A Kid's Geology Primer: Build A Home Seismometer

"Geologists use photos, sound waves, drilling -- even earthquakes to find out what lies beneath your feet.

...Geologic maps can help you find your way across the landscape, but they have many other important uses, too. They help locate fossil fuels, such as natural gas and oil, as well as minerals and underground water supplies. They help builders locate safe, secure sites for new buildings and guide engineers planning the route of a new highway.

...You can make a seismometer to measure movements in your home..."

Thanks to Chris Steins