The focus of an earthquake is
 a point on the earth's surface where the initial release of seismic energy occurs.
 a point on the earth's surface where seismic waves are reflected downward.
 a point within the earth where seismic waves are reflected upward.
 a point within the earth where seismic waves are reflected downward.
 *a point within the earth's surface where the initial release of seismic energy occurs.

The epicenter of an earthquake is
 *a point on the earth's surface directly above the initial release of seismic energy.
 a point within the earth's directly beneath the initial release of seismic energy.
 a point on the earth's surface where the initial release of seismic energy occurs.
 a point within the earth where the initial release of seismic energy occurs.
 none of the above.

Which of the following seismic waves has the same waveform as a sound wave?
 surface wave
 *P wave
 S wave
 L wave
 none of the above

Which of the following seismic waves is the first to arrive at a seismic station?
 surface wave
 *P wave
 S wave
 L wave
 none of the above

Which of the following seismic waves is the last to arrive at a seismic station?
 *L wave
 P wave
 S wave
 body wave
 none of the above

Which of the seismic waves vibrates side-to-side relative to its direction of propagation?
 surface wave
 P wave
 *S wave
 L wave
 none of the above

The two kinds of body waves are
 surface waves and P waves.
 L waves and P waves.
 *P waves and S waves.
 surface waves and S waves.
 L waves and S waves.

The following seismic waves are used to locate earthquake epicenters:
 surface waves and P waves.
 L waves and P waves.
 *P waves and S waves.
 surface waves and S waves.
 L waves and S waves.

The clocks at seismic stations in the United States are set at
 Eastern Standard Time.
 Central Standard Time.
 Southern Standard Time.
 Pacific Standard Time.
 *none of the above.

Which of the following statements is correct?
 P-wave amplitude is larger than the S-wave amplitude.
 *S-wave amplitude is larger than the P-wave amplitude.
 P-wave amplitude and S-wave amplitude are about the same.
 P-wave amplitude is larger than all the other seismic waves recorded on a seismogram.
 S-wave amplitude is smaller than all the other seismic waves recorded on a seismogram.

Determining the distance along the earth's surface from a seismic station to the epicenter of an earthquake is based upon
 *the difference in arrival times between the first P wave and the first S wave.
 the difference in arrival times between the first P wave and the first L wave.
 the difference in arrival times between the first S wave and the first L wave.
 the difference in arrival times between all three seismic waves.
 none of the above.

To locate the epicenter of an earthquake, it takes
 one seismic station.
 at least two seismic stations.
 *at least three seismic stations.
 at least four seismic stations.
 no seismic stations.

<i>The following questions are based on the three seismograms in Figure 3.4, as well as the travel-time curves in Figure 3.2.</i>
The arrival time for the first P wave at Station X is
 *8:07:30.
 8:09:30.
 8:11:30.
 8:13:30.
 8:15:30.

The arrival time for the first S wave at Station X is
 8:07:30.
 8:09:30.
 *8:11:30.
 8:12:30.
 8:15:30.

The difference between the P-wave arrival time and then S-wave arrival time for Station X is
 3<sup>1</sup>/<sub>2</sub> minutes.
 *4 minutes.
 4<sup>1</sup>/<sub>2</sub> minutes.
 5 minutes.
 5<sup>1</sup>/<sub>2</sub> minutes.

The distance to the earthquake epicenter from Station X is approximately
 500 miles.
 *1500 miles.
 2000 miles.
 2500 miles.
 3000 miles.

The arrival time for the first P wave at Station Y is
 8:06:30.
 *8:08:30.
 8:10:30.
 8:11:30.
 8:13:30.

The arrival time for the first S wave at Station Y is
 8:06:30.
 8:08:30.
 8:10:30.
 8:11:30.
 *8:13:30.

The distance to the earthquake epicenter from Station Y is approximately
 1450 miles.
 1800 miles.
 *2250 miles.
 2600 miles.
 3000 miles.

The arrival time for the first P wave at Station Z is
 8:07:30.
 *8:09:30.
 8:11:30.
 8:12:30.
 8:15:30.

The arrival time for the first S wave at Station Z is
 8:07:30.
 8:09:30.
 8:11:30.
 8:12:30.
 *8:15:30.

The distance to the earthquake epicenter from Station Z is approximately
 1200 miles.
 1600 miles.
 2000 miles.
 2400 miles.
 *2800 miles.

<I>Using the data obtained from the three seismograms and the travel-time curves, scale the epicenter distances using the map scale provided, plot the epicentral circles, and locate the earthquake epicenter on Figure 3.5.</I>
The epicenter is......(NOTE: The  center of the map would be the intersection of two corner-to-corner diagonal lines)
 northwest of the center of the map.
 *northeast of the center of the map.
 southwest of the center of the map.
 southeast of the center of the map.
 right on the dead center of the map.

Using the data obtained from seismogram X and the time-travel curves, determine the time of origin of the earthquake.  The time of origin is
 7:58:30
 8:00:30
 *8:02:30
 8:04:30
 8:06:30

Using the data obtained from seismogram X and the time-travel curves, determine the arrival time for the L-wave at Station X.  The L-wave arrival time is
 8:15:15
 *8:17:15
 8:19:15
 8:21:15
 8:23:15