Natural hazards

Question 1

what is a natural hazard

Answer 1

a natural event or process which causes loss of human life and/or damage to property

Question 2

what is a hazard risk

Answer 2

the chance or probability of being affected by a natural event

Question 3

factors affecting people’s risk from natural hazard

Answer 3

poverty
urbanisation
climate change
population growth

Question 4

how does poverty increase the risk from a natural hazard

Answer 4

as people in poverty often make their homes in high risk areas and are made with cheaper materials as it is all they can afford

Question 5

how does urbanisation increase the risk from a natural hazard

Answer 5

as there is not enough space in cities and they are very densely populated so when hazards (e.g earthquakes) occur, buildings can collapse which then causes lots of homes to be destroyed

Question 6

how does climate change increase the risk from a natural hazard

Answer 6

as if the atmosphere gets hotter, there is an increased chance of hazards (e.g drought or famine) occurring and if it gets a lot wetter, the sea levels may rise and cause an increase in flooding and tsunamis

Question 7

how does population growth increase the risk from a natural hazard

Answer 7

as more people will need homes and since there is less space available for housing, people may be forced to live in high risk areas

Question 8

what are the types of natural hazard

Answer 8

hydrological events (flooding)
meteorological events (storm)
geophysical events (earthquakes)
climatological events (drought)

Question 9

layers of the earth

Answer 9

crust
lithosphere
mantle
outer-core
inner-core

Question 10

features of the crust

Answer 10

8-65km thick
made of basalt and granite

Question 11

features of mantle

Answer 11

mesosphere (lower)
asthenosphere (upper)
1000-3700 degrees
2900km thick
84% of earth’s volume
made of olvine and peridotite

Question 12

features of outer-core

Answer 12

made of iron and nickel
2300km thick
4400 degrees
liquid metal

Question 13

features of inner-core

Answer 13

made of iron and nickel
solid metal
1220km thick
4.5 billion years old
6000 degrees

Question 14

features of continental crust

Answer 14

lighter
less dense
made from granite
more buoyant
has land on it
25-75km thick

Question 15

features of oceanic crust

Answer 15

heavier
denser
made from basalt
less buoyant
has sea on it
7-10km thick

Question 16

what does a converging plate do

Answer 16

move together

Question 17

what does a diverging plate do

Answer 17

move away

Question 18

how does a convection current happen in the mantle

Answer 18

the heated magma in the mantle rises as it is less dense and as it rises, it cools and becomes denser again - causing it to sink and then heat up and so on

Question 19

what is ridge push

Answer 19

mid ocean ridges are higher than the rest of the ocean floor so gravity causes the ridge to force the plate down

Question 20

what is slab pull

Answer 20

tectonic plates are heavy so when a plate has started to sink, gravity and the fact that it is dense means that it will pull the rest of the oceanic crust down with it

Question 21

where do volcanoes happen

Answer 21

there is a long line of volcanoes in the Pacific ocean
not many in Europe
few in the middle of the Pacific
plate boundaries

Question 22

where do earthquakes occur

Answer 22

on tectonic plate boundaries
Asia (e.g Philippines)
some random places (e.g Australia)

Question 23

what is a constructive plate margin

Answer 23

a gap appears between two tectonic plates and they pull away from each other due to ridge push and slab pull
molten magma rises to fill the gap and cools to create a solid rock and new crust
this creates a mid-ocean ridge of mountains as the magma is buoyant and pushes the crust upwards
sometimes this new rock fractures as it moves and causes a gentle, shallow earthquake close to the surface
sometimes lava escapes, usually as a gentle volcanic eruption causing shield volcanoes

Question 24

how does a destructive plate margin occur

Answer 24

a plate with oceanic crust moves towards one with continental crust, which crumples to form fold mountains
the denser oceanic crust is subducted under the continental crust by slab pull - leaving a deep oceanic trench above
as the plates converge, pressure builds up and eventually the rocks fracture which causes strong earthquakes
deep in the mantle heat and pressure melt the subducted oceanic crust which rises as magma towards the surface
as the magma rises, it becomes viscous which causes violent volcanoes with steep sides

Question 25

how does a conservative plate margin occur

Answer 25

two plates try to move side by side as either end of the plate is pulled or pushed
friction makes them stick so movement becomes increasingly difficult
pressure steadily builds up as the two plates try to move past each other
eventually, the pressure becomes too great and the rocks fracture, allowing the two plates to slip past each other
this causes strong earthquakes (but no volcanoes as there is no gap for magma to escape from)

Question 26

factors that affect hazard risk

Answer 26

Population density
Urbanisation
Level of development
Human activities
Frequency of the hazard
Magnitude
Prediction
Planning

Question 27

factors that affect risk of a natural hazard

Answer 27

Population density
Increased numbers of people in hazard prone areas
Urbanisation
Frequency
Magnitude
Level of development
Prediction
Planning
Human activities

Question 28

why are more places prone to natural hazards

Answer 28

Lack of education
People do not know what do to in hazard event to stay safe
Lack of planning
Emergency services are not prepared
Low level of development
Leads to a lack of resources to deal with the hazard impacts
Lack of resources to rebuild
Location in areas which have more natural hazards
They don’t have the opportunity to recover