Earthquakes Pages 246-254 Vocabulary 1. crust - the Earth’s thinnest, outermost layer 2. plates - gigantic, moving slabs of rock that forms Earth’s crust 3. fault - a break or crack in Earth’s crust where two plates come together 4. earthquake – movements in Earth’s crust caused by a sudden shift of Earth’s plates along faults 5. creep – slow movement along faults 6. tsunami – a giant ocean wave caused by earthquakes on the ocean floor Facts to Know: The Earth is made up of layers. Breaks or cracks in Earth’s crust where plates come together are called faults. Plates fit together like pieces of a puzzle, and are always moving. Movement along faults can be a slow creep or a sudden shift. When plates shift suddenly, an earthquake may occur. Mountains and volcanoes can also form as plates move. Most earthquakes happen at faults, where Earth’s plates meet. There are three types of faults: normal fault, reverse fault, and strike-slip fault. The vibrations of an earthquake are the strongest where the earthquake first begins below the ground. The vibrations of an earthquake travel away from the center. Tsunamis are usually caused by earthquakes on the ocean floor. When a tsunami hits, move to higher ground. Normal Fault Reverse Fault Strike-Slip Fault