青藏高原东北缘老虎山断裂的断层面参数拟合及其几何意义  

THE RESEARCH ON FAULT PLANE SOLUTION AND GEOMETRIC MEANING OF THE LAOHUSHAN FAULT IN THE NORTHEASTERN TIBETAN PLATEAU

作　　者：刘白云 尹志文 袁道阳[3] 李亮 王维欢 LIU Bai-yun;YIN Zhi-wen;YUAN Dao-yang;LI Liang;WANG Wei-huan(Gansu Earthquake Agency,Lanzhou 730000,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Lanzhou University,Lanzhou 730000,China)

机构地区：[1]甘肃省地震局,兰州730000 [2]中国地震局地质研究所地震动力学国家重点实验室,北京100029 [3]兰州大学,兰州730000

出　　处：《地震地质》2020年第6期1354-1369,共16页Seismology and Geology

基　　金：中国地震局地震预测研究所基本科研业务专项(2017IESLZ02);中国地震局地质研究所地震动力学国家重点实验室开放基金(LED2020B01);甘肃省自然科学基金(18JR3RA414);甘肃省应急流动台网运维项目(ZX1903001)共同资助。

摘　　要：文中利用2008—2019年甘肃和周边地震台网20个台站形成的观测报告,以及中国地震科学台阵探测二期项目在南北地震带北段布设的18个流动观测台站于2014—2015年记录的老虎山地区小地震资料,经双差定位方法重新进行了震源位置的修定,获得了700个重新定位的震源资料。重新定位后,研究区内小地震更加集中地沿老虎山断裂呈NW向线性分布,震源深度也明显呈集中分布的趋势,大部分地震均匀分布于0~10km深度范围,显示出该区地震多为浅源地震的特征。依据成丛地震发生在断层附近的原则,采用模拟退火算法及高斯-牛顿算法相结合的方式,精确地获得了老虎山断裂断层面的详细参数(走向为103°、倾角为89°、滑动角为0°),表明该断裂是一条NW走向的高倾角左旋断裂,长约38km,自SE从景泰喜集水(37.05°N,104.05°E)延伸至NW的天祝松山(37.12°N,103.66°E)。将所得结果与1990年天祝MS6.2地震和2000年景泰MS5.9地震的发震构造和震源机制解进行对比可知,反演得到的断层面参数与前人的认识十分吻合。老虎山地表断裂与反演断层面在地表的投影线为相互平行关系,且距离非常近。The Laohushan fault zone is located in the northeast margin of the uplift area of the Tibetan plateau.It belongs to the eastern segment of the Laohushan-Maomaoshan-Jinqianghe Fault in the eastern segment of the North Qilian fault system.It was manifested as compressive thrust in early stage,but its mechanical properties changed into left-lateral strike-slip movement after middle Pleistocene.There occurred the Jingtai MS6.8 earthquake in 1888,Tianzhu MS6.2 earthquake in1990 and Jingtai MS5.9 earthquake in 2000 along the fault in history.With the construction of the national important projects in earthquake industry-"Digital seismic network project of the 10th Five Year Plan"and"Chinese seismic background field detection project",a number of modern seismological stations were built in Gansu Province and its adjacent areas.Contrast with seismographic network,the mobile broadband seismic array has the advantages of relatively dense stations,small spacing,uniform distribution,and high data integrity rate.Combining the two observational methods has gradually become the main development direction at home and abroad.Based on the data of small earthquakes in the Laohushan zone recorded by 20 stations of the digital seismic network in Gansu and its adjacent seismic network during the years of 2008 to 2019,and 18 portable seismographic stations from the 2nd-phase project of China Seismic Detection Array during the years of 2014—2015,we relocated the dense earthquakes by double-difference method and obtained the source parameters for 700 earthquakes.The accurately located small earthquakes distribute along both sides of the Laohushan Fault,which is NW-trending obviously.Most earthquakes distribute at the depth range of 0~10 km of the earth’s surface after the relocation,and the result shows that the focal depths are more concentrated.Generally,the earthquakes are closely related to active tectonics,large earthquakes usually occur on fault zones with obvious activity,but the distribution of small earthquakes is related to

关 键 词：双差定位 老虎山断裂 断层面解 发震构造 

分 类 号：P315.2[天文地球—地震学]