Earthquakes are caused by movements within the Earth's crust or mantle. They originate at focal points and send shock waves to the epicenter, or point above the focal point on the surface. There are three types of waves produced - P waves, S waves, and surface waves. P waves are compressional waves that can travel through solids and liquids. S waves are shear waves that move sideways and can only travel through solids. Surface waves cause the most damage to buildings by making the ground rise and fall in circular motions. Together, these wave types are responsible for significant loss of life and property damage from earthquakes each year.