Detecting earthquakes main content.

Detecting earthquakes

Part of Hall of Planet Earth.


Geologists peer into the Earth using a seismometer, an instrument that senses ground movements from earthquakes. A weight is attached to a pendulum or stiff spring, and when the seismic waves cause ground motion, the weight remains stationary while the rest of the instrument moves with the ground. A rotating drum, or seismograph, graphically records the movement over time.