Restless Earth Flashcards
What is the definition of a natural process
An event which happens on the earth’s surface due to a range of factors, e.g. gravity, temperature
What is the definition of a natural hazard
A natural process which has the potential to harm or injure humans, e.g. floods, typhoons, earthquakes
What is a natural disaster
A natural hazard where either 10+ die, 100+ are affected or there is $1million worth of damage caused by the natural process.
What happened on 26/12/04
Indian Ocean eq and tsunami
Large tsunamis and eqs swept through islands around the pacific ring of fire, killing 227,000
What happened to mt Krakatoa in the 1880s
The volcanic island erupted for 7 months, with explosions of volcanic gas being heard every 10 minutes, leaving Indonesia devastated with 36000 deaths.
What is the name of the land mass which was formed by all of the continents fitting together
Pangea
What is continental drift
The theory which suggests that the continents once formed Pangea, first theorised by Alfred Wegener and later proved by connecting bands of fossils left in corresponding regions.
Who was Alfred wegener
A meteorologist who theorised continental drift, but had no ways of proving it
Who was Arthur Holmes
A geologist who suggested that continental drift was caused by convection currents
Who was Harry Hess
a professor who sailed across the Atlantic with sonar technology in the 1960s and discovered the mid Atlantic Ridge
Who were Fredrick Vine and Drummond Matthews
Geologists who took rock samples from the mid- Atlantic ridge and found out that their ages were mirrored on each side.
Where are most volcanoes and earthquakes
On plate boundaries and cracks in plates
What is a divergent plate boundary
Where two plates move apart
What is a convergent plate boundary
When two plates move towards each other
What is a transform boundary
When two plates rub against each other
What is a plate boundary
Where two plates meet
What is subduction
When an oceanic plate sinks under continental plate
What is a fold mountain
Mountains that form when two plates fold up after colliding
What is an ocean trench
A deep, narrow ditch formed at destructive boundaries
What is the difference between lava and magma
Lava is molten rock on the earth’s surface, magma is molten rock below the surface.
Name 5 natural hazards
Earthquakes
Volcanoes
Typhoons
Hurricanes
Tsunamis
What is continental crust
Thicker, less dense crust made out of mostly granite
What is oceanic crust
Thinner, denser crust made out of basalt
Name the layers of the earth from inside out
I. Core, O. Core, mantle, crust
What is the earth’s crust
The outermost layer, made of basalt and granite. It is 8-65km thick
What is the mantle
Makes up most of the earth, made of Mg, Si, O, Al.
Is a viscous fluid
Describe how convention currents work
Outer core heats up magma
The less dense magma rises
As the magma reaches the surface, it spreads out, dragging the plates with it
The magma cools and sinks
Where two plates are pulled together, they will either overlap or fold up
Name the 13 plates
N. American
Pacific
Nazca
S. American
Coco
Caribbean
African
Eurasian
Arabian
Indian
Australian
Philippine
Antarctic
Describe what happens at a conservative plate boundary
The plates are sliding past, in opposite or the same directions, but at different speeds
As they slide past each other, tension is built up over time and released as earthquakes
An example of this is the San Andreas fault between the N. American boundary and the Pacific plate.
Describe what happens at a destructive (convergent) plate boundary
Convection currents move two plates towards each other, and the oceanic plate subducts under the continental crust, as it is more dense, forming an ocean trench
When it sinks into the mantle due to convection currents, friction occurs and the heat and pressure build up.
The hotter and lighter magma rises to the surface, creating fold mountains, volcanoes and earthquakes as the magma jolts when breaking through the crust.
An example of this is the Nazca (oceanic) and S. American boundary(continental)
Describe what happens at a constructive (divergent) plate boundary
Convection currents move plates in opposite directions
As the plates are pulled apart, magma rises due to convection currents, forming volcanoes
The volcanoes can continually erupt, growing with each cycle
This can form a ridge over continuous eruptions, e.g. the mid- Atlantic Ridge.
Describe what happens at a collision plate boundary
Two plates of a similar density move towards each other
When they crumpled, they form fold mountains
This can also cause earthquakes to appear
An example of this is the Himilyas
