Volcanic Activity Flashcards
Subduction Convergant plate boundaries
Collision, heavier subducts, explosive eruption (not diarrhea), Reaches surface, volcanic arc formed, Island arc
Constructive plate boundaries
Magma rises through fissure, cools on contact with ocean water, forms mid ocean ridge , mountains, less explosive eruptions runny lava 💩
Hotspots 😉
Hotter regions of the mantle, located at fixed point while the plates moves over it, plumes of magma rise and break through forming a volcano, over time the volcano becomes extinct and a new one forms further aside, islands form, e.g Hawaii
Basic Volcano features
- Low silica content (50%)
- 1,100 ° C
- Travel long distances
- Cools and hardens slowly
- Quiet eruptions
Acidic Volcano
- High Silica content (70%)
- 900°C
- Thick so travels short distances
- Cool and hardens quickly
- Violent eruptions
Shield Volcanoes
E.g Mauna Loa, Hawaii
-Largest on earth
-Gradual slopes
-Formed basic lava flows
-Usually at divergent boundaries or hotspots
Composite Volcanoes
E.g Mt Fuji
- Steep sided conical shaped
- Alternate layers of acidic lava, tephra, ash
- Convergent, destructive
- Acidic lava
Caldera
E.g Yellowstone
-Large depression (same), sunken volcano
-Violent eruptions, magma chamber collapses into an empty one
Fissure eruptions
E.g Antrim Plateau
- Basic lava quietly from linear crack
- Lava spreads slowly over a large area
- Can form lava plateau
Hydrothermal vents/Geysers
E.g Old Faithful, Yellowstone
-Springs that eject hot water with great force
- Water at lower crust is heated by surrounding hot rock,
- pressure builds up and eventually a spray of hot cum…oh oops I mean water…. and steam explode into the surface
Black smokers
E.g Mid Atlantic Ridge
- Chimney like vents
- found 3,000m below near mid ocean ridges
- superheated water contains particles of minerals such as sulphur
Intrusive ‘plutonic’ features
Plutons, Conduits, Laccolith, pasilade, batholith, sill, dikes
