Challenge of natural hazards

Question 1

Natural hazard

Answer 1

A natural event that threatens human life, causes loss of life and causes damage to property

Question 2

Natural hazard categories

Answer 2

Tectonic hazard - Earthquake, volcanoes, tsunamis

Climatic hazards - Tropical storms, flooding, droughts

Question 3

Factors affecting hazard risk

Answer 3

. Education
. Magnitude
. Level of development (HIC&LIC)
. Population density
. Time of day
. Geographical location

Question 4

Structure of the Earth

Answer 4

. Inner core - Solid iron core 5500c
. Outer core - Liquid layer made up of iron & denser then mantle
. Mantle - Semi molten layer that ranges from 5000c to 1300c
. Crust - Outer layer of the earth broken into tectonic plates. Thickness ranges between 6-70km depending on if it’s continental crust or oceanic.

Question 5

Continental crust

Answer 5

. Older, lighter but is permanent so can’t be destroyed
. 30-70km thick

Question 6

Oceanic crust

Answer 6

. Younger, heavier, denser but can be destroyed easily as it’s thinner.
. 6-12km thick

Question 7

What causes plates to move

Answer 7

Convection currents rising an falling
. Heat driven cycles
. Magma in the mantle rises towards the crust with the heat from the core and falls at the crust

Question 8

Earthquake distribution

Answer 8

Occur on lines on plate margins
. Western coast of north and South America.
. All of Asia

Question 9

Distribution of volcanoes

Answer 9

On land & in the sea - along plate margins
. Some are found in the centre of plates called hot spots
E.g ring of fire

Question 10

Conservative plate margin

Answer 10

Tectonic plates slide past each other building up friction and energy whic eventually slips and causes an earthquake.

Question 11

Constructive plate margin

Answer 11

Plates moving apart. These allow mantle to seep through and crest a volcano

Question 12

Destructive plate margin

Answer 12

Margin where oceanic collides with continental. Oceanic sub ducts down into the mantle

Question 13

Epicentre

Answer 13

The point on the ground directly above the focus of the earthquake

Question 14

Focus

Answer 14

Point of origin of an earthquake

Question 15

Magnitude

Answer 15

Size of the earthquake

Question 16

Seismometer

Answer 16

Instrument that responds to ground noises and shaking
. Needle moves to form a seismograph

Question 17

Richter scale

Answer 17

Each level from 1-12 is is 10 times stronger then the previous level
. 1-5 tremors

Question 18

Mercalli scale

Answer 18

12 point scale
. Describes damages seen after the earthquake