摘要
选取2005—2014年宁夏地震台网记录的889次M_L≥2.0地震的近场台站数字地震波形资料,利用这些波形高信噪比的尾波时间域信号,通过Sato模型计算地震波传播路径上的尾波Q_c(f)值;拟合Q_c(f)值与频率f之间的关系,研究宁夏不同区域尾波衰减Q_c(f)的变化特征。本研究根据噪声条件及计算要求从近场14个台站中挑选出3 261条三分向记录,计算尾波衰减参数,得到宁夏全区域Q_c(f)随频率的变化为Q_c(f)=(39.23±9.68)f^(0.979±0.083);结合研究区同期地震活动水平及地震地质构造特征将研究区划分为北部,中部及南部三个次级区域;对应三个次级区域分别拟合Q_c(f)对频率的关系为Q_c(f)=(43.05±11.05)f^(0.952±0.083);Q_c(f)=(38.76±9.15)f^(0.974±0.078);Q_c(f)=(37.03±7.99)f^(1.002±0.081)。结果表明:整体上宁夏地区为高衰减低频率依赖性区域,宁夏北区、中部及南区尾波Q0值依此降低,对频率的依赖性指数表现出负相关关系。数据结果较好地反映了不同的地质构造及地震活动强弱特征。
We have adopted waveform data of 889 ML≥2. 0 earthquakes recorded at near- source stations from 2005 to 2014, which were recorded by Ningxia seismic network. By using the coda time series with high signal-to-noise ratio, based on Sato model, the coda Qo（f） was calculated, and the relationship between Qc （f） and frequency f was obtained. Then, the characteristics of Qo （f） in the Ningxia area were analyzed. According to the noise conditions and computing requirements, 3 261 three-component records chosen from 14 stations were used in this study. Our result shows that the relationship between the coda Qc（f） and f of Ningxia region is Qc（f）= （39.23±9.68） f0. 979±0. 083, suggesting that the study area of Ningxia is a tectonically inactive zone, but the dependence on frequency is higher. According to the regional seismic tectonic characteristics and the homochronous seismic activity, further analysis on the relationship between Qc （f） and f was carried out. We divided the study area into three partitions： （a） Northern Region; （b） Central Region; （c） Southern Region, the relationship between the coda Qc（f） and f are respectively： Qc（f） = （43.05 ± 11.05）f^0.952±0.083 ; Qc（f） = （38. 76±9. 15）f^0.974±0.078 ; Qc （f） = （37.03±7.99）f^1.002±0.081. They reflect the whole area of Ningxia is a high attenuation of low frequency dependent region. From Northern Ningxia.central and Southern the Q0 value of coda decreases in turn, the dependence of frequency index shows a negative correlation. The results reflect the characteristics of different geological structures and seismic activities.
作者
张锦玲
朱新运
马起杨
金春华
ZHANG Jin-ling;ZHU Xin-yun;MA Qi-yang;JIN Chun-hua(Earthquake Agency of Ningxia Hui Autonomous Region,Yinchuan 750001,China;Zhejiang Earthquake Agency,Hangzhou 310013,China)
出处
《地震》
CSCD
北大核心
2018年第4期74-83,共10页
Earthquake
基金
中国地震局星火计划攻关项目(XH18019)资助
