Abstract: In this paper, we analyse focal mechanism solution of the June 24, 2012 Ninglang-Yanyuan M_S5.7 earthquake, distribution feature of aftershocks and disaster distribution of the main earthquake. Then, combining with regional distribution characteristics of the quaternary strata, regional geological structural characteristics and three-dimensional satellite remote sensing image, we proposed that the June 24, 2012 Ninglang-Yanyuan M_S5.7 earthquake is the result of new activity of the North-West extension Yong-ning fault. The Yong-ning fault is of linear extension in image, fault scarp development, the late Quaternary activity and the significance in regional tectonic deformation of the Yong-ning fault needs more study.

Key words: The June 24, 2012 Ninglang-Yanyuan M_S5.7 earthquake, Seismogenic structure, Yong-ning fault, Focal mechanism solution, Disaster distribution, Aftershocks