Complex sentence: P-waves are a type of elastic wave, called seismic waves in seismology, that can travel through a continuum gases (as sound waves), solids and liquids, including the Earth.
Split into simpler sentences: P-waves are a type of elastic wave, called seismic waves in seismology, that can travel through a continuum. If the continuum is made up of gases (as sound waves), solids and liquids, including the Earth.