How does the structure of earths interior affect seismic waves?
As the Earth’s outer core is liquid, and inner core is very dense, this affects the waves as they travel through the Earth. It speeds them up and slows them down according to the density. Because S can’t go through the outer core, there is a “shadow zone” at a certain area on the Earth where there are no S waves at all. P waves also have a smaller shadow zone, where the waves are diflected and bent within the outer core.