Presentazione per CLIL medie Scienze

2. Volcanoes are formed when molten, sticky rock called
magma, forces its way through a crack in the Earth’s crust.
The melted rock that spills out of the crater on the top of
the volcano is called lava. The lava destroys everything in
its path because it is very, very hot!

3. Watch this video and take notes!
https://www.youtube.com/watch?v=vfRwd1ML6yw
What are volcanoes?
How many types of volcanoes are there?

4. Where do
volcanoes
happen?
Most volcanoes
are formed on
land, but there are
some volcanoes
that are on the
ocean floor. Some
of these volcanoes
emerge from the
water because
they are very high.
Why does a volcano erupt?
A volcano erupts when magma and
gases find a way to escape, so they
burst to the surface through a vent.
An eruption can be quite gentle or
very violent.

5. Types of volcano
Volcanoes can be active, dormant or extinct.
• A volcano is active, or alive, when it erupts often.
• When a volcano is dormant, or sleeping, it has not
erupted for a long time – but it might in the future.
• A volcano is extinct, or dead, when it hasn’t erupted
for at least 100,000 years.

6. Video
Continue watching the video.
https://www.youtube.com/watch?v=vfRwd1ML6yw
• This time pay attention to the places where volcanoes
occur.
Take notes!

7. Where do volcanoes occur?
Volcanoes occur at:
1. Hotspots
2. Plate Boundaries
-Convergent (subduction zones)
-Divergent

8. Where do volcanoes occur?
Hotspots
Spot on Earth with volcanism
Can occur in the middle of tectonic plates
Hotspots don’t move
Tectonic plates move over hotspots
Make a chain of volcanoes, like Hawaii

9. Where do volcanoes occur?
Hotspots
Hawaii

10. Where do volcanoes occur?
Convergent plate boundaries – where two of Earth’s plates join
together or one moves under the other (subduction zone)
 Most major volcanoes are found near subduction zones
 Stratovolcanoes
 Most dangerous
Two different types:
1. Ocean-Ocean
2. Ocean-Continent

11. Where do volcanoes occur?
Ocean-Ocean
Island Volcanic Arcs
Japan
Aleutian Islands, Alaska

12. Where do volcanoes occur?
Ocean-Continent
Continental Volcanic Arcs
Andes Mountains, South America
Cascades, N.W. United States

13. Where do volcanoes occur?
Divergent plate boundaries – where two of Earth’s plates move
apart
RING OF FIRE (belt along the Pacific Ocean)

14. Famous volcanoes
Can you name some famous
volcanoes?
Watch the video!
https://www.youtube.com/wa
tch?v=vfRwd1ML6yw
Do the worksheet!
Etna, Sicily

15. Famous volcanoes
Where are these volcanoes?
Guess!
Work in groups!

16. Structure of a volcano
Watch this video and write as many parts of the volcano as you can!
https://www.youtube.com/watch?v=YS7_mGZeG_Q

17. Structure of a volcano
Ocean-Continent
Continental Volcanic Arcs
Andes Mountains, South America
Cascades, N.W. United States

18. Structure of a volcano
Ocean-Continent
Continental Volcanic Arcs
Andes Mountains, South America
Cascades, N.W. United States
magma
central
vent
side vent
lava
old layers
of lava
ash cloud
Earth’s crust

19. Structure of a volcano
Some definitions:
Magma – the molten, or liquid-like, rock within the Earth
Lava – magma that reaches Earth’s surface
Vent – an opening through which molten (liquid-like) rock
flows onto Earth’s surface
Volcanoes always have one central vent, but can also have
several smaller side vents.

20. Types of volcano
There are three major types of volcanoes:
 Shield volcanoes
 Composite volcanoes
 Cinder cone volcanoes

21. Types of volcano
 Shield volcanoes
• The magma inside a shield volcano is rich in iron
and magnesium and is very fluid.
• Since the magma is very fluid, the lava coming
out of the volcano tends to flow great distances.
• When shield volcanoes erupt, the flowing lava
gives the volcano the shape of a gently sloping
mountain.

22. Types of volcano
 Shield volcanoes
• Eruptions of shield volcanoes are mild and
can occur several times.
• Mauna Loa in Hawaii is an example of a
shield volcano.

23. Types of volcano
 Composite volcanoes
• The magma inside a composite volcano is rich in silica
and much thicker than magma from a shield volcano.
• Gases get trapped inside this thicker magma.
• Eruptions from composite volcanoes can be flowing
lava or explosions. The explosive eruptions come from
the trapped gases and produce cinders and ash.

24. Types of volcano
 Composite volcanoes
• These different types of eruptions are what give
composite volcanoes their alternating layers of
lava and cinders.
• Composite volcanoes have much steeper slopes
than shield volcanoes.
• Mount Fuji in Japan and Mount St. Helens in the
USA are examples of composite volcanoes.

25. Types of volcano
 Composite volcanoes

26. Types of volcano
 Cinder cone volcanoes
• The magma inside a cinder cone volcano has
large amounts of gas trapped in it.
• Eruptions from cinder cone volcanoes are violent
and explosive because of all the gas trapped in
the magma.
• The large amounts of hot ash and lava thrown out
of the vent fall to the ground forming the cone
shape that these volcanoes have.

27. Types of volcano
 Cinder cone volcanoes

28. Eruptions
Viscosity, together with the amount of gas
dissolved in magma, can determine the
explosivity of the eruption. More viscous
magma with volatiles is more explosive
than less viscous magma, where gases
can bubble out relatively easily.

29. GLOSSARY
Bomb – a lump of rock thrown out in an eruption
Crater – a deep hollow at the top of a volcano
Crust – The top layer of the Earth
Eruption – the release of gases, magma and rock from a volcano
Lava – melted rock that flows down the volcano
Magma – melted rock inside the Earth
Molten – melted, liquid
Vent – a crack on the side of a volcano where magma can escape

30. Experiment 1: viscosity
What is viscosity?
•It is the resistance to flow in a fluid or liquid

31. Experiment 1: viscosity
Instructions:
•Explore the viscosity of different household liquids by timing how
fast paperclips travel through different fluids!
•Observe that more viscous fluids are “thicker” and harder for
objects like paperclips (and gas bubbles) to travel through.
•Compare the fluids to different magmas and determine whether
the magmas would be explosive or non-explosive.

32. Experiment 1: viscosity
Items:
• Graduated cylinders, 10-100 ml
• Paperclips
• Dish Soap
• Syrup
• Cooking Oil
• Water
• Strong magnets (3-4)

33. Experiment 1 viscosity
• Work in groups!
• Fill in your worksheet while
experimenting!
• Remember! More viscous magma with
volatiles is more explosive than less
viscous magma, where gases can bubble
out relatively easily.
•

34. Experiment 2: Soda Bottle
Demonstration
• Purpose: to provide an example of a
volcanic eruption using everyday items,
showing how gases behave when dissolved in
a liquid and how pressure and agitation affect
the dissolved gases.

35. Experiment 2: Soda Bottle
instructions
-Take an unopened soda bottle > Since the
bottle is unopened and under pressure, there
should be no evidence of carbonation.
-Twist off the cap
-Place the balloon over the bottle opening.
-Tape the balloon to the bottle so it does not
pop off.

36. Experiment 2: Soda Bottle
Demonstration step 1
• Does the bottle have any gas in it?
• Can you see it? why?

37. Experiment 2: Soda Bottle
Demonstration step 1
All the gas is dissolved in the liquid. So, it is
invisible because the soda is under pressure
and the gas elements are in a liquid phase.
This is exactly how gases behave in magma.
When under pressure, volcanic gases are
dissolved in the magma but will expand and try
to escape when pressure is released.

38. Experiment 2: Soda Bottle
Demonstration step 1
In fact… what happens if you shake a soda
bottle and then open it?
The bottle will “explode” when
opened.

39. Experiment 2: Soda Bottle
Demonstration step 2
What’s happening?
• Within a minute, the balloon will stiffen and
will show signs of filling with gas (If the bottle
is left alone for an hour or so, the balloon will
be visibly inflated)

40. Experiment 2: Soda Bottle
Demonstration step 2
Why?
When the pressure is reduced, the gas in the
soda leaves the liquid and travels to the
balloon. This effect mirrors what happens
when magma rises closer to the Earth’s
surface. The pressure is reduced and gases
will try to escape.

41. Experiment 2: Soda Bottle
Demonstration step 3
What happens if you shake the bottle?

42. Experiment 2: Soda Bottle
Demonstration step 3
The agitation of the bottle mirrors the effects of
an earthquake. Gases will leave the liquid at
a greatly increased rate. Earthquakes can
trigger volcanic eruptions by agitating the
magma, and causing dissolved gases to
leave the solution.

43. GROUP WORK: 3D model

44. 3D model
• You will need:
• A small plastic drinks bottle (without lid)
• Newspaper
• White glue
• Water
• A bowl
• A large cardboard box
• Scissors (always supervise kids when they’re using
scissors)
• Paint and brushes

45. 3D model
• Instructions

46. 3D model
• Cut a large square out of your cardboard box to make
the base board.
• Using white glue, stick the bottom of the drinks bottle
to the base board.
• Rip half of the newspaper into inch-wide strips.
• In a bowl, create a mixture of thin white glue and
water.
• Scrunch up sheets of the remaining newspaper,
submerge it in the glue mixture and stick it on to the
cardboard around the base of the bottle.
• Continue to use scrunched-up newspaper to build up
the volcano around the sides of the drinks bottle.

47. 3D model
• Next, dip strips of newspaper into the glue mixture
and lay them on the top of each other, covering the
scrunched-up paper, from the bottle opening to the
cardboard base.
• Add several layers of torn paper until the shape
resembles a volcano.
• Leave to dry for at least 24 hours.
• Once the paper mache is completely dry, use paint to
decorate the volcano.

48. 3D model

49. 3D model
• How to Make Lava:
• Using the funnel add two or three tablespoons of
bicarbonate of soda to the bottle in the centre of the
volcano.
• Next, add a couple of drops of red food colouring.
• Finally – get ready for your volcano to erupt – and add the
white vinegar!

50. 3D model
• How to Make Lava:
When you add vinegar to bicarbonate of soda a chemical
reaction occurs – the result is ‘carbonic acid’. This is an
unstable substance – you can tell from all the fizzing! The
mixture instantly separates into a gas and a liquid,
producing carbon dioxide and water

51. 3D model