1. Types of plate margin There are 2 types of crust:
Continental crust which is older, thicker and less dense than…
Oceanic crust which is younger, thinner and denser
There are 3 directions of movement between plates:
Converging: where 2 plates are moving towards each other
Diverging: where 2 plates are moving away from each other
Passive: where 2 plates are moving side by side
There are 6 different combinations of types of crust and directions of movement:
Converging – where oceanic and continental crust converge (destructive)
Converging – where oceanic and oceanic crust converge (destructive)
Converging – where continental and continental crust converge (collision)
Diverging – where 2 plates diverge under the ocean (constructive)
Diverging – where continental crust is diverging (continental rift zones)
Passive – where 2 plates move parallel to each other (conservative)
Each of the 6 combinations above create different tectonic hazards and produce different landforms.

2. 1. Destructive boundary - Continental / oceanic convergence
Description
denser oceanic crust is subducted
friction and heat cause partial melting of the crust
this magma is less dense than the mantle and rises / forces its way through fissures in the lithosphere
Landforms
deep ocean trenches such as the Peru-Chile trench
Fold mountains from rock scraped off the descending plate and folding of the continental crust
Hazards
Violent volcanoes (composite cone) – due to viscous acidic lavas which block the vents in the volcanoes
Powerful earthquakes and tsunamis

3. 2. Destructive boundary - Oceanic / oceanic convergence
Description
2 plates with oceanic crust collide
the densest crust will be subducted
Landforms
Deep ocean trenches e.g. the Marianas trench
Island arcs as volcanoes rise out of the sea e.g. Caribbean,
Hazards
Violent earthquakes and volcanoes

4. 3. Collision boundary - Continental / continental convergence
Description
Subduction of oceanic crust brings 2 continental masses together
Both have a similar density so can’t be subducted
Sedimentary rocks scraped off the old sea floor are compressed together to form young fold mountains
Landforms
Young fold mountains such as the Himalayas (created in the last 40 million years) These are still growing despite erosion
Hazards
Earthquakes as powerful as at destructive margins

5. 4. Constructive boundary – sub-marine divergence
Description
plates are moving away from each other causing the crust to weaken and hot magma to force upwards creating a ridge
in the centre of the ridge, the crust can subside into to magma below creating a valley
the fissures (splits) in the crust provide a route for the more fluid lavas to escape if these continue submarine volcanoes form
Landforms
Mid-ocean ridges
Volcanic islands e.g. Surtsey
Hazards
Volcanoes that tend to erupt with more basic (runny) lava – more frequent & less violent eruptions
Shallow focus earthquakes

7. 4. Rifting – continental divergence
Description
occurs where spreading occurs beneath the continents
the up-welling magma leads to fracturing and rifting
central sections collapse to form rift valleys
volcanoes form where magma forces its way through fissures
Landforms
Rift valleys such as East African Rift valley – these can widen and eventually get flooded by the sea e.g the Red Sea
Volcanoes such as Mt Kilimanjaro & Mt Kenya
Hazards
Volcanoes
Shallow focus earthquakes

8. 4. Conservative boundary – passive movement
Description
plates are moving parallel to each other, no collision or subduction occurs
movement is erratic as plates stick together, pressure builds up and is released in a sudden movement
Landforms
Fault lines such as the San Andreas and Hayward faults
Hazards
No volcanoes
Earthquakes as powerful as at destructive margins

11. Location of main tectonic plates

12. Distribution of earthquakes

13. Location of volcanic activity

14. Location of seismic activity