INTRODUCTION
California is famous for towering mountains, awesome deserts, and hundreds of miles of scenic coastline. But one part of its geography doesn't appeal to tourists or please residents. California is earthquake country!

What is an earthquake like? During a small earthquake, people often feel the ground gently shake and see objects around them sway or wobble. A larger earthquake may feel rough and bumpy like riding a bike along a rocky path. Sometimes the movement is a sharp jolt, like someone surprising you with a hard push.

Earthquakes are caused by rocks breaking in the Earth's outer layer. The rupture makes the ground shake. The closer you are to where the earthquake began, the stronger the shaking.

Usually we feel an earthquake for a few seconds, but strong quakes can move the earth for up to three minutes. Sometimes the shaking in the ground causes a sound in the air, and we can "hear" the earthquake.