Identifying features of a seismogram: Teachers' notes

Students identify some features on real seismograms and/or use these seismograms to consider differences in arrival times of P- and S-waves at different stations.

Learning objectives

Students will:

  • identify corresponding points on each of the seismograms for the arrival of the first P-wave and S-wave
  • relate the difference in arrival times of different phases to the relative distances travelled

Notes

This could be done as a whole class using a data projector, as an individual or small group activity using printed versions of the resource sheets.

One side of the resource sheet gives the three seismograms, unmarked, so that students can identify the arrival times of P-waves and S-waves for themselves.

The student activity sheet refers only to the side with the arrival times of P-waves and S-waves marked.

You could ask students to use estimated arrival times and estimated distances to calculate approximate values for the speed of P-waves and S-waves. The values they arrive at will depend on which station they choose: you could use this to discuss the relative effects of errors in estimation for small time differences versus longer time differences, or perhaps to consider whether you would expect the speed of one type of wave to be constant over the three paths.

You might also go on to consider Looking at data from several stations, which show differences in P-wave and S-wave arrival time as a means of estimating distance.

Resources needed

Each group will need: