辽宁海城及其邻区地震活动性研究  

Study on the Activity of the Earthquakes of Haicheng Region in Liaoning Province

作　　者：刘财[1] 郑确[1] 田有[1] 柳云龙[1] 冯晅[1] 

机构地区：[1]吉林大学地球探测科学与技术学院,长春130026

出　　处：《吉林大学学报（地球科学版）》2014年第4期1348-1356,共9页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41174068;41174080);国家"973"计划项目(2009CB219301)

摘　　要：由于受到台站分布不理想、速度结构研究不准确以及震相拾取误差等因素的影响，常规地震定位结果精度较低。因此，研究收集了辽宁省地震台网的地震目录及震相数据，采用双差地震定位方法，对海城及其附近地区（39°N —43°N，120°E— 126°E）20 a 的1400多次地震进行重新定位。与原始定位结果相比，双差定位结果表明：1）震中更加呈条带状集中，尤其在40．5°N —41．0°N，122．0°E—123．0°E 区间，与该地区的海城河大洋河断裂带走向相一致；2）该地区地震多发生于地下5～20 km，与该区中地壳存在的低速高导层相对应；3）深度剖面图显示，大部分地震沿垂直向下柱状分布，原因是该处有粉碎性破裂带，从地下25 km 处延伸到近地表。双差定位算法使得定位后均方根残差的平均值由0．74 s 下降到0．26 s。辽宁地区的地震震级与发生地震数量有关，地震数量陡然增多，大地震发生概率增大。Limited by the distribution of stations,velocity structures and the uncertainty of picking arrivals,the precision for the relocation of earthquakes is usually not sufficient.We collected the data of arrival times recorded by the seismic networks and then used the double-difference method to relocate 1 400 earthquakes occurred in Haicheng region （39°N-43°N,120°E- 126°E）in the last 20 years. Comparing to the original results of the earthquake locations,the results obtained by the double-difference method in this study indicate that：1）The earthquake distributions become more convergent, especially in the region between 40.5°N and 41.0°N and between 122.0°E and 123.0°E,and more consistent with the trend of the fault along the Haicheng Dayang River;2 ）Most of earthquakes occurred in the depth from 5 to 24 km,because there exists a low-velocity and high-conductivity zone in＆amp;nbsp;the crust;3）From the cross sections,many earthquakes distribute as a shape of columnar along the depth because there exists a comminuted fracture zone which extending from the surface to the depth of 25 km.The root-mean-square travel-time residual reduces from 0.74 s to 0.26 s after the relocation using the double-difference method.The study also indicates that the magnitude is related to the number of earthquakes in this region.If the number of earthquakes increases abruptly,the probability for the occurrence of a large earthquake increases as well.

关 键 词：双差定位方法 断裂 地震预测 辽宁海城 

分 类 号：P631.4[天文地球—地质矿产勘探]