利用2008年1月1日—2021年12月31日发生在蒙冀辽交界地区的472个地震的P波初动符号资料,应用综合震源机制解法获得了蒙冀辽交界地区0.25°×0.25°精细应力场,所得应力场结果基本覆盖整个蒙冀辽交界地区。应力场反演结果显示: ①蒙冀地区受拉张应力体系作用,主压应力场为东向,源自青藏高原东北边缘的强烈挤压作用。综合震源机制解类型主要为正断层和走滑型,P轴整体呈NE、NNE向,T轴整体呈NW或NNW方向,与前人研究该区域活动构造运动和地块受拉张和裂陷作用相符合。②蒙辽交界地区P波矛盾比较大,震源机制界面较为散乱,蒙辽或冀辽交界地区辽宁一侧震源机制解以逆断层为主,辽南地区震源机制以正断性质为主。

Based on the initial P-wave signal data from 472 earthquakes occurring in the Inner Mongolia-Hebei-Liaoning border region between January 1, 2008, and December 31,2021,a fine-grained stress field with a resolution of 0.25°×0.25° was constructed using the comprehensive focal mechanism method. This stress field effectively covers the entire Inner Mongolia-Hebei-Liaoning border area. The results of the stress field inversion reveal the following: ① The main compressive stress field in the Inner Mongolia-Hebei region trends eastward,driven by a tensile stress system resulting from the intense compression along the northeastern margin of the Qinghai-Tibet Plateau. The dominant focal mechanism solutions are normal faulting and strike-slip faulting,with the P-axis generally oriented northeast to east-northeast, and the T-axis oriented northwest to west-northwest. These findings are consistent with previous studies on active tectonic movements and block tension and rifting in the area. ② In the Inner Mongolia-Liaoning border area,there is greater variability in the P-wave data,and the focal mechanisms are more dispersed. In the Inner Mongolia-Liaoning or Hebei-Liaoning border regions,the seismic source mechanisms are predominantly reverse faults,while in southern Liaoning,normal faulting is more prevalent.

P315

内蒙古自治区地震局局长基金(2022(ZD) TM02、2023MS09)、内蒙古自治区自然科学基金(2023LHMS04006)共同资助