A seismologist is someone who looks into earthquakes. Seismologists study earthquakes by using seismographs and going out into the field to look at the damage caused by an earthquake.
Seismographs are tools that record how seismic waves make the surface of the Earth move. The first seismograph was made by Chang Heng in the year A.D. 132, and they called it an earthquake weathercock. There were eight dragons on this instrument, and each one had a bronze ball in its mouth. When an earthquake happened, the seismograph had a mechanism that opened one of the dragons’ mouths. When the ball fell into the mouth of one of the toads, it was a sign that an earthquake was coming.