Tectonic Processes And Hazards Flashcards
(29 cards)
What are the 5 types of plate boundaries?
-destructive
-constructive
-transform (conservative)
-collision
-complex
Describe a constructive plate boundary with an example
Where two plates (usually oceanic) diverge.
Example: between the Nazca and Pacific Plates
Describe a transform (conservative) plate boundary and give an example
When two plates move alongside each other, so conserving their size.
Example: between the pacific and north American plates
Describe a collision plate boundary and give an example
When two CONTINENTAL plates converge.
Example: between Altiplano and South American plates
Describe a complex plate boundary and give an example
Where several types are found along a relatively short distance.
Example: north-east of Caribbean plate
What is the pacific ‘ring of fire’
Its the eastern part of the pacific where there are varying sizes of tectonic plates and types of plate boundaries
What are the 3 causes of tectonic hazards
-volcanic
-earthquake
-tsunamis
How do volcanos cause tectonic hazards
Volcanoes, often explosive, are found in the Andes fold mountains because unstable mantle material and melted oceanic plate force their way to the surface.
• Gentle volcanic activity is found at constructive plate boundaries as mantle material moves upwards to fill the gaps left by diverging plates, for example, between the Nazca and Pacific plates.
Where are explosive volcanos found?
Andes fold mountains
An example of gentle volcano activity causing tectonic hazards
Between the Nazca and pacific plates
How do earthquakes cause tectonic hazards
Constructive plate boundaries only have small earthquakes, as there is not much friction or strain as plates diverge.
• Transform plate boundaries (conservative) have a large amount of friction, and when strain is neleased the shockwaves can be strong.
-Converging plates create the largest amount of friction and strain, with earthquake focal points following the Benioff zone to considerable depths.
How do tsunamis cause tectonic hazards?
depths.
* An upward oldownward movement of the crust must disturb a mass of seawater.
This movement will be associated with an undersea carthquake, and so is usually linked to a destructive (convergent) plate boundary
What is an intra-plate processes
Earthquakes and volcanoes are also found towards the middle of a plate (intra) away from the boundaries.
Where can earthquakes happen
-They can happen anywhere the crust is cracked.
-isostatic readjustment
-human activities
How can cracks in the crust cause intra-plate earthquakes
-Cracks in the crust are usually ancient faults created by previous plate movement.
-small movements along these old faults build friction and strain which when released causing low magnitude earthquakes
What is isostatic readjustment and how does it cause intra-plate earthquakes
It is the weight of ice removed after the ice age.
It can cause earthquakes as the earth crust moves up or down
How does human activity cause intra-plate earthquakes with an example
Human activity can also trigger tremors;
Examples:
- weight of water in a reservoir
-fracking of gas
-large explosions
Where can intra-plate volcanoes occur
Volcanic activity can be found in the both the MIDDLE of OCEANIC and CONTINENTAL plates.
How do intra-plate volcanoes occur on oceanic plates?
-oceanic plates are 7km thick.
-magma rising through the mantle from the edge of the outer core is able to melt its way through, forcing molten material to the surface, creating volcanoes that grow from the seabed.
How do intra-plate volcanoes form on continental plates
-continental plates are thicker than oceanic plates.
-but they get stretched enough in places for the magma from a hot sport, linked to a mantle plume, to break through and form a volcano
Case study of an intra-plate earthquake
-the United Kingdom
-the UK experiences minor earthquakes despite being 1500km from the nearest plate boundary under the centre of the Atlantic ocean.
-there about 25 earthquakes in the UK each year that are felt by people.
-the largest occurred in 1931 under the North Sea at Dogger Bank (6.1 on the richter scale)
Largest intra-plate earthquake in the UK
1931
North Sea at Dogger Bank
6.1 on the richter scale
Case study of intra-plate volcanoes
-Hawaii
-Hawaii islands have 15 volcanoes
-These 15 are the youngest of 130 found along a 6000km line to their north west.
-Kilauea and Mauna Loa are the most active volcanoes on the planet.
-the submarine volcano Lo’ihi is the youngest in the Hawaiian chain, being created as the pacific plate moves north-westwards over the hot spot
Which volcano is the youngest intra plate volcano in the Hawaii chain
the submarine volcano Lo’ihi is the youngest in the Hawaiian chain, being created as the pacific plate moves north-westwards over the hot spot
