澄江5.2级地震的震源机制、震源应力场和震源断层

The Source Mechanism, Source stress Field and Source Fault for the Chengjiang Earthquake of M5.2

利用地震波资料对澄江 5 2级地震序列的震源机制、震源应力场和震源断层作了分析研究。结果表明 ,整个序列发展过程中 ,震源区及附近 ,构造应力场以南东东方向、水平作用为主的压应力场为主。其次还有南南东向、水平作用为主的压应力场的作用。由序列震源机制解分析 ,主震发震断层是走向北北东 ,倾角较陡的断层面 ,在南南东—南东向 ,接近水平的压应力场作用下 ,该断层面具有以左旋走滑为主的错动性质。该断层面是序列的主破裂面。在序列发展过程中 ,北西西—北西向断层也参与了活动。有的余震 ,虽然发生在与主破裂面一致或接近的断层面上 ,但破裂错动的旋性发生了变化 ,出现了相对主破裂事件的反向错动。极少数余震破裂错动性质呈现出以倾向滑动为主的特征。在序列发展过程中 ,破裂面及其错动性质显著地复杂。由于强震的发生 ,主破裂的错动 ,使得震源区局部应力场状态错综复杂。

The source mechanism, source stress field and source fault for the Chengjiang earthquake of M5.2 has been analyzed by the data of seismic waves. The results show that the SNN tectonic stress field with horizontal action of compression in the source area and nearby acts as the major in the whole development of the sequence. The second is the SSE compression stress field with horizontal action as the major. It is analyzed from the sequence source mechanism solution that the major earthquake fault strikes in NNE with a steeper fault plane. Under an action near horizontal compression stress field in SSE-Se, the fault plane has a property of left-lateral strikeslip, which is the main fracture plane of the sequence. During the process of the sequence, the NWW-NW fault also participates in the action. Although some of the aftershocks occurred in the fault plane identical with or near the major fracture plane the rotation property of the fracture and dislocation had been changed, appearing an opposite dislocation relative to the main fracture. The dislocation property of the fracture for very few aftershocks shows the characteristics of inclineslip. In the process of the sequence, the fracture plane and dislocation property is very complicated. Due to the occurrence of the strong earthquake, the dislocation of the main fracture makes the state of the local stress field in the source area very complicated.