Flashcards in EQ1-tectonics Deck (21)
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.
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