MY Geography 🌏 Flashcards
4 Evidence to support plate tectonic theory
Jigsaw fit, convectional currents, fossils, geological patterns
What is the evidence of a jigsaw fit between the continents?
They all fit together
What is plate tectonic theory?
The theory that the earth’s crust is made up of large plates moving in constant slow motion. Convection currents in the mantle move the plates. The source of heat driving the convection currents is the radioactive decay which is happening deep in the earth.
What is an example of a jigsaw fit in continents?
East of South America and West of Africa
How does jigsaw fitsupport plate tectonic theory?
If all the plates fit together at a certain point, they would’ve had to move to be broken up like they are today
What is proof of convection currents?
Underwater volcanoes and mountains show something is pushingor pulling the Earth.
How do convection currents support the plate tectonic theory?
It provides a cause for the pushing and pulling of the earth.
What is an example of how the study of fossils has helped support plate tectonic theory?
Mesosaurus fossils found on west coast of africa and east coast of south america only
How does the study of fossils support plate tectonic theory?
It shows the continents were likely connected as the mesosaurus could not have swam or flown across the ocean.
What is an example of geological patterns supporting plate tectonic theory?
Coal deposits in antarctica
Why does coal being in antarctica support plate tectonic theory?
Coal is fossilised plants. Plants currently don’t grow in Antarctica so they must’ve at a certain point.
Which geologist proposed the idea of one big content being formed which he called pangaea?
Alfred Wegener
What are the names of the plates?
Pacific, NA, SA, Eurasian, African, Phillipine, Juan de fuca, indo-australian, antarctican, nazca, cocos. arabian, caribbean
Three types of boundaries
Divergent, Convergent (destructive) , Transform
What is oceanic crust?
plate that is made up of more dense rock. It sinks easily due to its
density and is constantly created at boundaries. It is ‘new
rock’ and forms our ocean bed.
What is a subduction zone?
where one plate is forced downwards below another plate and
grinds past it causing huge amounts of friction and heat.
What is a convergent (destructive) plate boundary?
where two plates are moving towards each other, one of which is
continental crust and one is made of oceanic crust
What is continental crust?
this is a plate that is made up of less dense rock. Because it is less
dense it doesn’t sink. It is exceptionally old and makes up our land
surfaces
What is a plate boundary?
where two very large crustal plates meet on the earth’s surface.
Earthquakes and volcanoes happen here.
What are fold mountains?
large mountain ranges formed by the collision and ‘folding’
of two plates as they plates continually push into one another.
What is an Ocean trench?
a particularly deep point of the ocean bed where the oceanic and
continental crust have dragged each other downwards.
What is a composite volcano?
very steep
volcano which is formed at a
destructive boundary. The
magma under the surface has
high silica and is very explosive –
these are the most dangerous
What are pyroclastic flows?
Pyroclastic flows are fast-moving currents of hot gas and rock, which reaches speeds moving
away from a volcano of up to 450 mph. The gas can reach temperatures of about 1,000 °C.
Pyroclastic flows normally hug the ground and travel downhill, or spread laterally under gravity.
What is a volcanic bomb?
A volcanic bomb is a mass of molten rock larger than 64 mm in diameter, formed when
a volcano ejects viscous fragments of lava during an eruption.
Volcanic bombs can be thrown many kilometres from an erupting vent, and often acquire
aerodynamic shapes as they cool during their flight. The largest have been evidenced in
Japanese eruptions, up to 6 metres in diameter.
What are properties of lava flows?
Lava flows destroy everything in their path, but
most move slowly enough that people can
move out of the way. Speeds can reach
30mph if it is low viscosity (runny) e.g.
Mauna Loa, Hawaii
What are lahars?
- Lahars are when a snow-capped volcano erupts, melting the snow and ice.
- They have the thickness of wet concrete, and travel at 30 miles per hour.
- This scalding water travels down the volcano, and eventually mixes with mud and debris from surrounding forests and communities.
What causes tsunamis at destructive plate boundaries?
- caused by the sudden uplift of the oceanic plate which displaces huge amounts of water.
- When these reach land, they can cause waves up to 30m high and can kill over 300,000 as it did in the Indian Ocean Tsunami.
What are some hazards of a volcano?
Pyroclastic flows, volcanic bombs, volcanic ash, lava flows, lahars,
What is an earthquake
Earthquakes are vibrations of the Earth’s crust caused by movement at
plate boundaries and major fault lines.
Where do earthquakes happen?
Earthquakes can occur at all major fault boundaries but the most
severe are usually conservative and convergent (destructive).
What is the epicenter?
The point on the surface above where an earthquake
happens is called the epicentre.
What is the focus?
The point along the fault in
the crust where an earthquake
happens is called the focus.
What are the two ways to measure an earthquake?
Richter and Mercalli Scale
What does the richter scale measure?
measures the magnitude of
the earthquake (how much the ground
shakes)
What does the mercalli scale measure?
measures the intensity of
the earthquake (based on observations of
the resulting damage)
What is a logarithmic scale?
Every 1.0 is ten times more powerful than the previous 1.0 . Eg) 5.0 = 4.0 x 10
What instrument is used to measure magnitude of an earthquake?
Seismometer
How does the mercalli scale measure?
Roman numerals from I - XII
How does the Richter scale measure?
1-10 logarithmic scale
What is a primary wave?
- arrive first and fast.
- Moves through solid rock and fluids, pushes and pull in the direction of travel.
- These move at about 8km per second and transfer energy from the focus to epicentre
What is a secondary wave?
- slower than primary waves,
- only move through solid rock
- These move at about 4km per second
- transfers energy from the focus to epicentre
What are love waves?
These (along with Rayleigh waves) arrive
approximately 20-30 seconds after the P&S waves. They only travel
through the surface crust and do so in a rolling motion. The ground
moves side to side. Responsible for most of the shaking felt by
people.
What are Rayleigh waves?
only travel through the surface of
the crust, fastest waves
Delete later
Delete later
What were some human factors that made the Haiti earthquake so destructive?
- Population density
- level of development
- building standards
What is a super volcano?
a volcano 1000x times bigger than a regular volcano that
has the potential to produce an eruption with major effects on the global
climate and ecosystems.
What caused the Indian Ocean tsunami in 2004?
1) Indo-Australian plate boundary subducts under the Eurasian plate boundary which slips and causes a 9.1 magnitude earthquake.
2) It dislodges the water and it ripples getting larger, converging and slowing down as it approaches shallow water, the wave spreads
3) affects 12 countries across the indian ocean.
What are some ways to predict volcano eruptions?
GPS, gas samples, rock samples, temperature, seismographs
How do you protect from earthquakes?
‘Birdcage’ steel frame, computer controlled counter weight, rubber shock absorbers
How do you prepare for earthquakes?
Earthquake drills, emergency survival kit,
What layer of the earth is the thickest?
Mantle
What layer of the earth is the hottest?
Inner core
What theory did Alfred Wegener have about plate movement?
Jigsaw fit
What is an example of a divergent (constructive) plate boundary?
Iceland
How thick is the crust?
5-70km
How thick is the outer core?
2300km
How thick is the inner core?
1250km
How hot is the mantle?
1000°C near the crust, 3700°C near the outer core
How hot is the outer core?
3700°C-5000°C
How hot is the inner core?
5000°C+
What is the mantle made of?
Flowing semi-molten rock
What is the outer core made of?
Semi-liquid iron
What is the inner core made of?
Solid Iron and nickel
How do earthquakes and volcanoes happen at convergent boundaries?
Two plates move towards eachother as a result of convection currents which is achieved by energy from radioactive decay in the earth’s inner core heats up the mantle.
The Oceanic plate is more dense than the continental plate as a result the oceanic plate sinks below. Huge amounts of prssure occurs at the subduction zone. Plates get jammed together and they are suddenly released, causing an earthquake.
The friction causes melting of the oceanic plate in the mantle. The extra molten rock rises upwards due to being denser than the molten rock around it. The molten rock is very viscous because it has high silica and often gets stuck in the volcano underground. Eventually the pressure rises and a violent eruption takes place.
What are the world’s major plates?
Pacific, NA, SA, Eurasian, African, Indo-Austrailian, Cocos , Juan de Fuca, Nazca
GO DO THE PLATE LOCATIONS SHEET ON GOODNOTES
please
What caused the Haiti earthquake?
Earthquake on the conservative fault between the Carribean and NA plate
What magnitude was the Haiti earthquake?
Magnitude 7
How deep was the focus of the Haiti earthquake?
8-10km
Where was the Haiti earthquake?
15km southwest of Port-au-Prince
What were some impacts of the Haiti 2010 earthquake?
105k houses destroyed
316k dead
300k+ injured
1.5m homeless
$7.9b damage
What were some responses after the Haiti 2010 earthquake?-
- rescue teams took 2 days
- $1.1b charity donations
- many countries sent search and rescue teams
Why did population density make the Haiti 2010 earthquake worse?
In the capital the population more than 500 people per square km. This led to the earthquake effecting more people because the earthquake’s epicentre was 15km from the capital, Port-au-Prince
Why was the building codes in Haiti a factor in making the Haiti 2010 earthquake a human disaster?
Because of Haiti’s lack of building codes, buildings were made with unstable materials and frames. As a result, this made them prone to collapsing in the place of an earthquake. When the 2010 earthquake happened, many buildings collapsed which led to more damages, deathes and injuries
Why was Haiti’s wealth a factor to why the Haiti 2010 earthquake was a human disaster?
Haiti couldn’t afford to use stronger building materials to make less buildings collapse
What is a volcano?
An opening or crack in the lithosphere
What is a superpower nation?
A superpower is an extremely powerful country, especially one capable of influencing events and policies of less powerful countries. Its power can be felt all over the world.
What factors make a superpower?
Geographic size, population, resources, military power, economic power, cultural power, political power,
What are the BRIC nations?
Brazil
Russia
India
China
What are the MINT nations?
Mexico
Indonesia
Nigeria
Turkey
What is continental drift?
The movement of the earth’s continents
What is a fault line?
place where there is a long break in the rock that forms the surface of the earth and where earthquakes are more likely to happen.
What is a primary effect?
An effect that is immediate
What is a secondary effect?
An effect that isn’t immediate
What properties does high silica lava have?
Very thick
What is an example of a supervolcano
Yellowstone
Why is Mexico an emerging superpower?
- next to US
- young average age (28)
- 1.2t USD ecomony
What makes Indonesia an emerging superpower?
- Population (250 million)
- Young age (29)
What makes nigeria an emerging superpower?
Average age (18)
Running at a surplus
Currency is stable
Large oil reserves
Opening up to more FDI
What makes Turkey an emerging superpower?
Population (74 million)
Young age (29)
Good location (between europe and asia)
