Earthquake
In short
An earthquake is a sudden shaking of the ground caused by movement deep inside the Earth's crust. This movement usually happens when rocks break or slip along fault lines.
In plain words
The Earth's outer shell is made of large pieces called tectonic plates. These plates are always moving very slowly. Sometimes, they get stuck against each other while trying to slide past. When the pressure builds up too much, the rocks snap and release a huge burst of energy. This energy travels through the ground as waves, which makes everything shake.
A simple example
Imagine you are trying to slide two pieces of rough sandpaper against each other. At first, they catch and stick. You push harder and harder until they suddenly slip with a loud jerk. That sudden slip is like an earthquake.
Why it matters
Earthquakes are important to study because they can be very dangerous. They can cause buildings to fall down, trigger landslides, or create large waves in the ocean called tsunamis. Knowing where earthquakes happen helps engineers build stronger houses and helps cities prepare for emergencies.
Easy to mix up
People often mix up an earthquake with a volcanic eruption. While both involve the Earth moving, an earthquake is caused by shifting rocks and pressure, whereas a volcanic eruption is caused by molten rock and gas rising to the surface.