Abstract The seismic activity characteristics in Dongrangkou area of Badong county of Hubei province have been analyzed since the Three Gorges reservoir impoundment in June,2003.It is shown that the micro earthquakes and the tiny micro earthquakes have a intermittent and waving frequencystrength process. Most of the events occur near the shallow surface layer of sea level,very a few of them occur under the depositional cover layer and all of them display the characteristic of low
Q value. The focal mechanism solutions of ML≥2.0 earthquakes show the different rupture and slippage stress condition of part terrane,there isn’t proof to prove that the earthquake are connected with the southwestern segment of northeast Gaoqiao fault in the northwest of this area.The events do not belong to a group controlled by a bigger seismogenic body and are not of a unify tectonic type.The main inducement of the dense seismic activity in the Dongrang river canyon is depositional cover layer’s stress adjustmentstrain release caused by the gravity unloads of reservoir bank slope and the adjusting tiny displacement of the mountain body under the osmosis of reservoir water.In addition, some of the events are the induced earthquake by mining in the east of canyon.
