Volcanos
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How much of the crust is volcanic?
90% of the top 16 km
What makes volcanoes good things to live near?
geothermal energy, form fertile soils
How do volcanos form fertile soils?
they bring nutrients from earth’s interior to the surface; add material to the surface that weathers easily, making fertile soil
When and where was the last major eruption?
1815; Tambora
What is magma?
molten rock
What is lava?
magma on the earth’s surface
What does plutonic mean?
intrusive - from the interior of the crust
What are the 3 components of magma?
solid, liquid, dissolved gases
What does volcanic mean?
extrusive - on the exterior of the crust
What types of material are erupted from a volcano?
lava (liquid), pyroclastics (solid), and volcanic gas
How does lava behave?
as a liquid
In what direction does lava flow?
downhill (usually in stream courses)
How thick are lava flows?
1 to 400 m (average ~ a few metres)
How long can lava flows be?
> 100 km
What can have a volume of 12.5 cubic km?
lava flows
At what velocities can lava flow?
2 to 45+ km/h
What factors control the size and shape of a lava flow?
viscosity, yield stress, topography, source geometry
What controls viscosity of a lava flow?
compositoin
What does viscosity of a lava flow control?
speed
How does yield stress relate to lava flows?
lava flow stops when eruption stops - need to be adding lava for it to keep moving
What are 2 types of lava flow sources?
point sources and line sources (fissure)
What are pyroclastics?
solid debris erupted by a volcano
What happens to pyroclastics upon eruption?
transported and deposited by wind and water
What are the 5 types of pyroclastic particles, from smallest to largest?
dust, ash, lapilli, bomb, block