2008年6月10日内蒙古鄂伦春自治旗M5.2地震的震源机制、震源深度和发震构造

2008年6月10日14时5分,内蒙古鄂伦春自治旗发生M5.2地震,该地震处于大兴安岭梯度带北段,是内蒙古东北部地区近年来发生的最大地震。基于内蒙古地震台网观测资料,使用TDMT方法、CAP方法、PTD方法和sPn-Pn等方法测定此次地震的震源机制解和震源深度。结合已有数据资料,分析震源区域地震的时空分布特征和构造应力特征,并探讨该地震的发震构造。此次地震震源深度较浅,位于上地壳,结合震源机制解结果、地震分布特征和构造背景分析认为,此次地震为右旋走滑类型,走向NNE,主压应力方向为SWW。

Focal Mechanism, Focal Depth, and Seismogenic Structure of Oroqen M5.2 Earthquake Occurring on 10 June, 2008

The M5.2 earthquake that occurred in Oroqen on 10 June, 2008, was the largest earthquake effecting northeastern Inner Mongolia in recent years. In this study, the focal mechanisms and focal depth of this earthquake are determined using the TDMT method, CAP method, PTD method, and sPn-Pn method. Results using the CAP and TDMT methods are inconsistent with each other, and show that the focal depth of the earthquake is shallow and that the source is located in the upper crust. Combined with existing data, the spatial and temporal distribution characteristics and tectonic stress characteristics of earthquakes in the area near the epicenter of this earthquake are analyzed, and the seismogenic structure of this M5.2 earthquake is discussed. Using a combination of the focal mechanism solution, earthquake distribution characteristics, and tectonic background, the M5.2 earthquake is determined as a dextral strike-slip faulting event with a NNE strike and a SWW principal compressive stress direction. The seismic activities of earthquakes in this area were significantly enhanced after the M5.2 earthquake. Focal mechanism solutions in the northern section of the Greater Khingan Range gradient zone show that the Greater Khingan Range fracture is controlled by NEE-SSW horizontal compressional stress, with a strike-slip feature.