Wave field continuation can remove much of the energy which propagates along the surface, such as direct waves, ground roll and some random noises.
把波场沿深度外推可以消除与地表有关的“噪音” ，如直达波、面波、声波及在表层传播的随机噪音。
2
To compute the mean of many time shift values by shifting time window can help to eliminate the interference of random and other noises with surface factor, thus lineup statics may be obtained.
The complexity of surface secondary noises lies in the following five aspects: (1)The secondary noises may occur on the whole record and they can be neither avoided nor removed.