What are seismometers and seismographs?

A seismometer is the internal part of the seismograph, which may be a pendulum or a mass mounted on a spring; however, it is often used synonymously with "seismograph". read more

Seismometers are instruments that measure motion of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources such as by the use of explosives.[1] Records of seismic waves allow seismologists to map the interior of the Earth, and locate and measure the size of these different sources. read more

A seismograph, or seismometer, is an instrument used to detect and record seismic waves. Seismic waves are propagating vibrations that carry energy from the source of an earthquake outward in all directions. They travel through the interior of the Earth and can be measured with sensitive detectors called seismographs. read more