Reading Seismograms

[kat09]

I'm doing a ScienceBuddies project that involves reading seismograms to find the epicenter of an earthquake. I can't really tell where the S-wave starts on the seismogram, though. Or, rather, I can't tell whether large jumps in the seismogram (there usually seem to be only one) are S-waves or surface waves, and my times seem to be getting mixed up and unproportional. Does anyone have advice for differentiating between them?

[tdaly]

Hi kat09,

One option would be to do everything based on the P wave travel times. The first spike on the seismogram will be the P wave. This will be lower amplitude than the S wave, but it might be easier for you to identify.

Another option would be to try looking at the seismogram from another station, which might record the S wave more distinctly from the P wave. If the station you are looking at is quite close to the epicenter of the earthquake, then the P wave and S wave will arrive at the seismometer very close together. That would make it difficult to identify the S wave.

I would suggest going with the first option and using only the P wave arrival times. Let me know how that goes, and post back with any other questions you might have.