Locating Earthquake Epicenters and Waves

The video tutorial explains how to locate an earthquake's epicenter using seismogram readings. It distinguishes between the epicenter and the focus, describes the detection of P-waves and S-waves, and demonstrates how to calculate the distance of an earthquake from a seismograph station using time differences. The tutorial further explains how to use circles to determine the earthquake's location and highlights the need for triangulation with three seismograph stations to accurately find the epicenter.

What is the main difference between the epicenter and the focus of an earthquake?

• The epicenter is underground, while the focus is on the surface.

• The focus is the point of rupture, while the epicenter is directly above it on the surface.

• The epicenter is where the earthquake starts, and the focus is where it ends.

• The focus is always closer to the surface than the epicenter.

Which wave arrives first at a seismograph station during an earthquake?

• S-wave

• Surface wave

• P-wave

• Love wave

How is the distance of an earthquake from a seismograph station determined?

• By observing the direction of wave propagation.

• By calculating the time difference between the arrival of P-waves and S-waves.

• By measuring the amplitude of the waves.

• By counting the number of waves recorded.

What tool is used to find the time difference between P-waves and S-waves?

• A protractor

• A compass

• A ruler

• A piece of scrap paper

What is the purpose of drawing a circle around a seismograph station?

• To mark the epicenter of the earthquake.

• To measure the intensity of the earthquake.

• To indicate the area affected by the earthquake.

• To show the possible locations of the earthquake's epicenter.

If an earthquake is 2,600 km away from Rochester, what does this information alone not tell us?

• The depth of the earthquake.

• The time the earthquake occurred.

• The magnitude of the earthquake.

• The direction of the earthquake.

Why is it necessary to use multiple seismograph stations to locate an earthquake's epicenter?

• To confirm the magnitude of the earthquake.

• To determine the depth of the earthquake.

• To accurately pinpoint the epicenter by triangulation.

• To measure the speed of the waves.

What happens when circles from different seismograph stations intersect?

• They indicate the magnitude of the earthquake.

• They show the possible epicenter locations.

• They mark the end of the earthquake.

• They confirm the depth of the earthquake.

What is the minimum number of seismograph stations needed to accurately determine an earthquake's epicenter?

• Three

• Two

• One

• Four

What additional benefit is gained by using more than three seismograph stations?

• Better prediction of future earthquakes.

• Faster detection of the earthquake.

• Increased accuracy in locating the epicenter.

• Higher resolution of wave patterns.