Tape 20 results:

Velocity Analysis: 
After noises being removed by pre-processing, we sort data to CMP gathers for velocity analysis. From the initial observation of CMP gathers, we found variations in topography from CMPs 2600 to 3800 which implied complicated geological structures (Fig.  \ref{958509}). First, we tried to do velocity analysis every 50 CMP gathers along the whole line. The front and rear part of this line are fairly flat with little structure changes so it's easy to distinguish events and flat them (Fig.  \ref{450720}), velocities range from 1500 m/s for seafloor to 2000 m/s for deep reflections.