A Unified Crustal Motion Model for Continental East Asia

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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.