1.1 Global Distribution Of Hazards

Question 1

What happens at a convergent plate boundary?

Oceanic Continental

Answer 1

• Oceanic plate is subducted as it I’d less dense which creates deep oceanic trenches.
• fold mountains may also be created as the CC is pushed upwards
• oceanic plate is melted in the Benioff zone creating thick andesitic lava with many salt and mineral ions from the water in the ocean

Question 2

What happens at a convergent plate boundary?

Oceanic and Oceanic

Answer 2

• Denser and faster plate is subducted beneath the other
• ocean trench is made
• subducted plate melts creating magma which can rise through faults
• volcanoes grow and rise above the surface to form separate islands called island arcs or atolls

Question 3

What happens at a convergent plate boundary?

Continental meets Continental

Answer 3

• collision margin occurs
• neither plate is subducted (a more compacted plate can be subducted slightly) as they have the same density and are both less dense that the asthenosphere
• sediment crumbles and is forced upwards
• shallow focus earthquakes

Question 4

Explain the structure of the earth

Answer 4

• mantle is this top part made of the plates
• mantle is where the convection current takes place
• outer core is semi molten and provides heating for magma plume
• inner core is made of solid iron at 6000C

Question 5

Explain what happens at a divergent plate boundary.

Answer 5

• two plates move apart from slab pull
• meaning magma can rise through the centre
• often happens underwater forming mid oceanic ridges e.g. Atlantic
• submarine volcanoes are found here meaning is,ands can grow above sea level
• can create rift valleys where stretches and the centre collapses

Question 6

Explain what happens at a Conservative plate boundary.

Answer 6

• two plates grind past each other where this results in a major break releasing energy as an earthquake
• powerful earthquakes occur here but no plate is created or destroyed

Question 7

What is an intraplate earthquake?

Answer 7

• major ancient fault lines or faults extending into the centre of the plate can cause an earthquake if the plate they are in is put under stress
• they can also channel seismic waves from the main boundary, the waves travel up the fault into the centre of the plate

Question 8

what happens at an intraplate hotspots?

Answer 8

• Magma plume is hotter than usual and exploits a fault

- basaltic lava volcanoes can grow, often out of the water making a new island arc like Hawaii this is called an Atoll