1.2 Tectonic Hazards

Question 1

The Earth’s core

Answer 1

Centre layer

Split into two layers:
Inner metallic core (solid)
Outer core (liquid)

The hottest part of the Earth

Question 2

The Earth’s mantle

Answer 2

Surrounds the core

Semi-solid rock, which is molten and can move

Question 3

The Earth’s crust

Answer 3

Very thin outer shell

The layer we live on

Between 5- 100 km thick

Floats on the mantle

Question 4

Tectonic plates

Answer 4

Slabs of rock, composer the Earth’s crust

Question 5

Continental plates

Answer 5

Thicker
Older
Lighter

Do not subduct

Question 6

Oceanic plates

Answer 6

Thinner
Younger
Denser

Subduct under other plates

Question 7

Plate boundaries

Answer 7

The location where tectonic plates meet

Question 8

Convection currents

Answer 8

Occur in the upper mantle

The core heats molten magma that rises and hits the underside of the plate, causing it to move

The rising magma cools and falls back down but more heated magma pushes up and further moves the plate

This causes the plates to be pushed apart or pulled together

Question 9

Conservative plate margins

Answer 9

Plates sliding past each other

Question 10

Destructive plate margins

Answer 10

Oceanic plates slides beneath continental plates

The point at which this happens is called a subduction zone

Question 11

Conservative plate margins

Answer 11

Plates diverging

The convection currents diverge and cause a gap to form between the plates

Magma rises up to fill the gap that is created between the two plates

Question 12

Earthquakes at conservative plate margins

Answer 12

The plates are made of rock that has jagged edges so they catch and snag

Friction and pressure between the plates builds until the plates can’t take the stress

They slip past each other, which can cause both plates to move and, as a result, there might be an earthquake

Question 13

Earthquakes at destructive plate margins

Answer 13

The rocks catch against one another as the plates are not smooth surfaces

The pressure between the plates builds until the plates can’t take the stress

They slip past each other, which can cause both plates to move and, as a result, there might be an earthquake

Question 14

Volcanic activity at destructive plate margins

Answer 14

The friction and pressure from subduction causes vents to form in the continental plate

The magma rises to the surface of the Earth through the cracks in the continental plate

This usually creates highly explosive volcanoes that produce a lot of gas and lava (e.g. Mount Vesuvius in Italy)

Question 15

Volcanic activity at constructive plate margins

Answer 15

The divergence of the plates creates outward pressure

Magma bubbles up to fill the gap between the plates, creating a volcano

This kind of volcano is common in Iceland

Question 16

Hot spots

Answer 16

Hotspots do not happen at plate boundaries

Occur on parts of the crust over hotter parts of the mantle

The rising hot air weakens the Earth’s crust and magma can reach the surface, bubbling up through the weakness in the crust

The Hawaiian islands all formed as a result of a mid-Pacific hotspot

Question 17

Lava

Answer 17

Magma that is above the Earth’s surface

Question 18

Gas

Answer 18

Volcanoes emit lots of gases (e.g. carbon dioxide, sulfur)

Question 19

Ash

Answer 19

Burnt rock fragments that are blown into the atmosphere, usually at some force

Question 20

Volcanic winter

Answer 20

When a volcano erupts and produces lots of ash that blocks out the sun

Mount Pinatubo’s 1991 eruption reduced global temperatures for 3 years

Question 21

Pyroclastic flows

Answer 21

Currents of hot ash, lava and gas that can move downhill at speeds of up to 500km/h during an eruption

Impossible to outrun

Can reach temperatures of up to 1000C

Can cover distances of up to 30km from the volcano