GEOLOGY

Detailed explanation-1: -The speed at which seismic waves travel depends on the properties of the material that they are passing through. For example, the denser a material is, the faster a seismic wave travels (SF Table 7.1). P waves can travel through liquid and solids and gases, while S waves only travel through solids.

Detailed explanation-2: -Seismic waves travel faster in denser rocks; temperature tends to lower the speed of seismic waves; and pressure tends to increases the speed.

Detailed explanation-3: -Its existence can be explained by the way seismic waves bend as they travel through the Earth and by the inability of S-waves to travel through liquids. When seismic waves travel through material that changes density gradually, they change direction gradually.

Detailed explanation-4: -Seismic waves travel at different speeds through different materials. In this 2-layer model two wave fronts leave an impact at the same time but the lower layer is faster. Seismic waves travel a curving path through the earth due to changes in composition, pressure, and temperature within the layers of the Earth.

Detailed explanation-5: -When a wave encounters a change in material properties (seismic velocities and or density) its energy is split into reflected and refracted waves. The amplitude of the reflection depends strongly on the angle that the incidence wave makes with the boundary and the contrast in material properties across the boundary.