Earthquakes, Volcanos, Tsunamis Flashcards
Name the seven main plates
Indian plate African plate Australian plate Eurasian plate American plate Nazca plate Pacific plate
How many main plates are there
Seven
What sort of boundary is it if two plates pull apart
Constructive boundary
What sort of boundary is it if two plates collide
Destructive boundary
What sort of activity can take place at plate boundaries
Volcanic
Earthquakes
Mountain building
Why do the plates move on the magma
The core heats up the magma in the mantle and this sets up convection currents
What was the super continent called before continental drift
Pangea
Where does volcanic activity take place
Most of the time it’s on plate boundaries
What is a mid-ocean ridge
A chain of mountains underwater
Give an example of a mid-ocean ridge
The mid Atlantic ridge and it’s about 16000km long
How are mid ocean ridges formed
When two plates separate magma rises from the mantle through cracks or fissures of the crust between the two plates. When the magma reaches the water it cools and solidifies to form a new ocean floor. This happens over and over again to form a chain of mountains under the sea
Give an example of a volcanic island
Iceland
How are volcanic mountains formed
They are formed when magma form a hole in the crust called a vent as the magma is under so much pressure in the mantle most eruptions are violent.
Where are volcanic mountains usually placed
On plate boundaries
What erupts from a volcanic mountain
Magma,ash, has, rocks, steam and boiling mud
What is an active volcano and give an example
A volcano that is still erupting at regular intervals
Ex: mount Etna, Mount St. Helens
What is a dormant volcano and give an example
A volcano that hasn’t erupted in a few hundred years but may still erupt in the future
Ex: Mount St. Helens was a dormant volcano until it erupted in 1980
Or Mount Fuji is still active but has not erupted since 1707
What is an extinct volcano and give an example
A volcano that hasn’t erupted in recorded times (thousands of years)
Ex: Slemish mountain co. Antrim
Where are more than half of the worlds volcanos located
The pacific ring of fire
What is an earthquake
A sudden trembling of the earths crust and this takes the form of a series of shocks and tremors
What is the focus of an earthquake.
The point deep in the earths crust where the earthquakes begin
What is the epicentre of an earthquake
The point directly above the focus on the surface. It’s the place where the tremors are the strongest
What scale is used to describe the damag e or strength of an earthquake
The Richter scale
What is the instrument used to measure the strength of an earthquake
Seismograph
How much stronger is an earthquake each time it moves one number up on the Richter scale
x10
How does a tsunami happen
When there is an earthquake under the sea a giant wave called a tsunami can occur
How are fold mountains formed
They are formed when two plates collide the heavier plate is forced down into mantle. Continental plates rocks buckle in a series of folds. The rocks are forced upwards forming the mountain shape with anticlines and synclines
Give an example of fold mountains and the plates that caused the rocks to buckle.
The Andes
Nazca and the South American plates
Name some mountain ranges that were formed during the alpine folding period
The Andes
The Himalayas
The Rockies
The Alps
What period of folding were the irish fold mountain ranges formed
Amorican period of folding
Give ways to reduce the damage caused by earthquakes
Build earthquake resistant buildings in earthquake zones
Study past earthquake patterns and try to forecast when the next one might occur
Have fund set aside for repairs due to earthquakes to speed up recovery process
Organise evacuation process for town
What damage does earthquakes cause
Bridges roads, rail are damaged- makes it difficult to get help into the earthquake region
Loss of life
Buildings often collapse or are destroyed
When was the Caledonian period of folding and give an example
400m years ago
Blue stack mountains
What occurs at conservative boundaries
Plates slide pass each other, earthquakes
Explain continental drift
Movement of plates
Give two positives of volcanoes
Soils made from lava are rich in minerals. Suitable for agriculture
Hot springs or geysers form, used to heat people home with geothermal energy
Give two negatives of volcanoes
Lava burns everything in its path, loss of life
Poisonous gases, sulpher dioxide and can cause acid rain
