Monitoring Earthquakes

Front

What is the epicenter of an earthquake?

Back

The point on the Earth's surface directly above where an earthquake originates.

Front

What is the focus of an earthquake?

Back

The actual location inside the Earth where the earthquake starts.

Front

What are P waves?

Back

Primary waves that are the first to arrive during an earthquake; they compress and expand the ground.

Front

What are S waves?

Back

Secondary waves that arrive after P waves; they move the ground up and down or side to side.

Front

How do seismographs work?

Back

Seismographs record the vibrations caused by seismic waves during an earthquake.

Front

What does it mean if a city is far from the epicenter?

Back

It means that the city will experience weaker shaking and a longer time delay between P and S waves.

Front

What is a seismogram?

Back

A visual record produced by a seismograph that shows the intensity and duration of seismic waves.

Front

Why do scientists analyze multiple seismograms?

Back

To triangulate the location of the earthquake's epicenter by comparing the arrival times of seismic waves.

Front

What is the relationship between distance from the epicenter and wave arrival time?

Back

The farther a seismic station is from the epicenter, the longer it takes for the seismic waves to arrive.

Front

What is the Richter scale?

Back

A scale used to measure the magnitude of an earthquake based on the amplitude of seismic waves.