What are gravimeters?

A gravimeter is like a super-sensitive scale that can feel tiny changes in gravity, just like when you step on a bathroom scale and it shows how heavy you are.

Imagine you're playing with a seesaw at the park. If you sit on one end, it goes down, and your friend sits on the other end, it goes up. Now imagine you have a really, really tiny seesaw, so small that even a single grain of sand can make it move. That's kind of what a gravimeter does. It measures how gravity pulls things toward Earth, and if something changes, like more rock is under the ground or less, the scale moves just a little bit.

A gravimeter uses special sensors that are very sensitive. These sensors can notice even the tiniest differences in how strong gravity is at different places on Earth.

Think of it like a super-smart bug that lives inside the ground and tells you when things shift, like when a mountain moves or an underground cave opens up!