Final answer:
A seismometer is an instrument used to record the ground motions produced by an earthquake, including seismic waves like P-waves and S-waves, which are critical for determining the epicenter of earthquakes and monitoring compliance with nuclear test bans.
Step-by-step explanation:
A seismometer is a scientific instrument used to record ground motions produced by an earthquake. Seismometers are essential tools in geophysics, and they work by using geophones to convert ground movement into voltage, which can then be analyzed to study the structure of the Earth. The motions recorded are known as seismic waves, which include different types such as pressure waves (P-waves) and shear waves (S-waves).
These waves help determine the distance to an earthquake's epicenter by comparing the arrival times of the S- and P-waves, which travel at different speeds through various materials. The precision of such measurements can reveal the distance to the source of the earthquake and are also useful in monitoring nuclear bomb tests as part of international test ban treaty enforcement.