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Flashcards in EQ1-tectonics Deck (21)
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What is the earths structure

Crust-Outer shell of the earth

Mantle-the widest layer of the earth. The upper part is solid but below the rock is semi molten.

Outer core-

Inner core-


What are seismic waves

Shock and aves released by tectonic movements


What is convection currents

Plates move because they are dragged along by powerful convection currents in the soft rock in the mantle


What is plate tectonic theory pt1

Mantle convection-responsible for plate movement. In mantle convection heat produced by decay of radioactive elements in the earths core heats the lower mantle creating convection currents

Slab pull-Major driving force for plate movement. Newly formed oceanic crust at mid ocean ridges becomes denser and thicker as it cools. This causes it to sink into the mantle
Subduction-as new crust is being created in one plate it’s being destroyed by another by subduction. As two oceanic plates move towards each other one slides under the other

Seafloor spreading-Huge mid ocean ridges are forced when hot magma is forced up from asthenosphere and hardens. The crust pushes the tectonic plates apart


What are the 3 types plate boundaries

Convergent-where two plates collide
Divergent-where two plates move apart
Conservative-where two plates slide past each other


What is the Benioff zone

-The area where friction is created between colliding tectonic plates resulting in intermediate and deep earthquake
-A flat zone of earthquakes that is produced by interaction of a sub-ducting oceanic crustal plate with a continental plate
-these earthquakes can be produced by slip along the subduction thrust fault or slip on faults within the sub-ducting plate as a result of bending and extensions as the plate is pulled into the mantle


What are some primary effects of earthquakes

Crustal fracturing-when energy released during an earthquake causes the earths crust to crack leaving gaps
Ground shaking-buildings, bridges, roads and infrastructure to collapse
Liquéfaction-the violent shaking during an earthquake causes surface rock to lose strength and became liquid than solid


What are some secondary effects of earthquakes

-The ground shaking places stress on slopes so that they fail resulting in landslides rock slides mudslides and avalanches
-liquefaction can make rescue efforts more difficult and disrupt underground power


What are some primary social effects of Haiti

220,000 people killed
300,000 people injured
8 hospitals were badly damaged or destroyed
Displaced people were moved into tents


what is a divergent plate boundary

is a linear feature that exists between two plate that are moving away from each other.


what is a convergent plate boundary

this is where one plate slides beneath the other causing a process known as subduction.


what is conservative plate boundary

conservative plate boundaries occur when plates slide past each other in opposite directions but without creating or destroying lithosphere


what is slab pull

slab pull is driving force fro plate movement. its when mid ocean ridges becomes denser and thicker as it cools this causes it to sink into the mantle under its own weight.


what is liquefaction

the violent shaking causes surface rocks to loose strength and become more liquid than solid. the subsoil loses its ability to support building foundations.


what is pyroclastic flows

a mixture of dense hot rock, lava, ash and gases ejected from a volcano which move very quickly across the earth's surface. they destroy everything they touch


what are lahars

masses of rock, mud and water that travel quickly down the sides of volcanoes. they are caused when an eruption quickly melts snow and ice.


What are jökulhlaup

The heat of a volcanic eruption can melt the snow and ice in a glacier. These floods can be very dangerous because they suddenly release large amounts of water, rock, gravel and ice that can catch people unaware


How are tsunamis formed

Cause by submarine shock waves generated by earthquakes or volcanic eruptions.


Why are some impacts of tsunamis

-large tsunami can travel inland for several miles sweeping buildings,bridges and roads, uprooting trees and destroying farmland
-they also wash away soil undermining the foundations of buildings, bridges and roads uprooting trees and destroying farmland


Why was the 2004 Indian Ocean tsunami so destructive

-The earthquake that caused the tsunami was especially large
-there were no warning systems out in place
-many of the countries affected are lower income countries


what does type of plate boundary depend on?

motion: whether plates are moving apart(divergent),colliding(convergent) or sliding past each other(conservative)
plate type:whether the tectonic plates are oceanic or continental. oceanic plates make up