SOLAR SYSTEM

Detailed explanation-1: -The ‘Moho Discontinuity’ is the boundary between the crust and mantle. It has been named so as it was discovered by Croatian Seismologist Andrija Mohorovicic. This boundary marks a change in the seismic waves velocity from the crust to the uppermost mantle within the lithospheric plate.

Detailed explanation-2: -Figure 3.7 Patterns of seismic wave travel through Earth’s mantle and core. S-waves can’t travel through the liquid outer core, so they leave a shadow on Earth’s far side. P-waves do travel through the core, but P-wave refraction bends seismic waves away from P-wave shadow zones.

Detailed explanation-3: -Mantle rock is generally denser and stronger than crustal rock and both P-and S-waves travel faster through the mantle than they do through the crust. Moreover, seismic-wave velocities are related to how tightly compressed a rock is, and the level of compression increases dramatically with depth.

Detailed explanation-4: -This sudden velocity change shows us that at the Moho, there is a significant change in the density of the material. The layer beneath the crust (the mantle) is more dense than the crust, and so the P-waves speed up when they enter it. Moho: What is It?

Detailed explanation-5: -Seismic waves tell us that the Earth’s interior consists of a series of concentric shells, with a thin outer crust, a mantle, a liquid outer core, and a solid inner core. P waves, meaning primary waves, travel fastest and thus arrive first at seismic stations. The S, or secondary, waves arrive after the P waves.

Detailed explanation-6: -The crust under the oceans is much thinner (3-8 km). Seismic waves travel faster in oceanic crust than in continental crust. Because of this velocity difference, it is assumed that the two types of crust are made up different kinds of rock. Seismic P waves travel through oceanic crust at about 7 kilometers per second.