A
How do volcanoes happen?
A big crack develops in the Earth’s crust.
------- travels up the crack and shoots out or erupts on the surface of the Earth.
Magma
Once the magma erupts onto the surface, the magma is called------
Lava
The lava will stop flowing, and then it cools and hardens into ------
rocks
Lava can be very hot, sometimes ------°C.
1000°C
Why do Japan, Indonesia and the Philippines have such a high risk of volcanoes?
because they have cracks in the Earth’s crust that allow magma to erupt.
Mention an island that was made by volcanoes?
Hawaii
Why is it called the Pacific Ring of Fire?
because there are many active volcanoes along it.
Around which ocean are there many volcanoes?
The Pacific Ocean
Mention countries with a high risk of volcanic eruptions?
Indonesia, Japan and the Philippines
Why do some areas have a low risk of a volcanic eruption?
because they have no cracks in the crust.
Mention 2 negative effects for volcanoes?
1-Ash covers buildings and crops. People become ill when they breathe in ash and poisonous gases.
2-Lava burns and buries crops and buildings.
3-People can be injured or killed by ash and hard lumps of lava.
Why do some areas of the world have a high risk of a volcanic eruption?
because there are many cracks in the Earth’s crust in these areas.
Mention 2 positive effects for volcanoes?
1-Underground water is heated by magma. This water comes to the surface as hot as springs. These are tourist attractions.
2-Lava makes good soil. Ash fertilises the soil. Crops grow very well.
3- Underground water in volcanic regions is hot enough to heat people's houses.
What are the 2 types of volcanoes?
Composite and volcanic plateau
The ash and lava build up a ------------- mountain with smooth sides.
cone-shaped
The most common type of volcano is a ----------
composite volcano.
The composite volcano has layers of ----- and -----
ash and lava
The ash is ---------
burnt lava.
Some of the magma forces its way through cracks in the sides of the volcano. When this magma erupts it forms baby volcanoes called ---------
secondary cones.
The islands of ------ in the Pacific Ocean are made of layers of lava.
Hawaii
All these materials flow up a -------
central pipe, or vent.
The layers of lava form a flat surface called ----------
a volcanic plateau.
Besides lava, some volcanoes send out -------, ------- and ------
rocks, volcanic ash and gases.
During the eruptions, the vent widens at the surface to form a -------
crater