L10&11 - Volcanoes Flashcards
1
Q
Define a volcano
A
A vent at the Earth’s surface through which magma (molten rock) and associated gases erupt, and also the cone built by effusive and explosive eruptions.
2
Q
Describe the formation of a volcano as a 3 stage process.
A
1 - Magma from asthenosphere rises to form crustal magma chamber
2 - Lava erupts from central vent and side vents
3 - Accumulates to form volcano
3
Q
What are the 4 main components of magma?
A
Liquid portion - melt
Solid portion - crystallised minerals
Solid rocks - xenoliths
Dissolved gases
4
Q
What are the 3 ways magma can form?
A
Heating rocks - Temp. higher with increasing depth
Reduction in confining pressure - Lowers melting point
Addition of volatiles - Lowers melting point
