EQ 1.1 Distribution Of Eathquakes , Volcanic Eruptions And Tsunamis Flashcards
(27 cards)
What type of boundary is constructive
Divergent
What type of boundary is destructive
Convergent
What type of boundary is conservative
Transform
Whats an example of destructive area
The Peru-chile trench
Example of conservative area
The San Andreas fault
Example of constructive area
The mid-Atlantic ridge
Example of collision area
The Himalayas
What does intra-plate mean
Teh earthquakes that appear in the middle of plates
What is the zone in the pacific ocean and how many of the worlds volcanoes are there
Ring of fire - 90% of worlds volcanoes + 75% of worlds active volcanoes located here
What boundary are there the biggest earthquakes, whereabouts
Stringers at CONVERGENT boundaries where plates collide
Edge of Pacific Ocean
What boundary have the smallest earthquakes
Divergent
What boundary have medium-large earthquakes
Transform
What are earthquakes caused by
The build up and sudden release of tension at all 4 types of plate margin (destructive, constructive,conservative and collision)
Causes of intra plate earthquakes
Old fault lines reactivating
Human activity (mining, fracking)
Isostatic readjustment
Define tsunami
series of large ocean waves caused by the sudden displacement of water, typically due to undersea earthquakes, volcanic eruptions, or landslides.
What palpate boundary is likely to cause the undersea earthquake leading to a tsunami
Destructive (convergent) plate boundary
How to the old fault lines cause an earthquake
Small movements build up friction and strain over time which is then suddenly released causing low magnitude earthquakes
How does an intra plate volcano occur on an oceanic plate
6-10 km thick plate and magma rises through the mantle from the edge of the outer core as it can melt through
Forcing molten material to the surface
Creating volcanoes that rise from the sea bed
How does an intra plate volcano happen at a continental plate
They are much thicker 30-70km but can get stretched enough in places for the magma to form a hit spot, linked to a mantle plume , to break through
Where are the 2 mantle plumes
One centred under the pacific plate and one centred under the African plate
What rises from the outer core in a mantle plume
Molten viscous silicate material
Where do isolated hot spots occur
Where there is an upwelling of molten material directly from the outer core/mantle boundary to the surface - Hawaiian islands
What is a mantle plume
Vertical columns of extremely hot magma that rise up from the mantle
What are mantle plumes caused by
Radioactive decay in the asthenosphere
