VARIATIONS OF GRAVITY FIELD BEFORE AND AFTER TAIYUAN M_L5.0 EARTHQUAKE

The gravity field in Shanxi surveying region changed obviously before and after Taiyuan M_L5.0 Earthquake occurred on Sep.3, 2002.Before this event, from Dec.of 2001 to Jun.of 2002, the gravity field showed an pattern:ascent-descent-ascent and quiet-active-quiet.After the tendency anomaly lasted a period of time, the observing value on some sites turned in March, 2002, and accelerated in June.The variation of site value and segment difference was between 30×10^-8m·s^-2 to 60×10^-8m·s^-2, and the earthquake occurred in the period of acceleration.After the earthquake, the gravity anomalies recovered gradually.The Variation of gravity field in this area may be caused by the crustal deformation or deep transference and fault creep.