Sometimes you need to see the differences in seismic files
SMSFD does this and more.
You can Add, Subtract, Multiply and Divide files (although multiplication and division are unlikley to see much use)
So it could have been called Seis File Arithmetic, but an acronym of SFA is probably not the best one to use, so I decided on Seis File Difference or SFD.
It also allows for pre and post scalars so that data sets recorded with different parameters can be compared.
It will even compare files from different systems and formats, with the caveat that the number of channels and the sample rates must be the same. If record lengths are different, the shortest is used.
Very easy to use, just select the two files you want to compare, specify the operation, the output file and desired options, click Go and a SEGY result file will be generated.