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Yang B.,The First Monitoring Center | Zhu S.,The First Monitoring Center | Yang G.-H.,The First Monitoring Center | Zhou W.,The First Monitoring Center | And 2 more authors.

Using the mobile GNSS observations of 1999-2007, 2007-1999, and continuous GNSS observations since 2010. 5 and their processing results, horizontal deformation field and its changes before the Minxian-Zhangxian MS6.6 earthquake have been analyzed. We found that (1) the Minxian-Zhangxian MS6.6 earthquake occurred in the transition area of crust movement, in which movement magnitude is smaller and horizontal deformation is relatively weak; (2) the maximum principal strain of this earthquake zone in 1999-2007 is transition zone from positive to negative strain, the minimum principal strain in 2009-2011 also is transition zone from positive to negative strain, which is relatively large in 1999-2007; (3) the maximum shear strain of this earthquake zone is relatively small, and also is transformation zone for the left and right rotary; (4) the result of the continuous station shows that the earthquake happened in a almost pure thrust tectonic regime, the coseismic deformation is small, its scope is in the range of 10 kilometers from the epicenter; (5) there are no anormaly found in short-time GNSS observations before the earthquake, but there is anabnormaldeformation deficit in trend. Source

Bo W.-J.,The First Monitoring Center | Su J.-F.,The First Monitoring Center | Zhou H.-T.,The First Monitoring Center | Du X.-S.,The First Monitoring Center | And 2 more authors.

Great earthquakes often occur along active fault belts or near by, thus, the monitoring and researches on fault deformation is quite important. Short leveling, short baseline, and integrated monitoring across fault belts etc. have been used to monitor fault activities for many years. GNSS data are mainly used to study horizontal movements in large areas and crust block activity. In this paper, some applications and new explorations of GNSS for researches on fault deformation are introduced and discussed as follows: (1) Monitoring and study on horizontal sliding of fault with GNSS; (2) Monitoring and study on vertical movement of fault with GNSS; (3) By studying the orderliness of crust block deformation on both sides of the fault and setting up models of blockmovement and strain, the fault's deformation can be deduced from the models, and then the comparison between the deduced deformation and that monitored directly across faults can be done. Our study shows that the larger the differences of deformation between them, the stronger the action has between two blocks. This will be very important for prediction of earthquake location and seismic risk estimation. Source

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