Minxian,located in southwestern Dingxi City of southern Gansu in the eastern region of the Qinghai Tibet Plateau,borders on Longnan and the West Qinling Mountains and is the geometric center of Dingxi,Tianshui,Longnan,and Gannan.The geological structure of Minxian belongs to the Qinling Mountains Hercynian geosyncline fold belt at the north branch of the Western Qinling Mountains fold belt.At 7:45CST on July 22,2013,an MS6.6 earthquake occurred at the junction of Minxian and Zhangxian with a focal depth of 20km.The earthquake occurred along the north branch Lintan-Dangchang fracture,126km from Dingxi and 17km from Minxian County.Strong tremors were felt by residents in Dingxi,Tianshui,Longnan,and Gannan;those in Lanzhou and Baiyin also detected movement.The Earthquake Administration of Gansu province operates 8deformation observation stations and 15deformation observation projects situated within 300km of the earthquake focus that include DSQ and SSY at Tanchang station;CZB at Wushan station;CZB and YRY at Linxia station;YZ-1at Liujiaxia station;CZB at Lanzhou station;DSQ,SSY,SSY-II,SSQ,and PET at Lanzhou Shilidian station;and DSQ and SSY at Baiyin station.This study focuses on the data of 15observation projects to conduct preliminary analysis,through which abnormal variation was detected in the data of 10projects.Moreover,DSQ and SSY at Tanchang station and CZB at Lanzhou station showed obvious β,β2,and γ1 stages,and CZB at Wushan and Liangshui exhibited obvious β1 and β2 stages.Therefore,deformation anomalies were present prior to the MS6.6earthquake.Although the distance between Lanzhou and Shilidian stations is less than 10km,only DSQ,SSY,and SSY-II at Shilidian exhibited a significant bulge anomaly;SSQ of Shilidian showed no obvious abnormalities.Sucha huge discrepancy in such a close proximity required further explanation.It was determined that the CZB component at Linxia station began to increase rapidly in January 2011and entered a declining trend in August.At the same time,the EW component began to alter from a normal decline,which resulted in significant deformation.These changes are unrelated to the NS component.Therefore,further research is needed to determine the reason for such anomalies.