Tectonic Hazards

Question 1

Tectonic theory

Answer 1

the movement of the plates and the activity inside the Earth

Question 2

Plate margins/boundaries (4)

Answer 2

1-Constructive-pulling apart/diverging
2-Destructive- moving towards each othe/ subducting
3-Collision-moving towards each other and rumpling
4-Conservative- side by side/lateral movement

Question 3

Volcanoes forming at Destructive plate boundaries

Answer 3

-two plates are moving together
-the denser plate subducts and goes beneath the less dense plate
-friction between the plates cause STRONG earthquakes
-as the oceanic plate subducts it melts
-creating magma which is LESS fluid than at a constructive plate boundary
-It breaks through the surface to form steep sided composite volcanoes
(very violent and explosive eruptions)

HOWEVER this does not apply if two continental plates collide as no subduction occurs fold mountains are made so no volcanoes/no magma.

Question 4

Volcanoes forming at Constructive plate boundaries

Answer 4

-two plates are moving apart
-magma forces its way to the surface
-as it breaks through the thin crust it creates shallow earthquakes
-as it reaches the surface it creates volcanoes
-the magma (BASALT LAVA) is very hot and fluid so travels further before cooling forming broad, flat shield volcanoes
(when under water the magma erupts as pillow lavas)

Question 5

Convection currents

Answer 5

hot spots cause hot rising plumes of magma within the mantle, called convection currents

Question 6

How do the Earth’s tectonic plates move?

Answer 6

1-convectional currents- convection currents reach the base of the crust, diverge and move laterally under the crust because they can’t break through. Pulling the crust apart. The magma cools, sinks and is sucked back into the convection current again.
2-gravitational slide when the subducting plate drags the adjoining plate.

Question 7

The global distribution of active volcanoes

Answer 7

Mainly around destructive plate margins but less at the constructive margins