新疆天山地区强震前地震条带不清晰的原因初探

Preliminary Research on the Reason of Unclear Seismic Belt Before Mid-strong Earthquakes in Tianshan Mountain Area, Xinjiang Uyger Autonomous Region

摘要:

新疆地区在强震前地震条带不明显。本文对比分析了新疆天山与川滇地区区域构造背景和地震震源机制解,得到:①新疆天山地区区域地震构造以逆冲型为主,而川滇地区区域地震构造以走滑型为主。②1970年以来的天山地区中强地震以逆断层和走滑型地震类型为主,走滑型地震多数包含较大的倾滑分量;而川滇地区6级强震以走滑型地震类型为主,地震主要以水平错动为主。认为弱震条带适用于以水平剪切错动为主的地震,而新疆天山地区地震倾滑分量较大,因此中强地震前弱震条带图像不清晰,中短期地震预报意义不显著。

Abstract:

The seismic belt before mid-strong earthquakes in Xinjiang Region is not clear. For this problem, the regional structure background and focal mechanism solutions of Tianshan Mountain area in Xinjiang are contrasted and analyzed with that in Sichuan and Yunnan provinces. The result shows： （1） The regional earthquake structures in Tianshan Mountain area are mainly thrust faults, while ones in Sichuan andYunnan area are mainly strike-slip faults. （2） Since 1970, the focal mechanism solutions of mid-strong earthquakes were mainly reverse and strike-slip types in Tianshan Mountain area, and most of the strike-slip events contained lean components. While ones of Ms6 strong earthquakes area were mainly the strike-slip types in Sichuan and Yunnan area, and the lean component were very small, mainly showed horizontal movement. The weak seismic belts should be applied to earthquakes which are horizontal shear movement in focal mechanism solution. Since the lean components of earthquakes were big in Tianshan Mountain area, the images of the seismic belt before mid-strong earthquakes were vague, and its significance for the earthquake forecast of mid-short term is not good.