Seismic Wave Travel Time Concepts

The video tutorial explains how to locate an earthquake's epicenter using travel and arrival times of seismic waves. It covers the difference between these times, how to calculate the epicenter distance using graphs, and how to determine the earthquake's origin time. The tutorial also includes a section on analyzing seismograms to extract relevant data.

What is the difference between travel time and arrival time of seismic waves?

• Travel time is the clock time it reaches the station; arrival time is the duration from wave generation to arrival.

• Travel time and arrival time are the same.

• Travel time is the duration from wave generation to arrival; arrival time is the clock time it reaches the station.

• Travel time is when the wave is generated; arrival time is when it reaches the station.

How can you determine the epicenter distance using seismic wave data?

• By calculating the difference in arrival times of P and S waves.

• By observing the color of the waves on the graph.

• By counting the number of waves recorded.

• By measuring the amplitude of the waves.

Why do S waves have a longer travel time compared to P waves?

• S waves travel faster than P waves.

• S waves travel slower than P waves.

• S waves are generated later than P waves.

• S waves are not recorded by seismographs.

What is the first step in calculating the origin time of an earthquake?

• Multiply the travel time of P waves by the arrival time.

• Add the travel time of S waves to their arrival time.

• Divide the travel time of S waves by the arrival time.

• Subtract the travel time of P waves from their arrival time.

If the P-wave travel time is 4 minutes, what is the origin time if the arrival time is 10:04:20?

• 10:00:20

• 10:08:20

• 10:00:00

• 10:04:00

In the example provided, what is the epicenter distance if the lag time is 3 minutes and 20 seconds?

• 1,000 kilometers

• 4,000 kilometers

• 2,000 kilometers

• 3,000 kilometers

What is a seismogram?

• A device that generates seismic waves.

• A written record produced by a seismograph.

• A graph showing the epicenter location.

• A map of tectonic plates.

How is the lag time between P and S waves calculated?

• By adding their travel times.

• By subtracting the S-wave arrival time from the P-wave arrival time.

• By dividing the S-wave travel time by the P-wave travel time.

• By multiplying their travel times.

What is the significance of the lag time in determining the epicenter distance?

• It helps in identifying the type of earthquake.

• It is used to calculate the distance to the epicenter.

• It determines the magnitude of the earthquake.

• It is irrelevant to epicenter calculations.

What should you do if you make a math error while calculating seismic data?

• Ignore it and move on.

• Use a calculator to avoid errors.

• Recalculate and verify the results.

• Ask someone else to do it for you.