河西地区重力变化与2013年门源MS5.1地震研究

Study on the Gravity Variation in Hexi Area and the MenyuanMS5.1 Earthquake

摘要:

基于2010年5月—2013年10月的6期在河西地区流动重力测量资料获得的重力场时空变化结果，分析该区近期重力场变化及与2013年门源MS5.1地震的关系。结果表明：河西地区重力场变化空间分布显示在活动断裂附近重力变化较大，沿祁连山北缘断裂、昌马—门源断裂及庄浪河断裂形成与断裂带走向基本一致的重力变化高梯度带，反映了断裂构造活动引起的重力局部异常变化特征。2013年门源MS5.1地震发生在重力变化的高梯度带附近。

Abstract:

To study the relationship between gravity field variation and earthquakes， this study analyzes the relationship between gravity field variation in the Hexi area and the MS5.1 earthquake area near Menyuan in 2013 on the basis of gravity field variations obtained through mobile gravity observation in the Hexi area from May 2010 to October 2013. On the basis of gravity change in the Hexi area during the study period，the accumulated gravity change in a longer period is applied using the line from Minle to Tianzhu in the northern Qilian Mountain as a borderline of positive and negative gravity.The gravity change is positive in the Hexi Corridor north of the borderline and negative in the Qilian Mountain area south of the line. In the north and south region of the borderline，the accumulated gravity variation changes sharply from positive to negative.Moreover，a high gradient belt of gravity change located on the North Qilian Mountain Fault is formed between Tianzhu and Minle，and the accumulated gravity positive change is up to 70 × 10-8 ms-2 in the northern region.The accumulated gravity change forms two negative extreme value zones in E’bao and Tianzhu，where the minimum is -70 × 10-8 ms-2，and a negative depression zone is formed between Tianzhu and E’bao，where the 2012 MS4.9 and 2013 MS5.1 earthquakes near Menyuan occurred.The results shows that the gravity field variation is larger near the active faults in the Hexi area，including the Qilianshan North Rim Fault located between E’bao，Menyuan，and Gulang，and the Changma-Menyuan and Zhuanglang River faults. Moreover，a high gradient belt of gravity variation in these regions is consistent with these faults.The Menyuan MS5.1 earthquake occurred between E’bao and Menyuan near the high gradient zone of gravity variation.The gravity variation shows the local gravity anomaly characteristics caused by fault tectonic activity.