青藏块体东北缘潜在强震震源研究

Study on the Potential Macroseismic Sources in the Northeast Margin of Qinghai-Tibet Block

依据单一力源模型的基本原理 ,利用青藏块体东北缘多年来水准观测垂直位移资料 ,反演该区 2 0a来中强地震的潜在震源力学参数与未来可能的危险区域 ,得到 :①如果确定所选研究区仅有一个等价强震力源 ,反演的强震力源与实际震中符合度较好 ,这对中强地震地点的预测有一定的参考价值 ;②在青藏块体东北缘6级左右的地震 ,比较合理的可研究范围一般为震源有效半径的 1 0倍 ,对应的等价力源的量级约为 1 0 1 1 N ;③从 1 995～ 2 0 0 0年的分区模拟结果看 ,在祁连的中段存在一个潜在的等价强震力源 (1× 1 0 1 1 N) ;另外 ,在青海与甘肃南部交界处存在一个潜在的等价强震力源 ,该力源深度为 5km ,大小达到 5× 1 0 1 1 N。

According to the principal of Single-force Model, using the vertical displacement data got through the leveling survey in the northeast Margin of Qinghai-Tibet Block, the potential dynamic source parameters of moderate-strong earthquakes in the past 20 years and the possible danger areas are inversed.Then, the following viewpoints are got.(1) The inversed Macroseismic Sources will be in good accordance with the real epicenters if the selected region has only one equivalent strong-force source.This dresult is referential for the prediction of strong earthquakes,epicenter.(2) In the northeast margin of Qinghai-Tibet Block,for the earthquakes with magnitude about 6 0, the reasonable study area is 10 times of the effective real source area and the strength of related force is about 10 11 N.(3) Judging from the inversion of sub-area in the period from 1995 to 2000, there exists a strong force which is 10 11 N in the middle part of Qilian Mountains.Besides, there exists another strong force, which is 5km deep and 5×10 11 N in the boundary area between Qinhai Province and south Gansu Province.