REGULARITY OF SEISMIC MIGRATIONS IN BADONG CATCHMENT OF THREE GORGES RESERVOIR AREA

Since the impoundment of the Three Gorges Reservoir, thousands of reservoir earthquakes associated with reservoir storage occurred in Badong County. The largest recorded magnitude is 5.1. In recent years, about 50 related papers have been published, which focused on the aspects including the focal mechanism solutions of reservoir earthquake and the relationship with water level in the front dam, and the genetic mechanism of single reservoir earthquake and the micro earthquake swarms. There is a lack of research on reservoir earthquake time periodicity and spatial expansion regularity. On the basis of the field geological survey(including the spring flow survey) and the literature published in recent years, this paper presents a deep study on the earthquake evolution process of reservoir part in Badong County. Results are as follows:(1)The outbreak of Badong reservoir earthquake has specific temporal periodicity, which is shown as long and short cycles. (2)Reservoir earthquakes of karst collapses manifested as linear distribution, and their formation mechanism is closely related to higher pores water pressure and dynamic water pressure process. (3)Field investigation results of spring water also indicate that the reservoir earthquakes of Badong section in Three Gorges Reservoir area have close pertinence with karst collapses, and its spatial expansion mechanism is proposed in the paper.