distribution and physical processes- natural hazards

Question 1

tectonic plate

Answer 1

a rigid segment of the earth’s crust that can float across the heavier semi-molten rock below

Question 2

plate margin

Answer 2

the margin or boundary between two tectonic plates

Question 3

• describe destructive margins

Answer 3

two plates move towards each other. Here the dense oceanic plate is subducted beneath the less dense continental platel. friction causes strong earthquakes. the sinking oceanic plate creates sticky, gas-rich magma. this results in steep- sided composite volcanoes which erupt violently.

where two continental plates meet there is no subduction, so no magma to form volcanoes. the crust crumples and lifts to form fold mountains. Powerful earthquakes can be triggered

Question 4

• describe contructive margins

Answer 4

the two plates move apart and magma forces its way to the surface. As it breaks the crust it causes mild earthquakes.

the magma is very hot and fluid allowing the lava to flow a long way before cooling. this results in typically broad and flat shield volcanoes

Question 5

• describe conservative plate margins

Answer 5

two plates move past each other at different rates. friction between the plates build stresses and trigger earthquakes when they slpi, there are no volcanoes because there is no magma.

Question 6

• describe tectonic plates

Answer 6

the earths crust is split into seven major and several monor tectonic plates

there are two types of crust- dense, thin oceanic crust and less dense, thicker continental crust 

plates move , drivewn by convection currents within the mantle and inder gravity

Question 7

what is a natural hazard?

Answer 7

A natural event that threatens people or has the potential to cause damage, destruction and death.

Question 8

distribution of volcanoes

Answer 8

volcanoes are large, often cone-shaped landforms, formed over long periods by several eruptions. they are fed by molten rock deep within the earths mantle

Like earthquakes, most volcanoes occur in belts along plate margins. but some occur at hot spots where the crust is thin and magma breaks through the surface

Question 9

the pattern of earthquakes

Answer 9

an earthquake is a sudden, violent period of ground shaking.

most occur at the margins of slow moving tectonic plates.

friction and sticking between plates create enormous pressures and stresses which build to breaking point