Regents Earth Science
John Dewey High School
Seismic Wave Travel Times and Epicentral Distances
Reading the Earth Science Reference Tables V
Answer the following questions based on your interpretation of the Earthquake P-Wave and S-Wave
Travel Time chart of the Earth Science Reference Tables (page 11) as well as your class notes.
1. Which generalization about earthquake P-waves and S-waves is correct?
a. When the P-waves and S-waves are near the epicenter they travel at the same speed. b. The speeds of P-waves and S-waves are the same, regardless of the distance traveled. c. P-waves always travel faster than S-waves, regardless of the distance traveled. d. P-waves never travel faster than S-waves.
2. A seismic station recorded an earthquake with an epicentral distance of 4,000 km. If the origin
time of the earthquake was 11:00 am (GMT), at what time did the first P-waves arrive at the seismic station (GMT)? a. 10:53 am b. 11:05 am c. 11:07 am d. 11:12 am
3. How long will an S-wave take to travel from an earthquake epicenter to a seismograph recording
station 6,000 km away? a. 1 min 35 sec b. 7 min 30 sec c. 9 min 20 sec d. 16 min 50 sec
4. Which seismic wave is the fastest, that is, the first to reach (and be recorded) at a seismic
wave recording (seismograph) station? a. P-wave b. S-wave c. L-wave d. Tidal wave
5. A seismograph station recorded the passage of earthquake waves. P-waves arrived but S-waves
did not. The best explanation for the absence of S-waves is that the S-waves a. were never produced by the earthquake. b. stopped when they reached the solid part of the Earth's interior. c. stopped when they reached the liquid part of the Earth's interior. d. travel only along the Earth's surface.
6. Which generalization about P-waves and S-waves is correct?
a. As the distance from the epicenter increases, the speed of both P- and S-waves increases. b. As the distance from the epicenter increases, the speed of both P- and S-waves decreases. c. There is no change in the speed of either P- or S-waves with epicentral distance. d. S-waves are always faster than P-waves.
7. Seismograph station A, located at 2,000 km from an earthquake epicenter, records the arrival
of P-waves at 7:45:00 pm (GMT). Seismograph station B records the P-waves from the same earthquake at 7:49:20 pm (GMT). The distance between stations A and B is a. 2,000 km b. 5,000 km c. 3,000 km d. 500 km
8. Based on the information provided in question 7 above, the origin time of the earthquake was
a. 7:35:00 pm (GMT) b. 7:39:00 pm (GMT) c. 7:41:00 pm (GMT) d. 7:53:00 pm (GMT)
9. Based on the information provided in question 7 above, when should station B expect the
arrival of S-waves? a. 7:41:00 pm (GMT) b. 7:51:00 pm (GMT) c. 7:56:00 pm (GMT) d. 8:08:00 pm (GMT)
10. Based on the information provided in question 7 above, how much time should elapse between
the arrival of P-waves and the arrival of S-waves at station B? a. 4 min 30 sec b. 6 min 40 sec c. 9 min 00 sec d. 13 min 20 sec