Earthquakes are usually triggered when rock located beneath the ground, on top of fault lines, breaks and suddenly releases a significant amount of energy. The immediate and rapid release of energy caused by earthquakes generates seismic waves, which cause shaking motions that start below the Earth’s surface and spread across large distances.
The substances that form earthquakes are generally large blocks of rocks that break up due to internal pressure that builds over time. Earthquakes are caused by two tectonic plates that push against each other. The internal pressure between the plates increases, which creates friction and heat, and ultimately creates energy. Earthquakes are triggered after rocks break apart, or when the two tectonic plates stick together instead of sliding. The seismic waves and energy created by earthquakes causes plates or rocks to begin moving. Once they are activated by earthquakes, rocks and plates continue to move freely until they become stuck together, which limits their mobility. The exact location where rocks break and disseminate waves that trigger earthquakes is called the focus. Just above the focus is the earthquake epicenter, which is located above the surface of the Earth. Earthquakes occur around the world and vary in intensity and frequency, but nevertheless are all formed in the same manner.