPS解决方案相结合，最终产品将帮助解决多个地区的详细变形模式，提高解的精度，并为断层上的滑移率提供更好的约束。PI小组先前开发的故障网络模型中将实施一种“回滑”算法。该算法通常只用于块体运动模型，它的引入将克服块体运动和位错断层分段方法等其他方法的一些不足，并能更好地模拟单个断层周围的弹性应变积累，特别是推覆/正断层周围的变形场。改进的方法和程序将用于反演GPS速度数据的断层滑动速率，并有助于描述东亚大陆的形变来源、模式、机制和地震潜力。

This project aims to improve our knowledge of crustal motion in continental East Asia, where the Quaternary tectonics is arguably the most active and complex among global continental deformation zones. Regional GPS data observed in the past two decades from different networks will be analyzed to produce a unified crustal motion map that will be provided to the scientific community. The unified crustal motion model has a wide range of application, from tectonic deformation study, geodynamic modeling, to seismic hazard assessment. The project will also update a fault network model for fault slip estimation, which will be a significant improvement in methodology development for crustal deformation modeling. The resulting model will improve our understanding of how deformation is partitioned to faults of various sizes, and help address the outstanding controversy on deformation style of continental crust/lithosphere. The estimation of seismic moment accumulation rates on individual faults will help assess seismic hazard across the region, particularly along the Himalaya, Tien Shan, and Pamir-Hindu Kush orogens. A graduate student will be trained to process the geodetic data and conduct research on crustal deformation modeling. The project will also help strengthen international collaboration with Chinese scientists and establish new collaborations with Russian and Indian scientists. More than two decades of GPS observations have been gathered in continental East Asia by various regional geodetic networks, and their data were analyzed to infer deformation fields at various regional scales. These data were usually analyzed, however, using different versions of GPS data processing software and employing different geophysical models and parameters, in many cases resulting in significant errors and/or inconsistencies between solutions. This research will collect all the available campaign GPS data surveyed in continental East Asia, reprocess the data uniformly using the up-to-date software and orbital and geophysical models with consistent parameterization. Thus data processing errors within and between campaign solutions will be minimized, and a set of unified solutions for secular velocities and coseismic and postseismic displacements will be produced. This result will be combined with existing continuous GPS solutions, and the final product will help resolve detailed deformation patterns across multiple regions with improved solution accuracy, and provide better constraints for slip rates on faults. A "back-slip" algorithm will be implemented into the fault network model that the PI group has previously developed. Introduction of the algorithm, which is usually used for block motion models only, will overcome some of the deficiencies that other methods such as the block motion and dislocation fault segment methods have, and better simulate elastic strain buildup around individual faults, particularly for deformation fields around thrust/normal faults. The improved method and the code will be used to invert GPS velocity data for fault slip rates, and help characterize deformation sources, patterns, mechanisms, and earthquake potentials in continental East Asia.