The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves .
What is the shadow zone of P-wave?
The shadow zone of P-waves appears as a band around the earth between 103° and 142° away from the epicentre . This is because P-waves are refracted when they pass through the transition between the semisolid mantle and the liquid outer core.
Why P-wave has shadow zone?
P waves do travel through liquids, so they can make it through the liquid part of the core. Because of the refraction that takes place at the CMB, waves that travel through the core are bent away from the surface , and this creates a P wave shadow zone on either side, from 103° to 150°.
What is true of the P-wave shadow zone shown here?
What is true of the P-wave shadow zone, shown here? An iceberg will sink into the sea until it displaces its own weight in water, leaving only the “tip of the iceberg” exposed when it floats .
Why are there no P waves or S waves received in the P waves shadow zone?
You will notice above that all seismic waves travel along curved paths. One result is that there is a zone on the Earth that will not receive any P-Waves due to the bending of the waves as they travel through the different layers of the Earth . This is known as the P-Wave Shadow Zone.
Where do P waves travel the fastest?
Because the earth’s mantle becomes more rigid and compressible as the depth below the asthenosphere increases, P-waves travel faster as they go deeper in the mantle. The density of the mantle also increases with depth below the asthenosphere. The higher density reduces the speed of seismic waves.
Why do P waves come first?
The direct P wave arrives first because its path is through the higher speed, dense rocks deeper in the earth . The PP (one bounce) and PPP (two bounces) waves travel more slowly than the direct P because they pass through shallower, lower velocity rocks. The different S waves arrive after the P waves.
What does the P stand for in P wave?
Compressional waves are also called P-Waves, (P stands for “primary” ) because they are always the first to arrive.
Where do P waves originate?
The P wave represents the electrical depolarization of the atria. In a healthy person, this originates at the sinoatrial node (SA node) and disperses into both left and right atria.
What is difference between P and S waves?
P waves are recorded earlier than S waves , because they travel at a higher velocity. ... P waves can travel through liquid and solids and gases, while S waves only travel through solids. Scientists use this information to help them determine the structure of Earth.
Why do seismic waves change direction?
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 .
Why are P waves received but S waves are not?
Answer: P and S waves are types of seismic waves . The reason whey P waves are received but S-waves are not received by seismic stations located on the opposite side of Earth from an earthquake epicenter is because those waves (S-waves) cannot travel through the liquid core of the earth .
Why do earthquakes develop shadow zone 11?
(iii) Earthquake waves develop shadow zones because of the properties of each (P and S) waves as well as the core . Outer crust is liquid and hence S-waves, which can travel only through solid material, is blocked and cannot move across the core.
What does the P wave shadow tell us about Earth’s composition?
Seismic waves from an earthquake’s focus travel through the earth along bent paths and are eventually recorded by distant seismograph stations. ... This indicates that P-waves slow down in the outer core, suggesting that this layer has a significantly different composition from the mantle and may actually be liquid .
What is it called when a seismic wave bounces backward?
refraction. What is it called when a seismic wave bounces backward when it reaches a boundary? reflection .
What is the P wave shadow zone and what causes it quizlet?
Why is there a P-wave shadow zone? The P-wave shadow zone is the result of the refraction effects P-waves go through as they travel deep inside the Earth . It extends from 105 to 142 degrees.
