jgg     2015 35 (4):  604-607    ISSN: 0412-1961  CN: 21-1139/TG The Application and Method of GPS Strain Field Using the  Least Square Collocation and REHSM 1 School of Geodesy and Geomatics,Wuhan University, 129 Luoyu Road, Wuhan 430079, China 2 College of Geology Engineering and Geomatics, Chang’an University, 126 Yanta Road, Xi’an 710054, China 3 Research Center of GNSS, Wuhan University, 129 Luoyu Road, Wuhan 430079, China Received: 2014-11-11  Revised: null  Online: 2015-07-29 Supporting info