松原地区地震发震机制与迁移特点研究  

Research on seismogenic mechanism and migration characteristics of the earthquakes in the Songyuan area

作　　者：阮庆丰 刘俊清 田有[1,3,4] 刘财 张宇[5] 蔡宏雷 RUAN QingFeng;LIU JunQing;TIAN You;LIU Cai;ZHANG Yu;CAI HongLei(College of Geo-exploration Science and Technology,Jilin University,Changchun 130026,China;School of Geomatics and Prospecting Engineering,Jilin Jianzhu University,Changchun 130118,China;Key Laboratory of Geophysical Exploration Equipment,Ministry of Education,Jilin University,Changchun 130026,China;Changbaishan Volcano Geophysical Observatory,Ministry of Education,Changchun 130021,China;Jilin Earthquake Agency,Changchun 130117,China)

机构地区：[1]吉林大学地球探测科学与技术学院,长春130026 [2]吉林建筑大学测绘与勘查工程学院,长春130118 [3]吉林大学地球信息探测仪器教育部重点实验室,长春130026 [4]长白山火山综合地球物理教育部野外科学观测研究站,长春130021 [5]吉林省地震局,长春130117

出　　处：《地球物理学报》2022年第9期3309-3321,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41874125,41874049);中央高校基本科研业务费资助。

摘　　要：本研究重新拾取震相到时,对2003—2021年松原地区发生的地震进行了绝对定位,采用双差层析成像法在松原地区获得0~20 km深度的高分辨率三维V_(P)和V_(S)模型,对该区地震的发震机制、地震迁移与震源区速度结构之间的关系等进行了深入讨论.结果显示:2003—2021年松原地区地震总体沿着松原—肇东断裂呈北北东向展布.震源区(123°E—125°E,44°N—46°N,0~15 km)的泊松比变化范围为0.24~0.30,平均值为0.242,低于0.3,推断震源区地壳内部几乎不存在部分熔融.绝大多数地震发生在低P、低S波速度异常处,推测震源区下方热物质上涌所携带的流体注入到地壳后触发了松原地区地震.研究区下方5~10 km深度现存在一条连接松原市、前郭县和长岭地区,北北东走向的S波低速带,推断松原—肇东断裂为深部流体提供了通道,控制了地震呈北北东向串珠状展布,且地震随时间具有回跳的迁移特点.根据断裂弱化模型推测松原地区发生更大地震的可能性较低,但在长岭地区,小地震可能会持续发生.The absolute locations of earthquakes occurred in the Songyuan area from January 2003 to February 2021 are obtained by re-picking the arrival times of the seismic phases.Then the high-resolution 3D V_(P)and V_(S)structures at depths of 0 km to 20 km are calculated using the double-difference tomography method.After that,the relationship between the seismogenic mechanism,earthquake migration,and velocity structure in the source region are explored.The results show that the earthquakes occurred from 2003 to 2021 are generally distributed along the Songyuan-Zhaodong fault in a north-northeast direction.The Poisson's ratio in the source region(123°E—125°E,44°N—46°N,0~15 km)varies between 0.24 and 0.30,with an average value of 0.242 which suggests that there is almost no partial melting within the crust in the source region for the value is lower than 0.3.The most of earthquake focuses are located in the low-velocity zone.It is speculated that these earthquakes were triggered by the fluid injection into the crust,which was carried by the upwelling of hot material beneath the source region.A north-northeast S-wave low-velocity belt is found at about 5~10 km beneath the source region,which connects Songyuan City,Qianguo County,and Changling area.It is inferred that the Songyuan-Zhaodong fault provides a pathway for the upwelling of deep fluids,and controls the north-northeast bead-like distribution of earthquakes.In addition,the earthquake migration shows a characteristic of rebounding with time.According to the fault-weakening model,in consequence,the probability is low for a high-magnitude earthquake occurrence in the Songyuan area,but low-magnitude earthquakes may continue to occur in the Changling area in the future.

关 键 词：松原地区 前郭地震 地震迁移性 速度结构 发震机制 

分 类 号：P315[天文地球—地震学]