Tectonic Hazards

Question 1

Describe the core of the earth:

Answer 1

Extremely hot and under a lot of pressure.

Question 2

What is mantle?

Answer 2

A solid materials that flows very slowly and surrounds the core.

Question 3

What is the asthenosphere?

Answer 3

The upper portion of the mantle which is a weak layer and can deform like plastic.

Question 4

What is the lithosphere?

Answer 4

The crust and upper mantle form a rigid shell at the surface of the Earth.

Question 5

How can movement of plates be tracked?

Answer 5

Using GPS.

Question 6

What is a plate margin?

Answer 6

Where 2 plates meet.

Question 7

What are 2 reasons why tectonic plates move?

Answer 7

-Convection
-Ridge push and slab pull

Question 8

What is convection?

Answer 8

The core’s temperature is around 6,000C. This causes magma to to rise in the mantle and sink towards to the core when it cools.

Question 9

What is ridge push?

Answer 9

At constructive margins, ocean ridges form high above the ocean floor. Beneath ocean ridges the mantle melts; the molten magma rises as the plates move apart and cools down to form new plate material. As the lithosphere cools, it becomes denser and starts to slide down, away from the ridge, which causes plates to move away from each other.

Question 9

What is slab pull?

Answer 9

At destructive margins, the denser plate sinks back into the mantle under the influence of gravity, which pulls the rest of the plate behind it.

Question 10

What are the 3 types of plate margins?

Answer 10

Constructive, destructive and conservative.

Question 11

What is convection?

Answer 11

The core’s temperature is around 6,000C. This causes magma (molten rock) to rise in the mantle and sink towards the core when it cools. The currents flow beneath the lithosphere, building up lateral pressure and carrying the plates with them.

Question 12

Where are earthquakes found?

Answer 12

At all 3 plate margins.

Question 13

Where are volcanoes found?

Answer 13

On constructive and destructive plate margins.

Question 14

What is the Ring of Fire?

Answer 14

A large band of volcanoes and earthquakes which circles the pacific ocean.

Question 15

What are ‘hot spots’?

Answer 15

Sometimes earthquakes and volcanoes occur in the middle of plates, where the Earth’s crust is thought to be particularly thin.

Question 16

Give an example of a hot spot:

Answer 16

Hawaii has formed due to volcanic eruptions at a hot spot that is located far from the edge of the Pacific plate.

Question 17

How do earthquakes form at constructive plate margins?

Answer 17

When the risen molten magma cools it forms solid rock, this can sometimes fracture as it is moved, causing earthquakes.

Question 18

How do volcanoes form at constructive plate margins?

Answer 18

The upper part of the mantle melts and hot molten magma rises. As the plates move away from each other, the molten magma rises in between and cools to form solid rock. In a few places, the magma erupts on to the surface, producing a lava that is runny and spreads out before solidifying. Over many eruptions a volcano with a typically wide base and gentle slopes, known as a shield volcano, is formed.

Question 19

What are rift valleys?

Answer 19

On land, constructive plate margins form a steep-sided valley known as a rift valley, where the land drops as plates move apart.

Question 20

Give an example of a rift-valley?

Answer 20

The Mid-Atlantic Ridge.

Question 21

Which plate is denser?

Answer 21

The oceanic plate.

Question 22

Which plate is subducted at a destructive margin?

Answer 22

The denser oceanic plate.

Question 23

Name 3 things that occur at destructive plate margins:

Answer 23

-Earthquakes
-Fold mountains
-Volcanoes

Question 24

Why do earthquakes happen at destructive plate margins?

Answer 24

As the plates converge, pressure builds up. The rock eventually fractures, causing an earthquake, which can be very destructive.

Question 25

Give 5 economic reasons for living at risk from tectonic hazards?

Answer 25

-Geothermal energy
-Farming the nutrient-rich soils helps agriculture
-Mining provides energy and income
-Tourism creates jobs and provides income
-It may be cheaper to stay than move

Question 26

Give 3 social reasons for living at risk from tectonic hazards?

Answer 26

-People want to stay near friends and family
-The threat may not be great enough, or people don’t understand risk
-People are confident that the buildings will keep them safe

Question 27

What are 4 ways to monitor a volcanic eruption?

Answer 27

-Changes in shape of ground and volcano using tiltmeters and GPS satellites
-Earthquakes near magma chambers using seismometers
-Ground surface and river temperatures using thermal heat sensors
-Radon and sulphur gas using gas-trapping bottles

Question 28

Which is easier to predict, volcanoes or earthquakes?

Answer 28

Volcanoes, as they usually as they usually give advance warning signals before erupting.

Question 29

What are 2 ways to protect against a volcanic eruption?

Answer 29

-Buildings can not be designed to completely protect against eruption impacts
-Evacuation instructed by authorities

Question 30

What are 4 ways to plan for a volcanic eruption?

Answer 30

-Evacuation
-Exclusion zones
-Education to know what to do
-First-aid training

Question 31

Which is harder to monitor, volcanic eruptions or earthquakes?

Answer 31

Earthquakes.

Question 32

What are 2 ways to monitor an earthquake?

Answer 32

-Foreshocks using seismometers and GPS
-Radon using radon detection devices

Question 33

What are 2 ways to protect against an earthquake?

Answer 33

-Building and transport infrastructure (eg foundations with rubber shock bearings) though these are expensive
-Sea walls in case of tsunamis

Question 34

What are 3 ways to plan for an earthquake?

Answer 34

-Practise drills
-Preparing emergency supplies and location of evacuation centres
-Securing objects/furniture