利用高精度小震资料确定新丰江水库大坝区北西向发震断层  

Determination of the NW-trending faults in Xinfengjiang Reservoir dam by using high-precision small earthquake data

作　　者：刘特培[1] 邵叶[1] 杨选[1] 谭争光[1] 丁原章[1] 

机构地区：[1]广东省地震局,中国广州510070

出　　处：《地震学报》2017年第1期23-33,共11页Acta Seismologica Sinica

基　　金：广东省自然科学基金项目(2006B372010)资助

摘　　要：基于2009—2015年广东省河源市新丰江水库库区高精度定位的地震目录(ML≥1.0),划分出大坝—峡谷区的3个北西向小震密集分布带,并依据成丛小震发生在活动断裂面及其附近的原则,采用模拟退火算法和高斯-牛顿算法相结合的方法,反演了这3个小震密集带相应的断层及断层面参数,包括断层面的走向、倾向、倾角、长度、深度和地理位置,获得了大坝区北西向断裂带相关断层的成分及几何形态.结果显示:3条断层走向为北西—北北西,与大坝—峡谷区走向基本一致,深度为3—12km,均为陡峭的活动断层,其长度不超过10km,在库区应力场作用下均以走滑为主兼少许垂直错动;大坝附近为几条断层端点与断层相切点的汇集区,区域应力易集中于此而成为库区地震最活跃的部位.此外,根据断层反演结果及前人资料,论证了白田—双塘断层为新丰江1962年MS6.1地震的发震构造,并首次发现河源断裂在白田至双塘之间中断了约5km,中断的断裂构造为白田—双塘断层的一部分.Based on the ML≥1. 0 earthquake catalogue of Xinfengjiang Reservotr area in Heyuan of Ouangdong Province during the period from 2009 to 2015, this paper delineates three NW-trending small earthquake dense zones in dam- gorge region. According to the principle that the small earthquake clustering occurs in and around active fault plane, this paper calculated the fault plane parameters of the three dense zones including the strike, dip, dip angle, length, depth and geographic position by using both simulated annealing algorithm and Gauss-Newtonian nonlinear inversion algorithm, and finally got the geometric shape of the NW-trending faults. The results show that the three faults are NW-NNW trending in the depth range of 3-12 km, and are of left-lateral strike-slip with a little vertical slip component. Furthermore, the analyses of inversion results combined with previous data indicate that, the Baitian- Shuangtang fault, one of the three NW-trending faults, was proved to be the seismogenic fault of Ms6. 1 Xinfengjiang earthquake in 1962, and from Baitian to Shuangtang, the Heyuan fault is interrupted with gap of 5 km, and the gap is filled with part of the Baitian-Shuantang fault. The junction area of endpoints and tangent points of the three faults intersected near the reservoir dam, which leads to stress concentration more easily there, and becomes the most active seismic region in the reservoir.

关 键 词：新丰江水库 北西向断层 高精度定位小震 断层反演 区域应力场 

分 类 号：P315.2[天文地球—地震学]