tectonics Flashcards
where is there a constructive and collision plate boundary
between India and Australia
where is a transform plate boundary present
At New Zealand
what is the Benioff zone
A dipping flat zone where earthquakes are produced by the interaction of a down going oceanic crustal plate with a continental plate.
what is the subduction zone
the place where two lithospheric plates come together, one riding over the other. Most volcanoes on land occur parallel to and inland from the boundary between two plates
whats crustal fracturing
occurs when the Earths crust causes rock to break and fracture under stress and strain caused by seismic waves.
what are constructive/ divergent plate boundaries
where plates move apart from each other
what are destructive / convergent plate boundaries
where lithospheric plate boundaries move together
where are the majority of earthquakes and volcanoes found
on plate boundaries
where do we find Earthquakes with a magnitude of 9 or higher
where convergence of a oceanic plate and continental plate occurs (a destructive plate boundary with subduction)
what are earthquakes called in the middle of plates
intra-plate earthquakes
why do intra-plates earthquakes occur
They are associated with ancient faults (such as the Rhine Rift Valley) in which the solid crust can crack.
Large faults then may turn into new plate boundaries.
why do we find earthquakes at collision boundaries *
collisions of tectonic plates may also fracture the crust well away from the plate boundary which can yield large magnitude earthquakes.
what are hot spots?
volcanic activity near the centre of some plates.
This is either the result of the upwelling of hot molten material from the core/mantle boundary, such as the Hawaiian hotspots or may result from the top of a large mantle plume just under the crust such as seen in the Cape Verde Islands. It is also possible that large meteorite impacts create symmetrical hot spots on opposite sides of the planet when they collide with the Earth.
where are hotspots found
-Hawaii
-Cape Verde islands
what is convection
convection is created in the mantle by heat radiating outwards from the inner core
how is the internal structure of the Earth known
the internal structure of the earth is known based around how the different earthquake (seismic) waves travel through the solid and liquid layers of the Earth.
seismic waves revealed that there are complicated patterns of hot and cold areas
what is the mantle mostly made from
made mostly from peridotite which behaves like a viscous liquid under pressure.
consists of multiple layers with density and mineral differences
describe slab pull
slab pull is where denser oceanic plates are subducted at cold downwelling’s (there is also some suction force).
This subduction may cause the location of cooler mantle areas and the downward movement within the large scale convection pattern
why does the pacific plate move faster than the other plates
The Pacific plate has lots of subduction around its edge
how can plumes impact a countries location
they can push the crust up on a large scale.
The one currently under West Africa may have also caused the Atlantic Ocean and Iceland to form with the creation of mid Atlantic ridge, and split Scotland from North America and Africa from South America.
for the crust what is the:
-Structure
-Temperature
-Density
-Composition
-Physical state
-Seismic waves present
-Structure: oceanic= 7km thick, continental= 70 km thick
-Temperature: oceanic= 400 degrees C
-Density: oceanic= 3.3g/cm^3, continental= 2.7
-Composition: oceanic= basalt continental= granite
-Physical state: solid
-Seismic waves present: surface and body waves able to pass through
