Earthquakes occur when stress builds up in Earth's crust along fault lines, causing rocks to fracture and slip past each other. There are three main types of faults - strike-slip, normal, and reverse - which form due to different types of stress. When fault slippage occurs, it releases seismic waves that radiate outward. Seismographs can detect these waves and use their properties to determine the earthquake's location, magnitude, and type of fault movement. Major earthquakes pose a threat through ground shaking and secondary effects like fires, landslides, and tsunamis that can damage infrastructure and endanger human lives.

1. Earthquakes