为了研究大震(Ms≥7)和巨震(Ms≥8)与重力异常和活动断裂的关系.利用EIGEN-6C重力模型计算了相关地区的自由空气重力异常,查阅了相关地区的布格重力异常和活动断裂构造.分析了重力异常突变带和活动断裂带与这些地震的空间分布.发现大震和巨震常在重力异常突变带和活动断裂带交汇处发生.结合前人对地球深部构造特征的研究,提出了一种流变模型来解释大地震发生于重力异常突变带和活动断裂带交汇处的原因:地壳深部流变层(体)流动受阻碍而引起重力异常和能量积累与释放.

In order to find the relationship among a large (Ms ≥7)earthquake,or a giant earthquake (Ms ≥8)and the steepest gradient of gravity field and active fault,the free air gravity anomaly map by EIGEN-6C gravity model was calculated,the bouguer gravity anomaly and active fault of the region trends to occur large or giant earthquake is consulted.The spatial distribution of large and giant earthquakes and active fault,gravity anomaly is analyzed.We come to a conclusion that a large or giant earthquake trends to occur at the intersection area of steepest gradient of gravity field and active fault.With the previous study of deep structures in those area,we propose a rheological model to interpret the regularity.It is that the flow of the rheological layer (body)blocked by the brittle rocks cause the gravity anomaly and energy accumulation and release.

重力场是一个高度叠加的场,任何重力异常都是目标物与其旁侧的和深部的地质体重力异常的叠加,后者即成为目标物重力异常的背景场。重力场的分解和位场转换在重力资料的解释中起到了非常重要的作用。

The gravity field is a highly stacked field, any gravity anomalies are gravity anomaly superimposition of target objects with their lateral and deep geologic bodies, and the latter becomes the background ifeld of object gravity anomaly. It plays a very important role that gravity ifeld decomposition and potential ifeld conversion in the gravity data interpretation.

根据煤田与围岩存在密度差，会引起重力异常的实际情况，本文采用重力法进行煤田勘探，首先分析了重力勘探的可行性，然后在介绍了拉格斯特重力仪工作原理和技术指标的基础上，使用拉格斯特重力仪进行了煤田勘探，研究了煤田重力勘测的工作过程以及对重力异常的校正。

According to the density difference between coal field and the rocks around, it will lead to the actual abnormal situation of gravity. In this paper,the gravity method for coal exploration is used. Firstly, it analyzes the feasibility of gravity exploration, and then based on the Lacoste &. Romberg gravity meter work principle and technical index, it uses L-R gravimeter coalfield exploration to do the research work in coal gravity survey and the gravity anomaly correction.

基于最新重力场模型对2014年于田Ms7.3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Ms7.3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:Ms7.0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.

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 Ms 7.3 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 (Ms ≥5.0)and three different gravity anomalies,we found that the free-air gravity anomalies in the seismic zone are in an obvious linear cor-relation 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 w

利用GRACE重力卫星月重力场数据,通过去相关与高斯滤波等方法获取日本大地震震前震源区周缘年度、季度和年度差分重力变化,以及若干点位时间序列重力变化。分析结果表明:日本大地震前5年内在震源区周边出现了比较明显的卫星重力异常正负交替和迁移现象,至震前1～2年,震区周边形成了明显正负异常区,正重力异常区重力增加现象明显。点位重力时间序列分布指出日本MW9.0级地震前存在与1976年唐山地震类似的重力变化现象。反映出日本大地震震前震源区周边地下物质运动、质量迁移和能量积累等问题。

The decorrelation and Gaussian smoothing method is implemented in GRACE monthly gravity field products to obtain annual and seasonal gravity changes in Japan and its vicinity,as well as time series gravity changes of several points.Results show regional gravity fields in Japan and its vicinity varied from positively to negatively and from area to area in five years before the Japan MW 9.0 earthquake,obviously positive to negative gravity changes were formed in 1~2 years.Time series gravity changes of several points indicate the Japan earthquake displayed the similar time variation gravity phenomenon with the 1976 Tangshan earthquake in China.These results reflect mass migration,mass movement and energy accumulation in Japan and its vicinity before the earthquake occurred.