浙江珊溪水库地震:震源参数测定及断层结构和应力状态描述

英文篇名：Earthquakes in the Shanxi-Reservoir,Zhejiang Province:source parameters determining and description of the tectonic fault and static stress status
中文刊名：地震地磁观测与研究
英文刊名：Seismological and Geomagnetic Observation and Research
作者：李金龙 ; 邹振轩
英文作者：Li Jinlong and Zou Zhenxuan(Earthquake Administration of Zhejiang Province ; Hangzhou 310013 ; China)
中文关键词：震源参数 ; 遗传算法 ; Brune ω~2模型 ; 应力状态
英文关键词：source parameters ; genetic algorithms ; Brune ω~2 model ; stress status
出版日期：2008-02-25
机构：浙江省地震局,浙江省地震局,
年：2008
期：01
出版单位：地震地磁观测与研究

摘要

利用遗传算法,搜索符合Brune ω2模型的拐角频率(fc)及零频幅值(Ωc)的最佳值,测定浙江珊溪水库震区88条小震(1.5≤ML≤4.6)的地震矩(M0)、震源尺度(r)及静态应力降(Δσ)。地震矩M0在1010~1014N.m范围内,与拐角频率fc遵循M0∝fc-3的规律;震源尺度和地震矩、应力降之间呈现多重标度特征,地震矩大于临界值2.3×1012N.m(相应的震源尺度特征值约160m)时,震源尺度与地震矩的关系较强;而应力降(Δσ)在震源尺度大于160m后基本趋向恒定,不随震源尺度的增大而增大。浙江珊溪水库震区自2002年7月以来,经历2次大规模的震群活动。震群释放的应力降大小与该震群的规模成正比关系,大的应力降集中在发震断层中段5~6km深度的区域,其发生时间既可以在主震之前,也可以在主震之后。
The seismic moment(M0),source dimension(r),and static stress drop(Δσ)of 88 small earthquake occurred in the Shanxi-Reservoir,Zhejiang Province,were determined using genetic algorithms to searching the low-frequency flat levels(Ωc)and corner frequencies(fc)with the best-fitting Brune ω2 model.The seismic moment varied between 1010-1014 N·m,versus the corner frequency followed the scaling law M0∝ f-3c;Source dimension,versus the seismic moment and static stress drop,were multi-scaling characteristic,dependency of the source dimension on the seismic moment were stronger while seismic moment greater than 2.3×1012 N·m with the source dimension(r)equals 160 m;Stress drop tend to be invariant while source dimension greater than 160 m.Since July 2002,two greater earthquake swarms occurred in the Shanxi-Reservoir.The stress drop level depends on the magnitude of earthquake swarm.The greater stress drop concentrated in 5-6 km depth on the fault plane,after or before the main-shock.

引文

康英,郑斯华等.2004.中小地震震源参数的求解及其相似关系[J].华南地震,24(2):11～21
    兰从欣,刘杰等.2005.北京地区中小地震震源参数反演[J].地震学报,27(5):498～507
    李金龙,邹振轩等.2006.珊溪水库震群的地震定位[J].地震地磁观测与研究,28(1):14～18
    刘丽芳,刘杰等.2006.姚安地震序列与大姚地震序列震源参数的对比研究[J].地震,26(1):10～18
    钟羽云,朱新运等.2004.温州珊溪水库ML3.9震群震源参数特征[J].地震,24(3):107～114
    朱新运,钟羽云等.2004.地震波拐角频率对地震序列的依赖性研究[J].西北地震学报,26(2):131～136
    邹振轩.2005.浙江地区地震波衰减和场地响应研究[J].地震地磁观测与研究,26(6):9～16
    邹振轩.2006.应用Moya方法反演浙江地区震源参数和台站场地响应[J].东北地震研究,22(1):40～46
    Frankel Aand Wennerberg L.1989.Microearthquake Spectra fromthe Anza,California,Seismic Network:Site Responseand Source Scaling[J].Bull SeismSoc Am,79,581～609
    I manishi K,Takeo M.2004.Source Parameters and Rupture Velocities of Microearthquakes in Western[J].Bull SeismSocAm,94,1762～1780
    Moya A,Aguirre J andIrikura K.2000.Inversion of Source Parameters and Site Effects fromStrong Ground Motion Recordsusing Genetic Algorithms[J].Bull SeismSoc Am,90,977～992
    Parolai S et al.2007.Source Parameters and Seismic Moment-Magnitude Scaling for Northwestern Turkey[J].Bull SeismSoc Am,97,655～660
    Zheng Sihua(郑斯华),Wang Yuk Lung(黄玉龙).2004.Seismic ground motion relationships in southern China based on sto-chastic finite-fault model[J].Earthquake Engineering and Engineering Vibration,3(1):11～21