GPS监测慢滑移事件的NIF反演及时空特征分析  

NIF Inversion and Spatiotemporal Analysis of Slow Slip Events in GPS Monitoring

作　　者：严丽 罗正东 赵爱平 李萌 YAN Li;LUO Zhengdong;ZHAO Aiping;LI Meng(Jiangxi Key Laboratory of Watershed Ecological Process and Information(Platform No.2023SSY01051),East China University of Technology,Nanchang 330013,China;Engineering Research Center for Seismic Disaster Prevention and Engineering Geological Disaster Detection of Jiangxi Province,Nanchang 330013,China;Key Laboratory of Mine Environmental Monitoring and Improving Around Poyang Lake of Ministry of Natural Resources,East China University of Technology,Nanchang 330013,China;Nanchang Key Laboratory of Landscape Process and Territorial Spatial Ecological Restoration,East China University of Technology,Nanchang 330013,China;Observatory for Geodynamic of the East Yangtze Block in Jiujiang,Jiangxi Province,Jiujiang 332000,China)

机构地区：[1]东华理工大学江西省流域生态过程与信息重点实验室(平台编号023SSY01051),江西南昌330013 [2]江西省防震减灾与工程地质灾害探测工程研究中心,江西南昌330013 [3]东华理工大学自然资源部环鄱阳湖区域矿山环境监测与治理重点实验室,江西南昌330013 [4]东华理工大学南昌市景观过程与国土空间生态修复重点实验室,江西南昌330013 [5]江西九江扬子块体东部地球动力学野外科学观测研究站,江西九江332000

出　　处：《武汉大学学报（信息科学版）》2024年第12期2199-2209,共11页Geomatics and Information Science of Wuhan University

基　　金：国家自然科学基金(41704031,42061077);江西省自然科学基金(20192BAB217011);江西九江扬子块体东部地球动力学野外科学观测研究站开放基金(OGYB202004);江西省防震减灾与工程地质灾害探测工程研究中心开放基金(SDGD202109)。

摘　　要：研究利用GPS坐标时序与网络反演滤波(network inversion filter,NIF)方法反演慢滑移事件,分析慢滑移的时空特征及演化规律,探讨慢滑移事件与地震发生的关联性。首先,对GPS连续坐标时序构建标准线性轨迹模型,剔除粗差并修复阶跃项,去除震前常数项和稳态速度项,去除年和半年周期季节项,提取慢滑移坐标时序;然后,利用NIF生成断层格网模型,引入弹性格林函数描述断层滑移与地表位移的关系,从而结合GPS慢滑移坐标时序反演断层格网上的滑移矢量及地表位移矢量;最后,统计慢滑移发生前后区域地震发生的大小及频率,分析慢滑移与地震发生可能存在的关系。以日本房总半岛2018年慢滑移事件为例展开研究,结果表明,慢滑移活跃期为年积日156~169;最大累积滑移量约为11.3 cm,最大日滑移率约2.7 cm/d;滑移中心区域为房总半岛东南部,略微向南传播,断层滑移深度由深及浅;此次慢滑移事件发生期间该区域地震发生频率明显增大,之后几个月内地震发生频率逐渐恢复至平常。从房总半岛慢滑移动态演化中可判识潜在地震群逼近的危险性。Objectives:Slow slip events(SSEs)are slow dislocation that occur in weak zones in the crust,and they may cause surface deformations and lead to slow earthquakes.However,the mechanism of SSEs and whether they will trigger earthquakes are still in the stage of discussion and speculation for developing the new principles and methods.To further study the characteristics of SSEs and the relationship with earth-quakes,we use global positioning system(GPS)coordinate time series to invert SSEs.The spatiotemporal characteristics and evolution laws of SSEs are analyzed,and the relationship between SSEs and earth-quakes is discussed.Methods:The proposed method is executed based on standard linear trajectory model(SLTM)and network inversion filter(NIF).First,the slow slip coordinate time series are obtained by modeling GPS continuous coordinate time series using SLTM.The steps are repaired,and the gross errors,the constant,the steady state velocity,and the annual and semi-annual periodic season terms are re-moved.Then,NIF is used to construct the fault grid,and the elastic Greens function is introduced to describe the relationship between fault slip and surface displacement.Using the slow slip coordinate time series and NIF,the slip vectors on the fault grid and surface displacement vectors are inverted.Finally,the magnitude and frequency of the earthquakes before and after SSEs are calculated,and the possible rela-tionship between SSEs and earthquakes is analyzed.Results:Taking the 2018 SSE in Boso Peninsula of Japan as an example,the results show that the active period of the slow slip ranges from the 156th to the 169th days.The maximum cumulative slip is about 11.3 cm,and the maximum slip rate is about 2.7 cm/d.The central area of the slow slip is located in the southeast of Boso Peninsula(140.2°E-140.9°E,34.8°N-35.6°N).The SSE spreads southward slightly,and the depth of the slow slip changes from deep(about 23 km)to shallow(about 15 km).The frequency of regional earthquakes increases significantly during the SSE,and

关 键 词：GPS 慢滑移事件 网络反演滤波 时空特征分析 

分 类 号：P228[天文地球—大地测量学与测量工程]