The Influence Of Reservoir On Surrounding Seismic Activity

Reservoir-induced seismicity(RIS) is an earthquake that after the reservoir impounds to form an artificial lake. And these earthquakes often have some different phenomena appear to the natural earthquake, hereinafter referred to as reservoir earthquake. Reservoir induced earthquake has many special properties compared with natural earthquake. Magnitude of reservoir induced earthquake usually is not high, but the seismic source of reservoir induced earthquake generally is shallow and the epicenter intensity is high. Besides, the epicenter is close to important water conservancy projects. So destructive is very big. Big reservoir induced earthquake will destroy water conservancy facilities; can also lead to serious secondary disasters crisis to the downstream of river. So the study on the reservoir induced earthquake is a very meaningful thing. 2008 wenchuan earthquake, the epicenter happened to be near a large zipingpu reservoir which causes the attention of people.At first, this paper enumerates the reservoir earthquake has happened before. From the angle of earthquake examples reservoir seismic profiles were analyzed, and then understand the predecessors' study of reservoir induced earthquake, summing up the existing results, summarizes the characteristics of the reservoir induced earthquake and the possible causes. Collect the zipingpu reservoir area and the surrounding area of geological tectonic environment data, tectonic stress environment and the hydrogeological structure, etc., used 3D model for the half space, a closer to the actual reservoir model is established. And then with the concept of coulomb failure stress, using the Green function method. And the optimization of Green function is calculated on. Since the reservoir impounded to the wenchuan earthquake occurred, we calculate the relationships between the reservoir water storage variations and pore pressure changes(coulomb failure stress changes). And then on the basis of the analysis of the effect of water activity on the local seismicity, combined with the double difference earthquake algorithm, wenchuan earthquake and the local seismicity are more detailed analyzed. But through the coulomb failure stress calculation, in 12 to 20 km(wenchuan earthquake are 15.5 km) deep, coulomb failure stress are negative, numerical value between 0.5 to 1.5 kPa, suggests that the reservoir has some inhibitory effect on wenchuan earthquake.