Distribution & causes of Tectonic Hazards
There are several major crustal plates (African Plate), minor plates (Cocos) & micro
plates (Sunda).
These plates move in different directions & at different speeds creating different types
of plate boundary & therefore different tectonic hazards.
Most earthquakes & volcanoes are on plate boundaries.
Intra-plate processes
There are also earthquakes near the middle of plates (intra-plate) which are associated
with ancient faults which resulted from the crust cracking over millions of years.
Newer large faults can be found (East African Rift Valley) which can turn into new
plates.
These are usually associated with smaller magnitude earthquakes
Collisions of tectonic plates may also fracture the crust away from the plate boundary
(Himalayas & Tibetan Plateau), & these may yield large magnitude earthquakes over a
long period of time as the collision slowly takes place & movement is caused along
faults.
There is also some volcanic activity near the centre of plates (hot spots).
This is either the result of the rising of hot molten material from the mantle/core
(Hawaiian & Tristan la Cuhna hot spot) or from the top of a large mantle plume from
under the crust (Nyiragongo & Cape Verde Islands).
It is also possible that large meteorite impacts create symmetrical hot spots on each
side of the planet when they collided.
, Processes moving the Tectonic plates
Convection currents are made in the mantle by heat radiating from the inner core.
The mantle material (mostly peridotite) is under a lot of pressure due to depth & when
heated becomes a viscous liquid.
The mantle consists of multiple layers with different density & minerals so it is
suggested that there could be convection in either the whole of the mantle or several
layers of convection.
The internal structure of the Earth is known due to seismic waves.
Other forces also cause movement. There is a push at the mid-ocean ridges & slab pull
occurs at destructive plate boundaries.
Two huge mantle plumes also push the crust up on a large scale. (The one under West
Africa may have caused the Atlantic Ocean & Iceland to form with the creation of the
Mid- Atlantic Ridge).
The Structure of the Earth
Image from: https://studyrocket.co.uk/revision/gcse-geography-b-edexcel/hazardous-earth/structure-of-the-earth
There are several major crustal plates (African Plate), minor plates (Cocos) & micro
plates (Sunda).
These plates move in different directions & at different speeds creating different types
of plate boundary & therefore different tectonic hazards.
Most earthquakes & volcanoes are on plate boundaries.
Intra-plate processes
There are also earthquakes near the middle of plates (intra-plate) which are associated
with ancient faults which resulted from the crust cracking over millions of years.
Newer large faults can be found (East African Rift Valley) which can turn into new
plates.
These are usually associated with smaller magnitude earthquakes
Collisions of tectonic plates may also fracture the crust away from the plate boundary
(Himalayas & Tibetan Plateau), & these may yield large magnitude earthquakes over a
long period of time as the collision slowly takes place & movement is caused along
faults.
There is also some volcanic activity near the centre of plates (hot spots).
This is either the result of the rising of hot molten material from the mantle/core
(Hawaiian & Tristan la Cuhna hot spot) or from the top of a large mantle plume from
under the crust (Nyiragongo & Cape Verde Islands).
It is also possible that large meteorite impacts create symmetrical hot spots on each
side of the planet when they collided.
, Processes moving the Tectonic plates
Convection currents are made in the mantle by heat radiating from the inner core.
The mantle material (mostly peridotite) is under a lot of pressure due to depth & when
heated becomes a viscous liquid.
The mantle consists of multiple layers with different density & minerals so it is
suggested that there could be convection in either the whole of the mantle or several
layers of convection.
The internal structure of the Earth is known due to seismic waves.
Other forces also cause movement. There is a push at the mid-ocean ridges & slab pull
occurs at destructive plate boundaries.
Two huge mantle plumes also push the crust up on a large scale. (The one under West
Africa may have caused the Atlantic Ocean & Iceland to form with the creation of the
Mid- Atlantic Ridge).
The Structure of the Earth
Image from: https://studyrocket.co.uk/revision/gcse-geography-b-edexcel/hazardous-earth/structure-of-the-earth
