Abstract:
In recent several years, the observed gravity values in the subsidence zone in North China plain have showed rising state compared with that of the same operiod of 1989 and with that in the western Tai-hang mountain area, the accumulated rising quantity in some areas is quite large, for example, it has reached 143×10
-8 m/s
2 in Cangzhou region, 103×10
-8 m/s
2 in Renqiu region, 89-103×10
-8 m/s
2 in Julu-Nangong region. The correction of groundwater decending quantity and ground subsidence quantityhas been made for the varied gravity quantity in some regions, its corrected quantity made up 1/3-1/2 of the varied quantity. After correction, the variational amplitude of gravity values decreased, but some anomalies still existed. Such a relatively large residue variational quantity may contain two factors: one is possibly related with the inherited subsidence of subsidence zone of North China plain and with the structural fault activity in some areas; the other is possibly that the actual ground subsidence quantity is larger than the inferred subsidence quantity.