河南范县M_L4.3地震前后的重力场变化与预报过程

Short-term Change of Gravity Field before and after Fanxian M_L4.3 Earthquake in Henan the Prediction Process

讨论了2005年4月27日范县ML4．3地震前后重力场的变化：自2003年5月经历了趋势下降→转折上升→变化加速，地震发生在加速变化过程中。部分测点点值、测段段差值的趋势性异常在持续相当长时间后变化幅值在（30～60）×10^8m·s^-2之间。震后该区的重力异常没有恢复。重力变化可能是由该区地壳形变、地壳深部质量迁移和断层蠕动共同作用引起的。介绍了根据重力异常预报地震的过程。

The variation feature of gravity field and seismicity before and after Fanxian ML4. 3 earthquake discussed. Since May in 2003, the gravity field showed a tendentious descent-ascentaccelerative ascent style, and the earthquake occurred in accelerative change stage. After the tendency anomalies of point-value at some measuring stations and of segment-value of measuring segment lasted a considerable time, the variation amplitudes were（30～60） × 10^-8m · s^-2. After the earthquake the gravity anomaly in this region did not recovered. Variations of gravity field in this area may be caused by the earth crust deformation, quality transition in deep crust and fault creep deformation. Meanwhile the earthquake prediction according to the gravity anomalies is in- troduced.