Thread: Question about data procession

Hello,I am a student who want to use the data from IRIS to know the changing of velocity of earthquake wave. After installed the software, irisFetch.m, I got a waveform(as attached) according to the example, but I can't understand the meaning of vertical axis. Another queation is that the data recorded by seismograph is the velocity of earthquake wave or displacement?Looking forward to your reply. Thank you very much.
Sincerely yours,Jeffrey