青海门源M6.4地震前重力场变化特征及其动力机制分析

Characteristics of Gravity Variation and Dynamic Mechanism Analysis in Hexi Area before Qinghai Menyuan M6.4 Earthquake

利用河西地区2011～2015年相对重力资料,研究2016-01-21青海门源M6.4地震前区域重力场时空演变特征及其动力机制。结果表明,河西重力场持续多年正、负交替变化,地震前震中区域负异常持续增强并形成重力变化高梯度带,重力正负差异变化最大达到110μGal。地震发生在重力变化零等值线附近,该等值线分布与祁连山北缘断裂、冷龙岭断裂走向基本一致。

The relative gravity data from 2011 to 2015in Hexi area are processed to analyze the dynamicevolutional characteristics in temporal and spatial domains of the gravity field before the Menyuan M6.4earthquake.The results show that the gravity field alternated wavelike with positive and negative gravity during the study period,which supports that crust tectonics present accumulating strain.The Menyuan M6.4earthquake occurred in the high negative gravity variation area.A high gradient formedin regions,and the positive and negative variations of gravity amount to 110μGal.Specifically,a borderline of positive and negative gravity is located to the south of the epicenter,along the north edge of the Qilianshan and Lenglongling faults.