Abstract: The long period microtremor observation was performed on soft soil area in Shanghai city. The FFT spectrum analysis and H/V method were used to evaluate the spatial variations of long period microtremor and its spectrum stability and clarify the depth of deposits and its horizontal distributions. Comparing the inversion results with the known borehole data, the signal of long period microtremor is good and it is very appropriate to deeply expand the investigations in Shanghai city,the signal of microtrmor in the long period area is steady; the peak of H/V spectrum is obvious and shows regular variation characteristic which reveals the depth of soil in Shanghai city is between 200 m and 300 m.

Key words: long period, microtremor, observation, horizontalvertical (H/V) spectrum analysis