Determining Epicenter Distance from Seismograms

What does the initial jump in a seismogram indicate?

• Malfunction of the seismometer

• Arrival of the S-wave

• End of the earthquake

• Arrival of the P-wave

What is the purpose of calculating the lag time in seismology?

• To measure the earthquake's duration

• To predict future earthquakes

• To find the distance to the epicenter

• To determine the earthquake's magnitude

How is the lag time between P-wave and S-wave calculated?

• By using a global positioning system

• By adding their arrival times

• By measuring the amplitude difference

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

What does aligning scrap paper on the travel time axis help determine in the wedge method?

• The magnitude of the earthquake

• The distance to the epicenter

• The depth of the earthquake

• The duration of the earthquake

Why is the method called 'The Wedge Method'?

• Because of the wedge-shaped graph used

• Because it was developed by Dr. Wedge

• Because it involves wedging paper between travel curves

• Because of the triangular calculations involved

What is the distance to the epicenter if the lag time is 7 minutes?

• 5,400 km

• 7,000 km

• 4,800 km

• 6,200 km

What is the primary use of the reference table in the wedge method?

• To find the distance to the epicenter based on lag time

• To calculate the speed of seismic waves

• To determine the type of seismic waves

• To record the time of earthquake occurrence

How does the wedge method utilize the lag time to find the epicenter distance?

• By comparing it to historical data

• By calculating the speed of the waves

• By plotting it on a graph against magnitude

• By aligning it with travel curves on a reference table

In reverse calculation, what does knowing the distance to the epicenter help determine?

• The lag time between P-waves and S-waves

• The time of the earthquake

• The magnitude of the earthquake

• The depth of the earthquake

If a seismic station is 2,000 km from the epicenter, what would be the approximate lag time?

• 5 minutes

• 3 minutes and 20 seconds

• 2 minutes and 45 seconds

• 4 minutes and 10 seconds