Question

seismograph a records p waves at 6:05 pm and s waves at 6:10 pm. Seismograph b records p waves at 6:10 pm and s waves at 6:25 pm. What is the difference in the arrival times at each device? Which device is closer to the earthquake's epicenter?

Answer 1

For seismograph A, the lag time is
5 minutes (difference between 6:10 and 6:05)
For seismograph B, the lag time is
15 minutes (difference between 6:25 and 6:10)

Assuming that earthquake waves have a constant velocity during the earthquake, then the seismograph with the shorter lag time is closer to the epicenter. So,
Seismograph is closes to the earthquake's epicenter