广西龙滩库区地震拐角频率时空差异性特征*
陆丽娟,黄树生,张 帆,周 斌,阎春恒

(广西壮族自治区地震局,广西 南宁 530022)

龙滩水库; Brune模型; 震源参数; 拐角频率

Characteristic of Temporal and Spatial Differences of Corner Frequency of the Earthquake in Longtan Reservoir of Guangxi
LU Li-juan,HUANG Shu-sheng,ZHANG Fan,ZHOU Bin,YAN Chun-heng

(Earthquake Administration of Guangxi Zhuang Autonomous Region,Nanning 530022,Guangxi,China)

Longtan Reservoir; Brune model; epicenter parameter; corner frequency

备注

采用2006年9月～2013年7月广西龙滩数字地震台网记录的1 284次ML≥1.0地震波形资料,利用Brune模型,通过几何扩散校正、介质衰减校正、仪器校正等将速度记录谱归算为震源位移谱方法,通过遗传算法计算拐角频率及零频极限,最后计算出地震矩、震源破裂半径等震源参数。对拐角频率特征进行了研究,结果表明:广西龙滩水库库区地震拐角频率存在明显的局部差异性,离坝首较近的坝首地震丛地震的拐角频率与地震矩关系不明显; 离坝区越近,拐角频率与水位变化关系在时间上的一致性更强,负相关关系也越明显,同时拐角频率也相对较低。2010年9月18日广西天峨与贵州交界的ML4.8地震发生在拐角频率上升阶段,此前1年多拐角频率的变化较为稳定。

Using the Brune model and the 1 284 ML≤1.0 seismic wave data recorded by Guangxi Longtan Digital Seismic Network from Sep.,2006 to Jul.,2013,we transferred the velocity recording spectrum into hypocenter displacement spectrum by geometry diffusion correction,dielectric attenuation correction and instrumental correction etc..Then we calculated the corner frequency and zero frequency limit by using genetic algorithm and obtained the source parameters of seismic moment and rupture radius etc.finally.The analysis result of corner frequency characteristic shows that the corner frequency of the earthquake had obvious local difference in Longtan Reservoir of Guangxi,the relationship between the corner frequency and seismic moment of C4 earthquake that is near the dam head plexus was not obvious.The closer from the dam area,the consistency of change relationship between corner frequency and water level is stronger on the time,the negative correlation is more obvious and the corner frequency is relatively lower.The ML4.8 earthquake on Sep.18,2010 occurred in the rise stage of corner frequency at the junction of Guangxi Tian'e and Guizhou,but the corner frequency was stable before more than 1 year before the earthquake.