在我国大陆开展的流动重力重复观测是监测地震前兆异常的主要技术手段之一.对大地震前流动重力场观测资料研究结果表明,区域性持续的重力场增加和减少与大地震发生有显著关系.目前,区域重力场变化监测已经成为一种常规前兆观测技术手段.本文首先从三维倾斜台阶模型人手,计算了理论重力异常,并对异常进行变换,找到了一种可以更好刻画其场源边界的方法,并进一步应用空间相关系数法进行异常特征分析,得到了从概率意义上估计危险区的方法.最后,本文尝试运用此方法对青藏高原东缘地区1998-2005年的四期流动重力测网资料进行处理和分析.应用本文提出的异常处理技术,可有效地圈定异常梯级带位置,确定质源体边界形态,并可以联合背景重力异常场等其他资料,给出危险区发震概率的空间估计,分析结果在年度震情会商中可以有效地对地震危险区的划定提供技术支持.%Repeated mobile gravity observation in China mainland has been one of the main technical means for monitoring earthquake precursors. Researches on mobile observation of gravity field before large earthquakes indicated that continuous variation of regional gravity field (increase or decrease) significantly related with large earthquake occurrences. In this paper, we carried out computation and transformation of theoretical gravity anomalies based on a 3-D tilt model. We found an effective method to determine the boundaries of density anomaly source. Moreover, analysis on the characteristics of the anomalies is based on a spatial correlation coefficient method. We further obtain a probability method to estimate the hazard zone. At last, we process and analyze mobile observations of gravity in eastern margin of Tibet Plateau from 1998 to 2005 by the preceding method. It is found that the location of anomaly gradient zone and the boundary of hypoccntroid can be confirmed effectively. Combined with background gravity field and other information, we can obtain a probability estimate of earthquake hazard zone, which will be necessary to determine the risk region in annual earthquake consultation.
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