jgg     2015 35 (3):  445-448    ISSN: 0412-1961  CN: 21-1139/TG Inversion of Tectonic Stress Field in Sichuan-Yunnan Area Using  EGM2008 Model and Ground Gravity Observation 1 Xi’an Research Institute of Surveying and Mapping, 1 Mid-Yanta Road, Xi’an 710054,China 2 State Key Laboratory of Geo-Information Engineering, 1 Mid-Yanta Road, Xi’an 710054,China 3 Technical Division of Surveying and Mapping, 36 Xiying Road, Xi’an 710054,China Received: 2014-06-16  Revised: null  Online: 2015-06-02 Supporting info