Hazardous Earth Flashcards
What’s the features of the layers of the earth
Inner core-solid metal, solid, under lots of pressure
Outer core-liquid nickel and iron, molten rock
Mantle-largest layer, rigid ad the top but the bottom (asthenosphere) is semi molten and can flow
Crust-thinnest layer and can be dense continental core or a oceanic crust that is less dense
Why is heat distributed differently
As the Earth is heated differently so there’s a difference in air pressure. Winds blow from areas of high pressure to areas of low pressure so heat transfers away from the equator
There are cells (loops) and they have warm rising air creating low pressure belts and cool falling air which crates high pressure belts
Why does a tectonic plate move
Due to convection currents in the mantel
What happens when tectonic plates move
Lower prt of the asthenosphere heats up and becomes less dense and rises to the top of the asthenosphere and as it cools down it becomes denser and sinks
Thus created circular movements of semi-molten rock called convection currents creating a drag.
What are convergent boundaries
Two plates move towards each other. When a continental and oceanic plate meets the denser oceanic plate is forced down to the mantel and is destroyed creating earthquakes, volcanoes and ocean trenches. When two continental plates meet they collide and the ground folds to forced upwards to create mountain ranges.
What are divergent boundaries
When two plates move away from each other so magma rises from the mantel and fills the gap and cools to create new crust and so volcanoes can form.
What are conservative boundaries
Where two plates move sideways past each other or in the same direction at different speeds but the crust isn’t destroyed.
What are composite volcanoes
When lave is vivacious is builds up the sides of mountains then cools and makes the mountains steep in shape. The occur along convergent plate bound so they are move likely to be violent. It can trap hot gases and suddenly release and cause pyroclastic flow.
What are sheiks volcanoes
This forms when lava is more fluid and is unable to build on sides or volcanoes. So there tend to have more of a spread out base. They are found on divergent plate boundaries and not as violent.
Hazards of volcanoes: what is lava
It’s molten rock and can erupt as lava flows when it is runny or as steep-sided domes when it us viscous.
Lava may destroy buildings but moves relatively slowly so it’s a rare threat to people
Hazards of volcanoes: pyroclastic flow
Hot avalanches of rock, ash and gas travels down volcanoes slopes at high speeds
Hazards of volcanoes: Lahars
Hot or cold mixtures of water and volcanos debris which form when materials interact with water, ice or snow. Lahars are most dangerous bear volcanoes but large Lahars travel a long way from a volcanos so ur can pose a threat to people
Hazards of volcanoes: volcanic gases
Bubble out of lace or escape from soul or vents in the ground. Most common is water vapour, carbon dioxide and hydrogen. Some are poisonous over long periods of time they can account for climate change.
