seismometer

noun

1. A device used by seismologists to detect and measure seismic waves and therefore locate earthquakes etc; a seismograph.

   “Despite the Hebgen Lake quake and the other known risks, Yellowstone didn't get permanent seismometers until the 1970s.”

   “Researchers monitor the volcano through instruments and cables that extend from the coast. Among them are seismometers, which provide real-time data on the earthquakes occurring near the volcano, Chadwick said.”