渤海及其邻区震源机制解特征

Characteristics of Focal mechanisms in Bohai Sea and Its A djacent Areas

通过分析渤海及邻区的震源机制解的特征,发现该区现代构造应力场的主压应力方向为NEE-EW向,主张应力方向为NNW-SN,以水平和近水平应力作用为主。渤海盆地及邻区的地壳破裂以NW-WNW和NNE-NE走向的共轭剪切破裂活动为特征,是现代构造应力场作用的构造基础。震源机制解的系统聚类表明,渤海及邻区的地震主要以走向滑动地震为主,其次为正断层地震,对应该区不同的构造运动。

Based on the analysis of the characteristics of focal mechanisms in Bohai Sea and its adjacent area, it＇s observed that the principal compressive stress axis is in the NEE-EW direction and the principal tensile stress axis in the NNW-SN direction, the tectonic stress fields of these areas are dominated by horizontal and near-horizontal stress. The crustal rupture in Bohai Sea and its adjacent area is characterized by conjugate shear rupture activity in directions of NW- WNW and NNE-NE, which forms the tectonic foundation of modem tectonic stress field. Results of hierarchical clustering of focal mechanisms show that earthquakes in Bohai Sea and its adjacent area are mostly strike-slip earthquakes, followed by normal fault earthquakes, which correspond to different tectonic movements.