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Chapter 2 : Earthquakes & Volcanoes - Coggle Diagram
Chapter 2 : Earthquakes & Volcanoes
Tectonic processes affecting the magnitude of volcanic eruptions
Volcanic eruptions
When lava erupts onto the earth's surface from a volcano
It may form a cone-shaped mountain as more lava erupts & accumulates over time
Crater
Active vent
Magma chamber
Conduit
Main vent
Volcanic cone
Divergent plate boundaries
Plates move apart, crust stretches & fractures develop
The decrease in overlying pressure causes the underlying mantle to melt forming magma
Magma contains dissolved gases & is less dense than the surrounding materials
Magma rises through weak areas in the crust to the earth's surface to erupt as lava, causing a volcanic eruption
The lava cools, solidifies & accumulates over time, forming a volcano
Convergent plate boundaries
Plates move towards each other & the denser plates subducts under the other
As the subducting plates sinks into the mantle, the high pressure forces water out of the oceanic crust
Water lowers the melting point of the overlying mantle, causing it to melt, forming magma
Magma contains dissolved gases & is less dense than the surrounding materials
Magma rises through weak areas in the crust to the earth's surface to erupt as lava, causing a volcanic eruption
The lava cools, solidifies & accumulates over time, forming a volcano
Stratovolcano
Has more viscous magma
The dissolved gases in the magma cannot escape easily
More pressure builds up until gases escape explosively
Violent, explosive eruptions
Convergent
Magma (melted crust)
Higher VEI