Seismic Waves and Earthquakes
Read this summary of Seismic waves and the Richter scale (Links to an external site.). You can ignore the later definitions of "surface" waves. We are only interested in the "body" waves through the Earth:
P for primary (and for "push-pull", i.e. a longitudinal wave), and
S for secondary (and for "sideways", i.e. a transverse wave), which travels slower (and hence arrives later, with a lag time depending on how far you are from the epicenter).
Watch this video which explains how one can find both the distance and the Richter scale magnitude of an earthquake. For this lab you only need to watch the first 2 minutes:
Sample Solution