Final answer:
Seismic waves from volcanic activity include pressure waves (P-waves) and shear waves (S-waves). These waves propagate through the earth with different speeds and characteristics, allowing geologists to study earthquake activity.
Step-by-step explanation:
Seismic waves from volcanic activity include two types of waves: pressure waves (P-waves) and shear waves (S-waves). P-waves are longitudinal waves that propagate through the earth by compressing and expanding the material they pass through.
S-waves are transverse waves that propagate by shaking the material perpendicular to the direction of wave travel. Both P-waves and S-waves have different speeds and characteristics, allowing geologists to study earthquake activity and determine the distance to the earthquake's epicenter.