Speed analysis graph plot

[LessandroValente]

I'm processing high-resolution reflection seismic data, trying to find basement rock at around 40m. When checking the speed analysis graph (suvelan), I get a strange plot, I don't know how to explain what must be happening. The data was applied to geometries and organized into cdps. Could anyone help me with this problem? I've already tested several parameters in suvelan, and the graph is still bad. Below is the image I get and the data header.