In reflection shallow seismic exploration, bad traces in common shot gather can be identified and removed by quantifying their properties. The relevant properties include: (1) the amplitude of ta trace in some window; (2) the decrease in amplitude as time increases; and (3) the average period of a trace over some window. In general, using each individual property alone only identifies some of the bad traces. However, using all three properties combined identifies almost all them. Therefore, a computer program can be coded to remove most of the bad traces, thereby largely reducing the need for human intervention.