Hazardous Earth Flashcards
Name the earths layers
Crust
Lithosphere
Upper mantle (the asthenosphere)
The lower mantle
The outer core
The inner core
Description of the inner core
Solid ball of iron and nickel
Under huge amounts of pressure
Contains uranium and thorium(responsible for the earths internal energy)
Outer core description
Molten liquid layer of iron and nickel that surrounds the inner core
Heat from the inner core creates convection currents
Mantle description
Largest layer behaves like a dense fluid
The upper layer( asthenosphere) constantly moves and flows due to convection currents
Lithosphere description
Solid rock
0-100 km thick (continental)
6-8km thick ( oceanic
How are convection currents formed
Energy from radioactive decay in the core heats up the lower mantle
The hot liquid becomes less dense than its surroundings so it rises upwards
It becomes more dense, therefore sinks back to the bottom
It is heated back again and the cycle continues
Divergent
Move away
Convergent
Move toward each other —>
Conservative
Slides past each other
What happens when two plates move apart
Magma rises in between the gap lava pours out into the surface
Volcanoes form in areas where lava pours out
Can happen in both continental and oceanic crust
What happens in convergent
The plates move towards each other causing one plate to go under another where the one which Subducts is destroyed always oceanic
Leaves an ocean trench
Friction causes earthquakes
Oceanic crust is melted creating magma
Which causes pressure to build up overtime creating an explosive volcano
What happens when an convergent plate movement occurs between oceanic and an oceanic
The denser one sinks below which may cause islands in the ocean to form
What happens when an convergent plate movement occurs between continental and an continental
Neither sink below instead they rise up wards creating fold mountains ( large steep mountains )
What happens at a conservative plate boundary
They create friction because the move side by side
Is both plates get stuck overtime pressure builds up when the move the create very large earthquakes and tsunamis
What are hotspots
They are areas of volcanic activity not related to plate boundaries
Hot magma from the mantle rise and burn through weaker parts of the crust which can create volcanoes and islands
Shield volcano characteristics
Non-explosive
Fast flowing Runny lava
Has low thickness of lava
Shallow sides
Composite volcano characteristics
Very explosive
Extremely hot gases and ash
Has a very strong pyroclastic flow
What’s used to measure earthquake strength
Richter scale
How do tsunamis form
When an oceanic crust is jolted during an earthquake all the water above is displaced
Water travels fast but with low amplitude
As it gets closer to the coast the sea level decreases so there is friction between the sea bed and the waves
This causes waves to slow down and gain height creating a tsunami
how can you predict when a volcano is likely to erupt
Seismometers, which measure vibrations in the ground near a volcano, when they are high there is a strong chance of an eruption
Which factors affect the amount of damage done by an earthquake?
The level of development
The population density
Building infrastructure
How many deaths were there at Haiti?
around 300,000 deaths and 300,000 injured
How many people were made homeless by the Haiti Earthquake?
1.5 million were made homeless
Describe the Volcanoes divergent plates form
Non-explosive, Runny and fast lava, basaltic lava. usually shield volcanoes
Describe the Volcanoes Convergent plates form
Very explosive, thick slow lava, andesitic lava. usually composite volacnoes
Describe the Volcanoes conservative plates form
No volcanoes as no crust is being destroyed and no magma generated
Describe the earthquakes formed in divergent plates
Smaller earthquakes as there is less friction. (5-6 on Richter scale)
Describe the earthquakes formed in convergent plates
Very strong earthquakes. they may be deep underground making them weaker. (up to 9.5 on Richter scale)
Describe the earthquakes formed in conservative plates
Very strong earthquakes, they can be shallow meaning that they could cause more damage. (up to 8.5 on Richter scale)
