L and subsidence in Shanghai (1) 19211926193119361941194619511956196119661971197619811986199119962001 -500 -1000 60 -1500 -80 -2000 -100 一Accumulative(m) Annual average(mm） -2500 120 Land subsidence in Shanghai （1） 1921 1926 1931 1936 1941 1946 1951 1956 1961 1966 1971 1976 1981 1986 1991 1996 2001 -120 -100 -80 -60 -40 -20 0 20 -2500 -2000 -1500 -1000 -500 0 Accumulative(mm) Annual average（mm）