# EI 2-2 Earthquakes and Seismic Waves

## 14 terms

### How does the energy of an earthquake travel through Earth?

Seismic waves carry energy from an earthquake away from the focus, through Earth's interior, and across the surface.

### What are the scales used to measure the strength of an earthquake?

Three commonly used methods of measuring earthquakes are the Mercalli scale, the Richter scale, and the moment magnitude scale.

### How do scientists locate the epicenter of an earthquake?

Geologists use seismic waves to locate an earthquake's epicenter.

### Earthquake

The shaking and trembling that results from the movement of rock beneath Earth's surface.

### Focus

The area beneath Earth's surface where rock thta is under stress breaks, triggering an earthquake.

### Epicenter

The point on the surface directly above the focus.

### P wave

Seismic waves that compress and expand the ground like an accordion.

### S wave

Seismic waves that vibrate from side to side as well as up and down.

### Surface wave

Waves that move more slowly that P waves and S waves, but they can produce severe ground movements.

### Mercalli scale

A scale that was developed to rate earthquakes according to the level of damage at a given place.

### Magnitude

A number that geologists assign to an earthquake based on the earthquake's size.

### Richter scale

A rating of an earthquake magnitude based on the size of the earthquake's seismic waves.

### Seismograph

An instrument that records and measures seismic waves.

### Moment magnitude scale

A rating system that estimates the total energy released by an earthquake.