Discontinuities

Question 1

The 3 mains seismic discontinuities

Answer 1

1) Moho discontinuity - The border between the continental crust and the Mantle. Between 30 and 70 km (continental) and 7 to 8 km (oceanic)
2) Wiechert-Gutenberg Discontinuity - The border between the external core and mantle (2,900 km)
3) Core Discontinuity - The border between the inner and outer core (5,155 km).

Continental Crust
---------------------------  Moho
Mantle 
--------------------------- Wiechert-Gutenberg
External Core
--------------------------- Core dis.
Inner Core

Question 2

What are the smaller seismic discontinuities in the crust?

Answer 2

400 km - Olivine becomes Olivine beta

650 km - Olivine gamma becomes ferro-periclase or Magnesium silicate perovskite

Question 3

What are the smaller seismic discontinuities in the mantle?

Answer 3

Upper Mantle - between the Moho and 400 km

Transition Zone - (400 - 1000 km)

Lower Mantle (1000 - 2900 km)

Question 4

How deep is the “D” layer?

Answer 4

200-400 km

Question 5

What is the conrad discontinuity?

Answer 5

It is a seismic discontinuity that divided the continental crust into an upper and lower portion.

Question 6

What are the layers of the earth (spheres) - Which are defined by the mechanic properties

Answer 6

1) Lithosphere (50-100km) oceanic (40-200km) continental - it is defined as a rigid exterior - the crust and part of the mantle
2) Asthenosphere from (80-20km) to (700 km) - It essentially has the upper mantle - it is viscous and mechanically weak
3) Mesosphere - Starts at a sharp seismic jump at 660 km to 2,700 km - The lower mantle to the external core - Rigid area