Scientist classify waves by moving through a medium and/or empty space. For example, a wall, air, water, space.
The speed of the waves that travel through the interior can tell the density of each layer of the Earth. Some waves can make it through certain layers, but not others.
Seismic waves can be separated into basically two different types; S-waves and P-waves. P-waves are able to travel through liquid and solid, but S-waves can not travel through a liquid, they can only travel through a solid. When scientist "shoot" P and S-waves at the outer core, they detect the P-waves coming out the other side, but not the S-waves.
Because they don't need any material substance to travel through in order to get from place to place.
A+ answer: all waves change directions as they travel through different materials
They don't. The Earth's crust is composed mostly of silicate minerals. The core is believed to be metal based on the behavior of seismic waves passing through it. The density of the core is consistent with iron and nickel.
Waves may be classified according to the direction of vibration relative to that of the energy transfer
A seismologist. Names, I'm not so good at.
An Oceanographer!
Scientist Henry Colony
They measure how waves from earthquakes travel through the earth, and they test how waves travel through liquid and solid and goo, and they compare the results to find the consistency of the inner core and other layers of the earth.
The wave are classified as their motion respect to their propagation.
Scientists shot semantic waves through the layers to find out how much velocity each layer has.