浙江珊溪水库地震震源参数研究

Hypocentral Parameters Research of the Shanxi Reservoir Area in Zhejiang

利用浙江省区域数字地震台网记录的珊溪水库地震波资料,采用Brune(1970)模式,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,使用遗传算法计算拐角频率及零频极限,进而计算震源半径、地震矩等小震震源参数,并系统分析了各种参数之间的关系。研究中使用发生于2002～2006年间ML2.0～4.6珊溪水库库区地震180个,分析结果为:地震矩范围为1011～1015N.m,震源破裂半径为74～727m,地震矩、拐角频率、矩震级及体波震级之间表现出一定的对数线性或半对数线性关系,并可分别表示为:lgM0=0.0061R+11.71,lgM0=1.11ML+10.11,MW=0.7447ML+0.7。地震应力降范围为0.08～4.95MPa,应力降与震源半径之间表现出一定的相关关系。

Using the Brune model （1970） and the seismic data of Shanxi Reservoir recorded by the regional digital seismic station of Zhejiang Province, we transferred the velocity record spectrum into hypocenter displacement spectrum by geometry diffusion correction, dielectric attenuation correction and instrumental correction. The comer frequency and zero frequency were calculated using genetic algorithm. Then hypocentral parameters including hypocentral radius and seismic moment were calculated and the relationships between them were analyzed systematically. The paper studies 180 regional earthquakes with ML 2.0 - 4.6, occurring between 2002 and 2005. The results show that for those earthquakes whose seismic moments are 10^11 - 10^15 N· m and rupture radius are 74 - 727, there are log-linear relationships between seismic moments and comer frequency, seismic moment and bodywave magnitude and semi-log-linear relationships between moment magnitude and body-wave magnitude. They can be expressed： lgM0 = 0.0061R ＋ 11.71, lgM0 = 1.11ML ＋ 10.11, Mw = 0.7447ML ＋ 0.7. The seismic stress drops ranges from 0.08 - 4.95MPa and some correlation shows between stress drop and hypocenter radius.