A Seismograph
Seismagraph
A seismograph.
Seismometer
seismogram
The term magnitude is used to describe the size of an earthquake.
Richtor scales
I think it's a seismograph.
A heart-rate monitor is used.
A seismometer, or seismograph. One of the two! :)
A seismograph is an instrument used to measure movement of earthquake. It measures the seismic waves of that area.
You use a seismograph to measure the strength of an earthquake.