Restless Earth Knowledge Flashcards by owen brewster

What is the thicker type of crust

Continental

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Which Type is the older type of Crust at 4.3 billion years old

Continental crust

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Which way do the plates move at a destructive boundary

Towards each other

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In which boundary do the plates move away from each other

Constructive

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Conservative margins move…

Side to side of each other

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Name the features that can occur at a destructive boundary

Composite volcanoes
Earthquakes
Fold mountains
Ocean trenches

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Constructive boundries create…

Shield volcanoes

Volcanic islands

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Describe what happens in a subduction zone

The lighter continental plate stays on top whilst the heavier oceanic crust is pushed down where it melts

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Describe briefly the three stages in the formation of a fold mountain

Sediment forms a thick layer in a geosyncline
The sediments have great pressure in them and solidify
The plates move towards each other forcing the rock up

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What is an anticline

The peak of a mountain

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Why aren’t ocean trenches any use to humans

To deep to harvest any products from

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How are earthquakes measured in:
A) the Richter scale
B) the mercali scale

a) seismographs

B) human judgement

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What does the Richter scale measure and how

The magnitude and in a logarithmic scale from 1-10

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What numerical system is used by the mercali scale

Roman numerals

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Describe three physical factors that increase the impact of an earthquake

High magnitude
Shallow focus
Weak foundations eg sand and clay

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Describe four human factors that decrease the impact of an earthquake

Low population density
Non residential area
Good housing regulations
Frequent drills

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Describe a composite volcano in five points

Steep 
Narrow base 
Viscous lava 
Made of lava + ash 
Irregular eruptions

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Describe a shield volcano in five points

Gentle slopes 
Wide base
Runny lava
Only made up of lava 
Frequent but inexplosive eruptions

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How many times bigger is a supervolcanos eruption than a regular volcano

1000 times bigger

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What two global effect would a super volcano eruption have on earth

Global dimming

Global cooling

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Define focus

The underground centre of the earthquake

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“The point directly above the focus”‘is a definition of what

The epicentre

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How do shockwaves move

They radiate out from the focus in all directions

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Name the four stage process in which a tsunami is caused

Two plates get stuck the. Lose their tension suddenly
An underwater earthquake occurs
Sea bulges up
Waves move towards land

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Which is the denser type of crust?

Oceanic

Describe oceanic crust in 4 points

Newer Denser Sink able Can be renewed

Describe continental crust in 4 points

Older Less dense Can't sink Cannot be renewed or destroyed

Where are constructive margins most common

Under the ocean

What occurs at constructive plate boundaries

Shield volcanoes Small earthquakes Formation of new land

What type of manga comes from constructive margins

Runny lava

At a destructive margin which plate subducts under which plate

Oceanic goes under the continental

What happens to the oceanic crust in the subduction

It melts and forms magma

Why forms a destructive plate boundaries

Ocean trenches Composite volcanoes Fold mountains Earthquakes

What is a collision margin

A destructive boundary In which both plates are made of continental

What forms at collision margins and give an example

Fold mountains eg Himalayas

In a conservative plate boundry describe the movements of each plate

Both plates are going overall in the same direction. One plate may be going faster and so they rub past each other

How are earthquakes distributed

In linear patterns along plate boundaries

How are volcanoes distributed

In linear patterns along plate boundaries and hot spots

Where do over half the worlds earthquakes occur

Pacific ring of fire

What is the first stage I the formation of a fold mountain

Sediment settles under the ocean in a geosyncline

What are the second and third steps of the fold mountain formation

The sediment forms sedimentary rock then the destructive plates push it together forcing the rock up

How deep are ocean trenches

5000-10,000 meters

What is the Benioff zone

Where earthquakes occur in a destructive boundry

Why is the lava coming from shield volcanoes more runny

Because it has a low silica content

Shield volcanoes are made only from...

Lava

Shield volcanoes erupt ...

Frequent

How are composite volcanoes formed

In the subduction zone of a destructive boundry a pool of magma forms, pressure pushes this up through cracks. Thus causing an eruption, the lava is high silica and so solidifies quickly, over eruptions it builds up

Composite volcanoes are formed by

Ash and lava

What are lahars

Mudflows formed by the mixing of water and volcanic ash

Why do people live near volcanoes

Fertile soils Tourist attractions (hot springs geysers) Geothermal power Valuable minerals (sulphur, borax, pumice)

What minerals can be found in volcanoes

Diamonds, borax, pumice

What are the signs a volcano eruption is going to happen

Small earthquake Steam and gases out of the crater The crater bulges The temperature changes

What is a tiltmeter

A bit of kit to measure slight changes in a volcanoes profile

What is the main way volcanoes can be predicted in the long run

Historical records

Where d super volcanoes occur at

Hot spots

What is the name for the large depression in which a super volcano is formed

A caldera

After the eruption what happens to the user volcanoe

It collapses into the caldera

Where is the focus

Exactly at the origin of the earthquake (underground)

Where is the epicentre of an earthquake

The point directly above the focus on the ground

Why is prediction hard for earthquakes

It's very hard to tell when it's going to happen

What do the Chinese and Japanese do to predict earthquakes

Monitor animal behaviour

Why are the primary and secondary waves less powerful

Because they are underground

What physical factors decrease the damage of an earthquake

Low magnitude | Deep focus

What human factors increase damage done by an earthquake

Population density Residential area Self built housing Lack of response

How can houses be protected from earthquakes

Steel frames that move with earthquake Fire resistant materials Well built foundations Shock absorbers

What starts a tsunami

Earthquakes at sea

Why do the waves of tsunami get bigger towards the coast

Because they slow down

Low silica content lava is Also known as what and is found where

Basic lava and in shield volcanoes

High silica content is also know as what and is found where

Acidic lava and is found at composite volcanoes

Restless Earth Knowledge Flashcards

(69 cards)