EARTHQUAKES
Forces inside the earth’s mantle and near its surface push, stress, and deform rocks. At some point the stress can cause the rocks to suddenly shift or break and produce a transform fault, or fracture in the earth’s crust. When a fault forms, or when there is abrupt movement on an existing fault, energy that has accumulated over time is released in the form of vibrations, called seismic waves , which move in all directions through the surrounding rock. This internal geological process is called an earthquake . Most earthquakes occur at the boundaries of tectonic plates , when colliding plates create tremendous pressures in the earth’s crust or when plates slide past one another at transform faults. The place where an earthquake begins, often far below the earth’s surface is called the focus . The earthquake’s epicenter is located on the earth’s surface directly above the focus. The energy of the earth’s tremendous internal stress is released in the form of seismic (shock) waves, wh