渤海地区是我国东部地震较为活跃的地区之一,历史上强震频发,曾被列为地震重点危险区,其震情备受关注。近期该地区有感地震多发,因此有必要深入了解这些地震的震源破裂性质,同时探究渤海地区现代构造应力场分布,以期为后续判识地震危险性研究工作提供科学参考。本文基于前人对渤海地区震源机制解的研究结果,采用波形反演方法计算并补充完善了2010—2022年M≥3.5地震的震源机制解,使用MSATSI软件包反演计算区域构造应力场。结果表明,渤海海域近期地震事件以走滑型为主,其次为正断型,与地震事件附近主要断裂带的运动学特征具有较好的一致性;区域构造应力场的优势方位为NEE向,与华北地区构造应力场基本一致,整体相对稳定,局部存在一定差异,这与海域地震数量较少且分布不均有关,另外应力形因子R值相对较小,区域地壳应力以张应力为主。

The Bohai area is one of the relatively active regions in eastern China,with frequent strong earthquakes in history,which has been classified as a key earthquake-prone region,and its seismicity draws much attention. Recently,there have been many felt earthquakes. Therefore,it is critical to understand the focal rupture features of those earthquakes and investigate the distribution of the modern tectonic stress field to provide scientific reference for estimating the future earthquake risk. In this paper,we use the waveform inversion method to calculate the focal mechanism solution of the M≥3.5 earthquakes from 2010 to 2022 to supplement related data based on the results of previous research and invert the regional tectonic stress field with the MSATSI software package. The results suggest that the recent events are mainly the strike-slip mode,followed by the normal faulting,which is consistent with the kinematic features of the main fault zone nearby. The dominant orientation of the regional tectonic stress field is NEE,which is consistent with the regional tectonic stress field in North China. The overall stress field is relatively stable,and there are some local differences in the locality,which is related to the small number of earthquakes and the uneven distribution in the sea area. Furthermore,the shape factor R-value is relatively low,indicating the regional crustal stress is dominated by tensile stress.

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