An earthquake emits both S-waves and P-waves which travel at different speeds through the Earth. A P-wave travels at 9 000 m/s and an S-wave travels at 5 000 m/s. If P-waves are received at a seismic station 1.00 minute before an S-wave arrives, how far away is the earthquake center?
A) 88.9 km
B) 1 200 km
C) 675 km
D) 240 km
E) 480 km

Question

Quizplus · Accepted Answer

Let the distance between the seismic station and the earthquake center be "d".
Then, time taken by P-waves to travel from earthquake center to seismic station = d/9000
Time taken by S-waves to travel from earthquake center to seismic station = d/5000
Given that P-waves arrive 1 minute earlier than S-waves.
Therefore, d/9000 - d/5000 = 1
d = 675000 m = 675 km.

An Earthquake Emits Both S-Waves and P-Waves Which Travel at Different