Plate Tectonics And Associated Hazards Facts Flashcards
How many tectonic plates are there in total?
Over 50
What is the average annual movement of a plate?
5-10cm a year
How far do the fastest moving plates move each year?
18cm a year
How old is continental crust?
Over 1500 million years old
How old is oceanic crust?
Less than 200 million years old
What is the total length of all the oceanic ridges on the planet?
60,000 km
How high can submarine mountain ranges reach?
3000m
What island was created in 1963 due to an undersea volcanic eruption?
Surtsey, located to the south of Iceland
- Constructive boundary
- Eurasian and North American plates
What is a transform fault?
They are faults which occur at right angles to the plate boundary. The parts of the spreading plates on either side of these faults may move at different speeds, leading to friction and ultimately to earthquakes. These tend to be shallow focus earthquakes.
What can continental divergence form and give an example of this.
Rift valleys e.g. The Great African Rift Valley
When are Rift Valleys formed?
When the lithosphere stretches causing it to fracture into sets of parallel faults
How far does the Great African Rift Valley extend and where does it start and finish?
It extends 4000km from Mozambique to the Red Sea and then north towards Jordan. A total length of 5500km
What occur in some areas in The Great African Rift Valley?
Inward-facing scarps are 600m above the Valley floor
What is the widely accepted cause of the Great African Rift Valley?
It is due to plumes of magma rising from the asthenosphere. This relatively hot magma causes the plates above it to bulge and create horsts such as the Ethiopian highlands.
Name the three types of convergent margin
- Oceanic->continental
- Oceanic->oceanic
- Continental->continental
