earthquakes and volcanoes - Coggle Diagram
earthquakes and volcanoes
Plate margins :volcano:
When two tectonic plates move parallel to each other
earthquakes are common as pressure builds between the two plates.
volcanoes are not formed since the plates are not moving into or away from each other
Examples include the San Andresa fault line in California
When two tectonic plates move into each otehr.
If two continental plates move towards each other, they are both buoyant and they form mountains since neither can sink under the other.
If an oceanic and continental plate move towards each other then the denser oceanic plate is subducted under the lighter continental plate. As the oceanic plate sinks it melts, this produces an increase in pressure under the plates causing the formation of earthquakes, fold mountains and volcanoes.
examples include Japan and the Philippines
When two tectonic plates move away from each other
As the two plates move away from each other the magma exposed to the surface cools and increases the size of the plate. As the new rock moves it often fractures causing earthquakes.
volcanoes are also formed as magma pushes up rock forming ridge and rift features. The lava produced in the volcanoes is runny
Examples include the Mid Atlantic Ridge found in Iceland
Living in hazardous areas
Energy production (geothermal)
Family friends and tradition
The earth's structure and plate tectonics
The crust is the outermost layer of the earths 's structure it is a thin layer of solid rock which is up to 60km thick. The earth's crust is broken into plates. Continental and oceanic plates.
The mantle of the earth is the thinkest layer found under the crust. the mantle contains semi molten rock called magma
The outer core surrounds the inner core, it is a liquid layer made from iron and nickel
The inner core is the innermost section of the earth, it contains solid iron and nickel and has temparatures of up to 5500C.
The theory of plate tectonics
The crust of hte earth is split into tectonic plates which are either oceanic or continental, the movement of the plates causes natural disasters such as volcanoes and earthquakes.
It is thought that the movement of the plates is caused by slab pull, this happens when denser plates sink into the mantle causing newer sections of the plate to be dragged along behind.
Types of volcano
Found on convergent plate boundaries where the oceaic crust subducts below the continental crust.
They product slow moving almost sticky lava
They have steep sides because the lava does not flow far betore solidifying
Alternate layers of lava and ash
Violent eruptions but less frequent.
Found on constructive plate boundaries where plates move away from each other
Runny lava and gentle sides becuase the laval travels further before solidifyng
less violent eruptions but more frequent
No layers (Volcano is only made from lava and no ash)
Effects and responses to volcanoes
Effects of earthquakes can vary depending on
Level of development
Magnitude of the earthquake
Depth of focus
Distance from epicentre
Time of day
Short term responses involve a short term response in the days and weeks after a disaster
Long term responses go on for years after the disaster and involve things such as rebuilding houses and kick starting the economy