Internal dynamics of the Earth

Internal dynamics of the Earth Internal dynamics of the Earth

The study of phenomena caused by the internal energy of the planet:

• Movement of continents• Origin of dorsal ridges and ranges• Volcanic eruptions• Earthquakes• Formation of some rocks

Characteristics of the interior of the Earth

At a depth of 50 km:• the temperature is 600 ºC• the pressure is 20,000 atmospheres

Temperature and pressure increase with depth.

Rate of increase in temperature:

30 ºC per kilometre

GEOTHERMALGRADIENT

Structure of the Earth

The Earth is believed to have a solid inner core, made mostly of iron and nickel. This is surrounded by a liquid outer core, also mostly iron and nickel.

The upper part of the mantle and the crust together are called the lithosphere. Sitting just below the lithosphere is a region of plastic consistency called the aesthenosphere.

At divergent boundaries, plates move apart.

At convergent boundaries, plates push together.

At transform boundaries, plates slide by each other.

Plates move in three ways.

Plate tectonics

(Constructive) (Destructive) (Conservative)

seismic waves

epicentre

hypocentre (focus)

Earthquakes are caused by a sudden release of energy fromthe Earth’s crust.

Earthquakes

An earthquake is the shaking of the Earth's surface due to a sudden release of energy from the crust.

Earthquakes usually happen along convergent (destructive) and transform (conservative) plate boundaries.

Plates do not always move smoothly alongside each other and sometimes get stuck. When this happens, pressure builds up. When this pressure is released, an earthquake can occur.

Earthquake energy is released in seismic waves that spread out from the focus. The waves are felt most strongly at the epicentre, where the most severe damage caused by an earthquake will happen.

seismogram

seismographStudying seismic waves

seismic waves

WHAT OTHER INFORMATIONCAN SCIENTISTS LEARN FROM SEISMIC WAVES?

Seismic waves

Answer: They can learn informationabout the internal structureof the Earth.

crater

volcanic cone

PYROCLASTICMATERIALS

GASES

LAVA

magma chamber

chimney

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Eruptions and volcanic material

PYROCLASTIC MATERIAL

ash

lapilli

volcanicbombs

Eruptions and volcanic material

(SOLID)

(< 2 mm Ø)

(2-64 mm Ø)

(> 64 mm Ø)

GASES

carbon dioxde

water vapour

sulphur gases

carbon monoxide

HAWAIIAN STROMBOLIAN VULCANIAN

Types of eruptions or volcanoes

Eruptions depend on the type of magma (gas content and fluidity of the lava)

The crust thickens.

outer core

mantle

Dorsal ridge or rift valley

Two plates move apart.

rising current

Himalayas

Two plates push together.

Mountain building and relief features

Continental shelves: areas near the coastline, under the sea, made up of continental crust

Relief features

Oceanic (mid-oceanic) ridges: chains of submarine mountains with intense volcanic activity

Great plains: largeextensions of flat land

Mountain ranges:chains of mountains

Ocean trenches: the deepest areasof the ocean

Submarine volcanoescan create volcanic archipelagos.

Abyssal plains: thelargest plains on the planet

SEDIMENTS

MAGMASEDIMENTARY ROCK

IGNEOUS ROCK

METAMORPHIC ROCK

melting

metamorphism

metamorphismweathering and erosion

weathering

and erosion

wea

ther

ing

and

eros

ion

com

pact

ion

and

cem

enta

tion

melting

mel

ting

cool

ing

The rock cycle