2.Current status and main features 250 200 150 50 195919621965195819711874197719801983198619891992 1995 Fig2.Variation of the annual land subsidence at BM Bu 435(a long-term monitoring point in Tanggu,Tianjin)from 1959 to 19972. Current status and main features Fig2. Variation of the annual land subsidence at BM Bu 435 (a long-term monitoring point in Tanggu, Tianjin) from 1959 to 1997