青藏块体及周缘潜在震源与强震关系研究

STUDY ON RELATIONSHIP OF POTENTIAL HYPOCENTER TO STRONGEARTHQUAKES IN QINGHAI-TIBET BLOCK AND ITS MARGINS

利用 1993～ 1999、1999～ 2 0 0 1年青藏块体东北缘以及 1991～ 2 0 0 0年中国大陆GPS水平运动年速率资料 ,基于单一力源模型 ,反演获得了青藏块体及其周缘地区 2 0 0 0～ 2 0 0 1年 10次地震的震前资料反映的潜在震源参数。所得力源中心位置距实际震中的距离相对较小 ,其中 2 0 0 0年景泰 5 .9、2 0 0 1年宁蒗 5 .8、昆仑 8.1及格尔木3次 5 .7、5 .8级地震均在 5 0km左右 ;2 0 0 0年兴海 6 .6、2 0 0 1年施甸 5 .9、永胜 6 .0级地震不到 10 0km ;2 0 0 1年雅江 6 .0级地震最远 (12 1km)。此外 ,1999～ 2 0 0 1年青藏块体东北缘地区的反演结果表明 ,沿东昆仑构造带的昆仑山口—达日及库玛断裂向东至甘东南、甘青交界区域 ,可能仍存在潜在震源。

By using the horizontal movement data observed by GPS during 1993-1999 and 1999-2001 in the northeastern margin of Qinghai-Tibet block, together with the same kind of data measured during 1991-2000 in China Mainland and on the basis of singular force-source model the parameters of potential hypocenters reflected by the precursory data of the 10 earthquakes occurred during 2000-2001 are inverted out. The distances between obtained force-source centers and real epicenters are small, for example,for earthquakes of Jingtai 5.9 in 2000, Ninglang 5.8, Kunlun 8.1 and three Gelm 5.7, 5.8 in 2001 they are about 50 km; and of Xinghai 6.6 in 2000, Shidian 5.9 and Yongsheng 6.0 in 2001 100 km less;for Yajiang 6.0 it is the longest:121 km. Moreover, the inversion result from the data of 1999-2001 in the northeastern margin of Qinghai-Tibet block indicates that eastwards along Kunlun Mountain pass-Dari and Kuma faults of East-Kunlun tectonic belt and extending eastwards to southeastern Gansu and the boundary zone between Gansu and Qinghai, it is still possible for potential hypocenters to exist.