新疆于田及周边地区地震活动性与重力异常特征

基于最新重力场模型对2014年于田M_s7.3地震震区的重力异常特征进行分析, 并应用Crust1.0地壳模型计算得到震区的深部构造形态, 结果显示: 震中位于地壳厚度陡变带上.同2008年于田M_s7.3地震相比, 震中虽位于不同位置, 但发震机制均与深部地壳结构变化密切相关.统计研究区内历史地震活动性与重力异常之间的关系, 发现震中的自由空气异常与地形存在明显的线性相关性, 而布格异常和均衡异常的结果则明显不同.进一步地分别计算不同重力异常的水平总梯度和线性信号, 结果表明: 重力异常梯度量与地形的相关特性更明显.研究表明: M_s7.0以上大震活动与重力异常之间具有明显的统计特性学, 这可能与重力异常反映的深部结构和壳内质量分布的不均匀有关. 

Seismic Activity and Gravity Anomaly Characteristics of Yutian in Xinjiang and Surrounding Regions

The latest model of the gravitational field was used in the analysis of the gravity anomaly characteristics in the Yutian seismic zone and surrounding regions. The layered crustal structure model (Crust1.0) has been applied to obtain the deep tectonic structure around the seismic zone. This epicenter occurred in the steep variations of the crustal thickness. Contrast to the M_s7.3 earthquake in 2008 in this region, although these two epicenter were located in different 3-D spaces, they are closely related to the changes in the deep crustal structures. Besides, based on the statistical analysis of the relationship between the seismicity of historical earthquakes (M_s≥5.0) and three different gravity anomalies, we found that the free-air gravity anomalies in the seismic zone are in an obvious linear correlation to the topography, while the Bouguer anomaly and isostatic anomaly are distinctly different with the topography. In addition, the total gorizontal gradient (HGM)of the anomalies were calculated and the analytical signal (ASL) was plotted, which suggest that the gradient values are more distinctly correlated. The results show that a significant statistical characteristic exists between the activities of the strong earthquakes (M_s≥7.0) and the gravity anomalies, which may be related to the mass uneven distribution of the deep structure which caused the gravity anomaly.