Lesson 4 - Looking through Earth Inside

Plate tectonics theory

The theory that describes the movement and interaction of Earth's lithospheric plates.

Seismic waves

Waves of energy that are generated by earthquakes and travel through Earth's interior.

Mohorovičić discontinuity (Moho)

The boundary between the crust and the mantle, named after seismologist Andrija Mohorovičić.

Lithosphere

The rigid outer layer of Earth, consisting of the crust and upper mantle.

Asthenosphere

The partially molten region of the mantle beneath the lithosphere, responsible for the motion of tectonic plates.

Mesosphere

The lower part of the mantle, located beneath the asthenosphere.

Outer core

The liquid region of the core, composed mainly of iron and nickel alloy.

Inner core

The solid region at the center of Earth's core, composed of dense iron and nickel material.

Seismic discontinuity

A boundary within Earth's interior where there is a sudden change in seismic velocity.

Gutenberg discontinuity

The boundary between the mantle and the core, where P-waves slow down and hinder the movement of S-waves.

Lehmann discontinuity

The boundary between the inner and outer core, discovered by Inge Lehmann, indicating a solid region within the core.

Compositional Layers of the Earth

crust, mantle, core

Mechanical Layers of the Earth

lithosphere, asthenosphere, mesosphere, outer core, inner core

January 23, 1857

When was Andrija Mohorovičić born?

Volosko, Western Croatia

Where was Andrija Mohorovičić born?

1921

When did Andrija Mohorovičić retire?

1936

When did Andrija Mohorovičić die?

Crust

It is the layer made up of the oceanic and continental crust.

Mantle

It is made up of solid rock and lies between the core and the crust.

2900 km

How thick is the mantle?

4.01 × 10^(24)

What is the mass of the mantle?

67%

The mantle contributes to what percentage of the total mass of the Earth?

Peridotite

It as an ultramafic rock, which is made of iron and magnesium.

Conduction

It is when the heat coming from the core travels through the atoms by rapid collision with one another.

Convection

It is caused by heat currents that allow materials to flow and move freely.

Convection cells

As the materials move above the mantle, they cool down and start to sink back, replacing the hot materials that were heated by the core. This process of cooling and heating generates what?

Core

It is the inner part of the Earth. And it is the first one to be formed during the early years of the Earth.

Iron and nickel alloy

The core is made up of what?

31%

The core makes up what percentage of Earth’s composition?

Inner and outer core

The core is divided into two parts, which are?

4 000-5 000°C

What is the temperature of the outer core?

Average depth of the Moho

8 km under the ocean basin and around 32 km under the continental crust.

Andrija Mohorovičić

He discovered the Moho

Beno Gutenberg

He is a German-born American seismologist who found out that, at some depth, the P-wave slows down and hinders the movement of the S-wave. He also was the first to correctly determine the radius of the Earth’s core.

Inge Lehmann

She discovered the Lehmann discontinuity

1936

When did Inge Lehmann propose her theory that the Earth’s core is composed of two parts?