seismometers

/saɪzˈmɑmətərz/
noun
  1. Instruments that measure and record the movements of the ground, especially during earthquakes.
    • The data from the seismometers showed that the earthquake had a magnitude of 6.2.
    • Scientists placed seismometers around the volcano to detect any small tremors.
    • Modern seismometers are so sensitive they can pick up vibrations from a truck driving nearby.