Scientists use devices called seismographs to measure the ground's motion.
When the Earth moves as a result of an earthquake seismographs all around the world pick
up the signal as the seismic waves pass by.
Modern seismographs use electronic voltage to record ground motion on a computer. They are used to monitor ground motion on land and on the ocean floor. These devices are sensitive enough to record motion from blowing trees, cars and trucks on the highway, or ocean waves crashing on the beach! |
Inspecting a seismograph installed in its vault. |
Seismograph being lowered to ocean floor.
A few older seismographs still use paper to record activity.
