The Dengjiaqiao reservoir is located in Yidu county of Hubei province, and produces a storage capacity of about 4X10⁵M³. since June 1980 rainstorms continuously taken place in the west part of Hubei province. Reservoir was first fully impounded on 31 July of 1980, thus earthquake (M_L=1.9) was induced the next day.
Secimicity of the Dengjiaqiao reservoir is an event of tectonic-earthquakes type, Due to stormily increasing of rainfall and ground water flowing into underground streams, and permeating into fractures, and so pore pressure increased in some faults, and effective normal stress was decreased, In addition, full impounded lodging also made normal stress increase about 1 bar. This resulted in forming a fracture slip of the fault in NE direction.