Seismic waves are vibrations or energy waves that travel through the Earth during an earthquake or other ground-shaking events.These waves are caused by sudden movements in the Earth’s crust, like faults breaking or volcanic eruptions. They move in different directions and speeds, depending on the type of wave and the material they pass through.There are two main types:Body waves – travel through the inside of the Earth (includes P-waves and S-waves).Surface waves – move along the Earth's surface and usually cause the most damage during earthquakes.In short, seismic waves are the reason why we feel the ground shaking during an earthquake.