Question

1. a seismic station receives a p-wave and then an s-wave 30 seconds later. one minute after receiving the s-wave from the first earthquake, it receives a p-wave from a second earthquake. three minutes after the p-wave from the second earthquake arrives at the seismic station, the s-wave from the second earthquake arrives at the seismic station. which earthquake originated closer to the seismic station?

the first earthquake, because the p-wave arrival time and the s-wave arrival time were closer together
the second earthquake, because the p-wave arrival time and the s-wave arrival time were farther apart
the first earthquake, because the p-wave arrival time and the s-wave arrival time were farther apart
the second earthquake, because the p-wave arrival time and the s-wave arrival time were closer together

Explanation:

The time difference between P-wave and S-wave arrival (lag time) increases with distance from the earthquake. For the first earthquake, the lag time is 30 seconds; for the second, it is 3 minutes (180 seconds). A smaller lag time means the earthquake is closer.

Answer:

the first earthquake, because the P-wave arrival time and the S-wave arrival time were closer together