An earthquake occurs when underground rocks suddenly break along a fault due to the buildup of stress and strain from tectonic plate movements. This sudden break releases stored elastic strain energy as seismic waves, causing the ground to shake. The initial rupture point underground is called the focus or hypocenter, and the surface location above it is called the epicenter. Earthquakes often happen where tectonic plates collide, slide past, or pull away from each other, causing the rocks to deform until they abruptly slip and release energy.
Process of Earthquake Occurrence
- The Earth's crust is made up of tectonic plates that are constantly moving.
- Due to friction, these plates can get locked at their edges while stress accumulates.
- When the stress exceeds the frictional resistance, the rock breaks suddenly along a fault.
- This sudden slip releases energy in the form of seismic waves that travel through the Earth, producing the shaking felt during an earthquake.
Key Terms
- Focus (Hypocenter): The underground point where the rock first breaks.
- Epicenter: The point on the Earth's surface directly above the focus.
- Fault: A fracture in the Earth's crust where movement occurs.
This release of energy and movement along faults is the fundamental cause of earthquakes.
