论文部分内容阅读
珊溪水库地震是近年来发生在少震、弱震的浙江省南部地区的显著地震事件,地震活动表现出分组的间隙性特征,台网定位的地震震中没有显示出分布的优势方向,发震构造不清楚。本研究基于虚波走时方程,将非线性方程线性化,求解获得震源位置及虚波速度初值,之后计算初值走时残差,将走时残差的标准偏差扩大2倍,并据此计算其经度、纬度、深度及虚波速度的最大误差,构造遗传种群,利用遗传算法进行二次定位,获得地震定位的最终结果。利用该方法,对浙江珊溪水库震群进行重新定位,结果表明:本次震群基本上集中发生在一个近垂直、北西向的断层面内,断层面法向与正北向夹角为46°,与正东向夹角为44°,与垂直向夹角为87°。计算小震综合面解获得的结果与定位结果基本一致。震源深度平均4.7km,最大深度9.5km,最浅1.7km,地震震中沿北西向呈狭窄条带状分布,沿北西向地震震源深度趋势性增大,在条带西北端有大约3.5km的地震不连续空段。利用Borun模型计算的小震震源参数结果表明,该震群地震震源参数没有表现出明显有别于构造地震的特征,地震应力降多在0.33MPa左右,平均应力降为0.88MPa,根据应力降空间分布的情况判断,该地震条带西北端地震活动不连续段处于应力降的低值区。
Shanxi Reservoir Reservoir Earthquake is a significant earthquake event occurred in recent years in the southern part of Zhejiang Province, where minor earthquakes and weak earthquakes occurred. Seismicity showed the intermittent characteristics of the subgroups. The epicenter located by the network did not show the dominant direction of distribution. The seismogenic structure Not clear. In this study, based on the travel time equation of the virtual wave, the nonlinear equation is linearized to obtain the initial position of the source and the initial value of the virtual wave velocity. Then the residual of the initial travel time is calculated, and the standard deviation of the travel time residual is expanded by two times, The maximum error of latitude, longitude, latitude, depth and the velocity of the virtual wave, the genetic population is constructed and the genetic algorithm is used for secondary positioning to obtain the final result of the seismic location. Using this method, the relocation of the Zhexu reservoir swarm was carried out. The results show that the earthquake swarm mainly occurs in a nearly vertical and northwesterly fault plane, and the angle between the normal and the normal north of the fault plane is 46 ° , With the positive east angle of 44 °, with the vertical angle of 87 °. Computation of small surface comprehensive solution obtained results and positioning results are basically the same. The focal depth is 4.7km, the maximum depth is 9.5km and the shallowest is 1.7km. The epicenter of the epicenter is distributed narrowly and along the NW direction. The trending depth along the NW-trending seismicity increases with an approximate 3.5km earthquake Discontinuous empty section. The result of Borun model shows that the source parameters of the earthquake swarms do not show obvious characteristics different from the tectonic earthquakes. The stress drop of the earthquake is about 0.33MPa and the average stress is 0.88MPa. According to the stress drop space Distribution of judgments, the seismic belt at the northwestern end of seismic discontinuities in the low-stress zone.