Earthquakes and Volcanos

Question 1

What are tectonic plates?

Answer 1

Huge slabs of rock that form the Earth’s crust and float on the mantle.

Question 2

Name the 2 types of tectonic plate:

Answer 2

Continental

Oceanic

Question 3

What are the features of a continental plate?

Answer 3

Light and thick. They form land.

Question 4

What are the features of a oceanic plate?

Answer 4

Thin and heavy. They form the ocean floors.

Question 5

What is the movement of plates called?

Answer 5

Continental drift. The plates are floating on the magma.

The magma is moving with the convection currents generated by immense heat.

Question 6

What is the name for where tectonic plates meet?

Answer 6

Tectonic plate boundaries.

Question 7

What are the names of the 4 types of plate boundary?

Answer 7

Destructive
Conservative/sliding
Constructive
Collision

Question 8

What are the features of a destructive plate boundary?

Answer 8

Where an oceanic and continental plate boundary meet.

The heavier oceanic plate sinks under the continental plate. Where they meet is known as the subduction zone.

Where the 2 plates rub together this creates friction.

When the forces become too great for friction to restrict the movement of the plates they move abruptly.

This causes an earth quake.

Volcanos could form where there is a gap in the plates at a destructive plate boundary.

Question 9

What is the Earth made up of?

Answer 9

The Earth has four main layers - 
the inner core
the outer core
the mantle
the crust.

Question 10

What is the inner core of the Earth like?

Answer 10

The inner core is 5,500°C - extremely hot.

It is a very dense solid made from iron and nickel.

Question 11

What is the outer core of the Earth like?

Answer 11

The outer core is 2,000 km thick and is a liquid.

Question 12

What is the Earth’s crust like?

Answer 12

The crust is the rocky outer layer of the Earth.

It is thin compared to the other sections, approximately 5 km to 70 km thick.

If the Earth was scaled down to the size of an apple, the crust would be about the thickness of the apple skin.

Question 13

What are the features of a constructive plate boundary?

Answer 13

A constructive plate boundary occurs when plates move apart.

Volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed.

Constructive plate boundaries can be formed between two oceanic or two continental plates.

Question 14

What is an example of a constructive plate boundary?

Answer 14

The mid-Atlantic Ridge.

Question 15

What are the features of a conservative / sliding plate boundary?

Answer 15

A conservative/sliding plate boundary, occurs where plates slide past each other in opposite directions, or in the same direction but at different speeds.

The plates can be both continental or both oceanic.

Friction is eventually overcome and the plates slip past in a sudden movement. The shockwaves created produce an earthquake.

Question 16

What are the features of a collision plate boundary?

Answer 16

Collision zones form when two continental plates collide.

Neither plate is forced under the other, and so both are forced up and form fold mountains.

The Himalayas are a famous example of collision boundaries of the Indo Australian and Eurasian plates moving towards each other to form fold mountains.

Question 17

Give an example of a famous collision plate boundary?

Answer 17

The Himalayas.

Question 18

Give an example of a famous conservative / sliding plate boundary?

Answer 18

The San Andreas fault in California.

Question 19

Give an example of a famous destructive plate boundary?

Answer 19

The Ring of Fire around the Pacific Ocean.

Question 20

What are the names of the tectonic plates?

Answer 20

• Eurasian
• Pacific
• Indo-Australian
• African
• Antarctic
• South American
• North American
• Nazca

Question 21

What are the main features of a volcano?

Answer 21

A volcano is an opening in the Earth’s crust. It allows hot magma, ash and gases to escape from below the surface.

• Magma chamber - large underground pool of magma
• Lava - magma, once it reaches the surface
• Crater - bowl-shaped basin in the top of the volcano
• Vent - central tube which magma travels through
• Secondary cones - eruptions from other vents may build up secondary cones on the flanks
• Ash, steam and gas - material thrown out by the volcano
• Volcanic bombs - larger material thrown out by the force of eruption

Question 22

What are the 2 types of volcano?

Answer 22

Composite

Shield

Question 23

What are the 3 classifications for volcanic activity?

Answer 23

Extinct – Volcano that has not erupted in the last 200 years and will not erupt again.

Dormant – Volcanos that have erupted in the last 200 years but not in the last 200 years.

Active - Have erupted in the last 2000 years and are likely to erupt again.

Question 24

What are the features of a composite volcano?

Answer 24

Composite volcanoes are steep and made from layers of ash and thick sticky lava.

They occur on destructive plate boundaries.

The eruptions are violent. Ash and lava are ejected into the air. Building up layers of ash and lava.

Pyroclastic flows of hot gas and ash travelling at more than 100 miles per hour can flatten and burn everything in its path.

Question 25

Give an example of a composite volcano?

Answer 25

Mount Etna in Italy.

Question 26

What are the features of a shield volcano?

Answer 26

Shield volcanoes are very gently sloped wide and made from layers of thin runny lava.

They occur at constructive plate boundaries.

These eruptions are not explosive and less likely to result in loss of life.

Examples of shield volcano are in Iceland and Mauna Loa in Hawaii.

Question 27

Give an example of a sheila volcano?

Answer 27

Mauna Loa in Hawaii is a shield volcano.

Question 28

Why do people live near volcanos?

Answer 28

Tourists are attracted to see the volcano bringing jobs related to tourism.

The ground is made fertile by the ash fall. It is especially good for growing vines.

Minerals such as gold and diamonds can be found in volcanic areas.

Geothermal energy can be produced from the rising steam for example in Iceland and New Zealand.

Question 29

How can volcanoes be predicted?

Answer 29

A volcano will begin to deform or change shape before an eruption as the magma rises within it. This can be measured by satellites or also by tiltmeters.

Scientists measure sulphur dioxide and carbon dioxide emitted around the volcano. A large rise in these measures means an eruption is imminent.

Small earth quakes around the base of the volcano often precede an earthquake and they can be monitored by seismometers.

Question 30

How can earthquakes be predicted?

Answer 30

Foreshocks of earthquakes can be monitored with seismometers in order to predict a larger quake.

Scientists have found a gas called radon is often released in the hours before an earthquake. A fault line along a plate boundary can be monitored for the emission of radon.

Animals can sense earthquakes much more strongly than humans. In the Asian tsunami elephants in Thailand broke their chains and headed for higher ground an hour before the tsunami hit the coast of Thailand.

Planning buildings to withstand earthquakes can save many lives. In poorer countries they do not have the money to do this and so many more deaths occur.

Question 31

How can we prepare for a volcanic eruption?

Answer 31

Study previous patterns of lava flows and evacuate residents accordingly. This can be recorded on a hazard map.

Settlements may have large trenches called lava dams dug out around them to divert lava and lahars.

Water can be sprayed on lava flows to cool and to divert them away from for example settlements and roads.

Question 32

What determines the severity of damage from an earthquake?

Answer 32

Type of plate boundary. Destructive plate boundaries cause violent volcanoes.

Is the volcano near to a large settlement? If the volcano is near to a large city it will cause more deaths than if it is in a remote area.

The wealth of the country it erupts. An MEDC can afford scientific prediction instruments, a quick organised reaction force and good medical care.