Earthquake

Focus: area beneath Earth's surface where earthquake is triggered.

Epicenter: point on the surface of the earth directly above the focus.

Seismic waves

• Vibrationsthat travel through earth
• Carry energy released during earthquake
• Away from focus, through interior, across the surface

Types of seismic waves

• P waves: primary, vibrates crust forward and back
• S waves: secondary, vibrates crust up/down, side/side
• Surface waves: slower, ground rolls

Seismograph