Why is there a boundary between the solid mantle and molten mantle?
The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of the core.
Where is the core mantle boundary located?
The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2891 km (1796 mi) depth beneath the Earth's surface.
How can we prove the existence of the crust-mantle boundary?
This was done for the crust mantle boundary, which is called the Mohorovičić discontinuity, which was found by seismologists Andrija Mohorovičić. You obviously do not understand science. We can not prove the existence of the boundary between crust and the mantle.
What is the core-mantle boundary?
Core–mantle boundary. Schematic view of the interior of Earth. The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron - nickel outer core. This boundary is located at approximately 2891 km (1796 miles) depth beneath Earth's surface. The boundary is observed via the discontinuity in seismic wave ...
What proves the existence of the boundary between the crust and mantle?
The Moho is the boundary between the crust and the mantle in the earth. This is a depth where seismic waves change velocity and there is also a change in chemical composition. Also termed the Mohorovicic' discontinuity after the Croatian seismologist Andrija Mohorovicic' (1857-1936) who discovered it.
What is the boundary between the mantle and the core?
INTRODUCTION. The largest compositional discontinuity within the Earth is the core-mantle boundary (CMB), at a depth of 2889 km. This boundary and the adjacent transition zones in the lowermost mantle and outermost core play a critical role in the Earth's thermal and chemical evolution.
What proves the existence of the boundary between?
What proves the existence of the boundary between the crust and the mantle? Seismic wave diffraction shows a boundary between more and less dense rocks that is commonly taken to be the crust-mantle boundary. It's called the Mohorovicic discontinuity or Moho for short.
Why is the core-mantle boundary important?
The CMB region is relevant to core evolution for two reasons. First, it is the behavior of this region, and in particular its temperature structure, which controls the rate at which heat is extracted from the core. As a consequence, the thermal evolution of the core is intimately tied to that of the mantle.
Which layer separates the core from the mantle?
Mohorovicic Discontinuity (Moho): separates the crust from the mantle. Asthenosphere: highly viscous, mechanically weak and ductile part of mantle. Gutenberg Discontinuity: lies between the mantle and the outer core.
What separates crust from mantle?
Mohorovicic Discontinuity (Moho) separates the mantle from the crust. Asthenosphere is the highly viscous part of the mantle, mechanically weak and ductile.
Why is the Moho of importance?
1 Answer. The Mohorovicic discontinuity is important because it marks the boundary between the mantle of liquid magma and the hardened magma that forms the curst.
Where is Gutenberg discontinuity found?
The mantle–core boundary is the Gutenberg discontinuity at a depth of about 2,800 kilometres. The outer core is thought to be liquid because shear waves do not pass through it.
What are the two boundaries in mantle?
The so-called “410-kilometer discontinuity” marks the boundary of the transition zone. The Gutenberg discontinuity is more popularly known as the core-mantle boundary (CMB).
What are the boundaries between the layers of the earth?
The boundary between the crust (continental or oceanic) and the underlying mantle is known as the Mohorovičić discontinuity (also called Moho), which is named for its discoverer, Croatian seismologist Andrija Mohorovičić.
What is the boundary between the mantle and core?
The boundary between the mantle and core or the mantle core interface is known as the Gutenberg Discontinuity. Here there is an abrupt change in the seismic waves. Primary seismic waves decrease in velocity while secondary seismic waves disappear completely. It is dense probably due to a greater percentage of iron.
What is the core mantle boundary?
Core–mantle boundary (CMB) is one of the most inaccessible and enigmatic regions on the Earth. Clearly distinct chemical nature of the mantle (dominated by silicates and oxides) and the outer core (liquid iron–nickel alloy) suggests a possibility of multiple and complex chemical reactions at CMB. The ~200 km thick layer of the lower mantle directly above the boundary is referred to as the D″ region and it is considered as a narrow transition zone of multiphase behavior .In the transition zone the gradient of density is much greater than outside it, i.e., in the mantle and core. High-pressure e
What is the CMB boundary?
The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. Thisboundary is located at approximately 2891 km (1796 mi) depth beneath the Earth's surface.
How thick is the Mohorovicic discontinuity?
The Mohorovicic Discontinuity makes up the boundary between the Crust and the Mantle. It is about 500m thick.
How is the Earth's interior structure based on seismic?
Our modern, scientific understanding of the Earth's interior structure is based on inferences made with the help of seismic monitoring. In essence, this involves measuring sound waves generated by earthquakes, and examining how passing through the different layers of the Earth causes them to slow down. The changes in seismic velocity cause refraction which is calculated (in accordance with Snell's Law) to determine differences in density.
How big is the Earth's crust?
The diameter of the Earth is around 7900 miles. The Crust is roughly only around 20 miles thick. In some areas its a lot thinner with pockets being harder minerala like nixkel, iron and various areas molten lava that find its way all the way to the surface (e.g. Hawaii's Main Island, Pacific Ring of Fire, etc...) Although there are scientific determinations that give us ideas and knowing that these measurements fluctuate in different parts of the planet, nothing is EXACT unless we actually GO THERE. Like everything in science, it's "theoretical" until Proven to be FACT.
Why did he claim that the inner sphere was held in place by the force of gravity?
Between this and an inner sphere, he reasoned there was an air gap of the same distance. To avoid collision, he claimed that the inner sphere was held in place by the force of gravity. The model included two inner concentric shells around an innermost core, corresponding to the diameters of the planets Mercury, Venus, and Mars respectively.
Answer
Seismic wave diffraction shows a boundary between more and less dense rocks that is commonly taken to be the crust-mantle boundary. It's called the Mohorovicic discontinuity or Moho for short. It's usually at 30-40 km depth underneath continents, but can be as deep as 80 km.
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