ELI5: Explain Like I'm 5

Seismometer

A seismometer is a special machine that measures earthquakes. It works by detecting vibrations in the ground caused by the movement of the Earth's plates. The machine then measures the strength, or magnitude, of the vibrations and records the information. Seismometers help scientists learn more about earthquakes and can also be used to warn people when earthquakes are occurring so they can take the necessary safety measures.