Final answer:
The arrival times and amplitude of P-waves and S-waves as measured by seismographs help determine the distance to the earthquake's epicenter and its magnitude.
Step-by-step explanation:
The two different types of seismograph lines, or seismic waves, that indicate the size of an earthquake are P-waves (pressure waves) and S-waves (shear waves).
The P-waves arrive first and have higher speeds than S-waves because they can travel through both liquids and solids, while S-waves only move through solids and are slower.
The size of an earthquake is often measured using a semi-log plot like the Richter scale, which correlates the amplitude and energy of seismic waves to the earthquake's magnitude on a logarithmic scale.
A large difference in arrival times between P-waves and S-waves at a seismograph station indicates a more distant epicenter, while a shorter time difference indicates a closer epicenter. The amplitude of these waves, measured by the seismograph, is used to calculate the magnitude of the earthquake.