Transcripts of travelTimeTutorial We're going to calculate the P wave travel time for station BFO. I gave you in the problem set the origin time of the earthquake. Here it is. If you were following along with the last video, you know that we picked the arrival time for BFO as 1:38:12. All we have to do is subtract the origin time from the arrival time and we get the travel time of the P wave. When you are subtracting time you have to remember that there are 60 seconds in a minute and 60 minutes in an hour, and not 100. I know you are laughing but someone gets this wrong every time, so I'm going to go through this anyway. Since we can't subtract 32 from 12 we are going to borrow a whole minute and change 12 to 72. So when we subtract we get a minute and 40 seconds. Sometimes I just like to convert this to seconds, so that's 100 seconds. It makes plotting easier later on, but I'll leave that up to you.