敖汉旗地区震群精定位及其空间分布特征

以敖汉旗地区震群作为研究对象,选取内蒙古测震台网2018—2019年的震相观测报告,分别利用单纯型定位法、Hypo2000定位法和双差定位法对其进行重定位和对比分析。结果显示,双差方法的定位精度最高。根据双差方法定位结果,敖汉旗的震群在赤峰?开源断裂的南北两侧均有1个集中分布区,2个区域的震源深度范围均为4～12km;其中,73%的地震位于断裂北侧,震中位置沿NW?SE向呈条带状展布,延伸长度约6.8km,震源深度由西向东逐渐变深、由南向北逐渐变深再变浅;而断裂南侧的地震其震中位置聚集呈簇状,SN向最大扩展长度约0.98km,震源深度无明显沿EW或SN方向的变化特点。敖汉旗震群的精定位结果与对该序列地震空间分布特点的认识,可为该地区发震构造的研究与三维精细速度结构的建立提供更为精确的震源参数与参考依据。

Relocation and Spatial Distribution Characteristics of the Aohanqi Earthquake Sequences in Inner Mongolia Autonomous Region

Taking the Aohanqi earthquake sequences as a case study, the seismic phase observation report of Inner Mongolia between 2018 and 2019 are used to relocate and analyze Aohanqi earthquake sequences by applying Hypo2000 location method as well as double difference location method respectively. It was concluded that the double difference location method has relatively higher locating accuracy among others. According to the results of double difference location method, the Aohanqi earthquake sequences has two concentrated distribution area which is located separately on the north and south sides of the Chifeng-Kaiyuan fault. About 73% of the earthquake is on the north side of the fault, and the epicenter is distributed in a strip along the NW-SE direction with an extension length of about 6.8km. The focal depth gradually became deep from west to east, and gradually became deep to shallow from south to north. However, the epicenter of the earthquakes on the south of the fault is clustered, with a maximum extension length of about 0.98km from south to north, and the focal depth showed no obvious variation along the east-west or north-south direction. The precise location results and the better understandings of the spatial distribution characteristics of the Aohanqi earthquake sequences can provide more accurate source parameters and references for the study of the seismogenic structure and the establishment of three-dimensional fine velocity structure in the region.