By Claire and Demos

Volcanoes

A volcano is an opening in a planet's surface which allows molten rock, ash and gases to escape from below the planet’s surface. The word ’volcano’ is taken from Vulcan, the Roman god of fire.

There are also mud and ice volcanoes not to mention super volcanoes, cinder cones and composite volcanoes. There

are also submarine, subglacial and shield volcanoes as well as lava domes, crypto domes and fissure vents.

Here are some pictures of different types of volcanoes.

What is a volcano?

Subglacial Volcano

Shield Volcano

Lava Dome

Mud Volcano

Super Volcano

Ice Volcano

Some volcanoes occur when two plates meet. When two plates collide and one plate is forced beneath the other plate, the friction makes the

first melt and magma rises up. Only some volcanoes on earth are formed like this, but their eruptions are the most violent and are the most

dangerous.

How are some volcanoes formed?

How are underwater volcanoes formed?

Underwater Volcanoes are formed when the surface of the Earth tears apart. The ocean surface is congested and creates pressure on the surface which concludes in the surface actually cracking

forming an underwater volcano.

When you measure the magnitude of an earthquake you are measuring the size and the extent of it. The magnitude of an earthquake is measured on the Richter magnitude scale. This

scale is also known as the local magnitude. This scale assigns a single number to express the amount of built up

stress released by an earthquake. The effective limit of measurement for local magnitude ML is about 6.8. Even though

the Richter scale is still used it has been replaced with the moment magnitude which conveys similar results.

Did you know that an earthquake that measures 5.0 on the Richter scale is ten times larger than

one that is measured at 4.0?

What does magnitude mean?

Richter Magnitude

Description Earthquake Effects

Frequency of

occurrence

Less than 2.0

2.0 to 2.9

3.0 to 3.9

4.0 to 4.9

Micro

Minor

Minor

Light

Micro earthquake

not felt.

About 1,000 each year.

Often felt but rarely

causes damage.

Generally not felt but still

recorded.

49,00 each year.

Noticeable shaking of

indoor items, rattling noises.

8,000 each day.

6,200 times each

year.

Deep within the volcano it is so hot that some rocks slowly melt and become a thick flowing substance (magma). Because magma is lighter than solid rock around it, it rises and collects

in magma chambers inside the volcano. Eventually some of the magma is forced up through cracks, fissures and holes in

the ground and finds its way into the main vent of the volcano.

When the magma is half way up the main vent it turns into lava. The heat of the lava (750°C) burns the remaining rocks

from the magma as it continues to get hotter and hotter while it is rising up the main vent. Once the lava reaches the crater

of the volcano a volcanic eruption occurs.

How do volcanoes erupt?

Here are some soundsDry Lava Fast

Lava

Lava Powerful Lava

Sound of Lava

Stromb

Underwater Volcano

2sec

3sec

3sec

5sec

5sec

13sec

36sec

Pressure of the gas within the earth's crust can cause a volcano to erupt. An earthquake can also cause a volcanic eruption. This happens when the earths surface moves (an

earthquake) and forces the magma to move up into the chambers of the volcano until it hits the main vent and

explodes.

What causes a volcanic eruption?

Cross section

Cross Section

The ring of fire is an invisible ring that covers most of the pacific

ocean. It shows where most volcanoes are.

What is the ring of fire?