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Studying Earth’s Interior. Chapter 10 Section 4. Studying the Earth’s Interior. Studying earthquakes has provided knowledge of the Earth’s interior. Changes in velocity of S and P waves as they move through Earth indicate the depth and density of the layers it passes through. The Shadow Zone.
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Studying Earth’s Interior Chapter 10 Section 4
Studying the Earth’s Interior • Studying earthquakes has provided knowledge of the Earth’s interior. • Changes in velocity of S and P waves as they move through Earth indicate the depth and density of the layers it passes through.
The Shadow Zone • Earthquake waves travel in all directions from the focus. • Not all earthquake stations do not detect an earthquake. • Those in the earthquake’s shadow zone may not record the earthquake.
The Shadow Zone Cont. • The shadow zone is a belt around the Earth opposite to the focus. • Stations in the shadow zone do not detect P waves because they are refracted as the move through the core. • S waves are blocked because they cannot go through the core.
The Moho • The Mohorovičić discontinuity is the boundary between the crust and the mantle. • This was discovered in 1909 by Andrija Mohorovičić, a Croatian seismologist. • Moho is a shorter name for this feature.
The Transition Zone • S and P wave velocities have been found to change at a certain depth in the mantle. • The location of this change is called the transition zone. • The reason for this change is the difference of density between the upper and lower mantle.
The Transition Zone Cont. • The reason for the differences in density is the greater pressure in the lower depth which make it denser which slows the velocity of waves.