Natural disasters like earthquakes occur due to the movement of tectonic plates beneath the Earth's surface. The Earth's outer shell is divided into several large plates that float on the semi-fluid layer of the mantle. When these plates move against each other, they can collide, slide past each other, or move apart. The friction between these plates builds up over time until it is released in the form of seismic energy, causing the ground to shake violently, resulting in an earthquake.