Seismology is the scientific study of earthquakes and related phenomena, such as seismic waves, which are vibrations that travel through the Earth's interior. It is a branch of geophysics, which is the study of the physical properties of the Earth and its atmosphere. Seismologists use seismometers to measure the intensity, frequency, and duration of seismic waves, and use this data to gain insight into the structure of the Earth's interior and the processes that cause earthquakes.