järistykseen

Järistys, also known as an earthquake, is the sudden shaking of the ground caused by the movement of tectonic plates beneath the Earth's surface. These plates are massive, irregularly shaped slabs of solid rock that make up the Earth's lithosphere. They are constantly in motion, albeit very slowly, due to convection currents in the Earth's mantle.

When these plates interact, they can collide, pull apart, or slide past each other. These movements build up stress within the rocks along the plate boundaries, which are called fault lines. When the accumulated stress exceeds the strength of the rocks, they rupture, releasing energy in the form of seismic waves. These waves travel through the Earth and cause the ground to shake.

The intensity of an earthquake is measured using seismographs, which record the ground motion. The magnitude of an earthquake is typically expressed on the Richter scale or the moment magnitude scale, with larger numbers indicating more powerful shaking. The effects of an earthquake can range from barely perceptible tremors to widespread destruction, depending on its magnitude, depth, and the local geological conditions. Earthquakes can trigger secondary hazards such as tsunamis, landslides, and liquefaction.