What are 3 factors that can change the speed or path of a seismic wave?

What are 3 factors that can change the speed or path of a seismic wave?

Seismic waves travel a curving path through the earth due to changes in composition, pressure, and temperature within the layers of the Earth.

Does gravity affect the speed of a seismic wave?

The Tohoku quake provided an ideal opportunity to study the effects of the quake on Earth’s gravity, Montagner says. Gravity signals travel very near the speed of light, so the signals can be detected before seismic waves, which travel at closer to the speed of sound at Earth’s surface.

Which factor does not effect the speed of a seismic wave?

Materials with zero rigidity – i.e., fluids – do not carry shear waves at all. Therefore, the absence or presence of groundwater has no effect on the shear wave velocity. It is interesting to note that, in general, seismic velocity increases with density – denser rocks tend to be much harder and faster.

Why do seismic waves change speed as they travel through Earth?

The waves are refracted as they travel through the Earth due to a change in density of the medium. This causes the waves to travel in curved paths. When the waves cross the boundary between two different layers, there is a sudden change in direction due to refraction.

Which seismic waves travel faster?

P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves, rock oscillates perpendicular to the direction of wave propagation. In rock, S waves generally travel about 60\% the speed of P waves, and the S wave always arrives after the P wave.

What type of seismic waves has the fastest velocity?

P-waves. P-waves, also known as primary waves or pressure waves, travel at the greatest velocity through the Earth. When they travel through air, they take the form of sound waves – they travel at the speed of sound (330 ms-1) through air but may travel at 5000 ms-1 in granite.

Are seismic waves affected by water at the surface?

Seismic waves are blind to water.

What factors affect seismic velocity?

Composition, temperature, and pressure are all factors that can affect seismic velocity in the mantle. Laboratory elasticity data show that a decrease of 1\% in the Mg/(Mg+Fe) ratio in olivine reduces the velocity by an amount equivalent to that caused by a temperature increase of 70 K.

When seismic waves slow down what does it indicate?

Seismic waves move more slowly through a liquid than a solid. Molten areas within the Earth slow down P waves and stop S waves because their shearing motion cannot be transmitted through a liquid. Partially molten areas may slow down the P waves and attenuate or weaken S waves.

Why do seismic waves travel faster in cratonic roots?

Cratons are known to be colder and less dense than the surrounding mantle, which would in turn yield slightly faster sound waves, but not quite as fast as what has been measured.

What happens when seismic waves reach the core of the Earth?

Figure 19.2a: P-waves generally bend outward as they travel through the mantle due to the increased density of mantle rocks with depth. When P-waves strike the outer core, however, they bend downward when traveling through the outer core and bend again when they leave. The bending of seismic waves is called refraction.

Why seismic waves travel slowly?