摘要
We have studied the seismicity features of M_S≥5.0 earthquakes two years before strong earthquakes with M_S≥7.0 occurred in the central-northern Qinghai-Xizang (Tibet) block since 1920. The results have showed that there is an obvious gap or quiescence of M_S5.0~6.9 earthquakes near epicenters. We have also studied statistical seismicity parameters of M_S5.0~6.9 earthquakes in the same region since 1950. The results have showed that earthquakes with M_S≥7.0 occurred when earthquake frequency is relatively high and earthquake time, space accumulation degrees are rising. And the prediction effect R value scores are between 0.4~0.7. We have concluded that, before earthquakes with M_S≥7.0 in the central-northern Qinghai-Xizang (Tibet) block, M_S5.0~6.0 earthquake activity in the whole area increased and accumulated in time and space, but earthquakes with M_S≥7.0 occurred where M_S5.0~6.0 earthquake activity was relatively quiet.
We have studied the seismicity features of Ms ≥ 5.0 earthquakes two years before strong earthquakes with Ms ≥ 7.0 occurred in the central-northern Qinghai-Xizang (Tibet) block since 1920. The results have showed that there is an obvious gap or quiescence of Ms5.0 - 6.9 earthquakes near epicenters. We have also studied statistical seismicity parameters of Ms5.0 -6.9 earthquakes in the same region since 1950. The results have showed that earthquakes with Ms ≥7.0 occurred when earthquake frequency is relatively high and earthquake time, space accumulation degrees are rising. And the prediction effect R value scores are between 0.4 - 0.7. We have concluded that, before earthquakes with Ms ≥ 7.0 in the central-northern Qinghai-Xizang (Tibet) block, Ms5.0 - 6.0 earthquake activity in the whole area increased and accumulated in time and space, but earthquakes with Ms ≥7.0 occurred where Ms5.0 -6.0 earthquake activity was relatively quiet.
基金
Theresearchwassupportedunderthe10th"FiveYearPlan"KeyTechnologiesR&DProgramofChinaEarthquakeAdministration(2001BA601B010304).
关键词
地震
活动性
青海
西藏
参数
Central-northern Qinghai-Xizang (Tibet) block
Strong earthquake
Seismicity pattern features
Seismicity parameter