Some puzzles come from Wenchuan great earthquake： how did Wenchuan great earthquake took place and how can great earthquake avoid？ The deep crust structure of Songpan--Ganzi folded belt in Sichuan shows that the focus depth of Wenchuan great earthquake （ 2008 ） , Maoxian great earthquake （ 1933 ） , Songpan-Pingwu great earthquake（ 1996） were same with the low velocity and high conductive layer of the mid-crust, and they might be related to this layer. Moreover, Yinchuan earthquake, Haiyuan earthquake, Weinan earthquake, Tangshan earthquake, Haicheng earthquake were also related to the low velocity and high conductive layer. All of these earthquakes might be caused by the earth outgassing. Based on the integrative survey on the earthquake, forest fire and petroleum resources, some seismogenic structure region can be explored, and through effluent of oils and gases, the possibility of the earthquake might be decreased.