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Flashcards in Volcanoes Deck (19)
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1
Q

Lava Types

A

Basaltic, andesitic and rhyolitic

2
Q

Basaltic Lava

A
  • 50% silica content
  • Low viscosity
  • Associated with gentle eruptions (lava flows)
    (fissure, shield)
3
Q

Andesitic

A
  • 60% silica content
  • Medium viscosity
  • Associated with intermediate eruptions
  • Lava flows and ash
4
Q

Rhyolitic

A
  • 70% silica content
  • Doesn’t travel far from vent
  • Violent eruptions/directed blast
  • Pyroclastic flows
5
Q

Fissure/Icelandic

A
  • Low profile
  • Fissure/fracture
  • Basaltic lava
  • Divergent plate boundaries
  • Many kilometer’s long
  • “Curtain” lava
  • Gentle eruptions
6
Q

Shield/Hawaiian

A
  • Low profile/dome shape
  • Crustal rock is bent upwards due to magma chambers
  • Basaltic lava (Gentle Eruptions)
  • Mostly lava flows (“boil over”)
  • Lava runs far from vent in thin layers
7
Q

Difference between Magma and Lava

A

Magma is below the ground, lava is above

8
Q

Dome/Acid

A
  • High profile due to andesitic and rhyolitic
  • Lava cools mostly in vent due to high viscosity
  • Thick lava associated with “acid lava”
  • Intermediate eruptions (ash and pyroclastic)
9
Q

Ash/Cinder

A
  • High profile to a 45 degree max
  • Composed of individual ash particles from past eruptions
  • Lava escapes through lava tubes at base
  • Intermediate eruptions produce ash which escapes through vents
10
Q

Composite/Strata

A
  • Classic style
  • Alternate layers of ash and lava
  • Rhyolitic lava creates violent eruptions
  • Pyroclastic flows, nuvee ardents, ash and directed blasts
  • High viscosity means much magma solidifies in the vent creating more pressure. = bigger explosion
11
Q

Caldera

A
  • Skeleton of past composite volcano. Violent eruption caused magma chamber to empty and sink.
  • Still existing convection currents mean young volcanoes can form within the creator
  • If an island previously, sea water can flood the creator
  • Rhyolitic lava
12
Q

Icelandic Eruption

A

Lava flows gently from fissure

13
Q

Hawaiian Eruption

A

Lava is admitted gently from the vent

14
Q

Strombolian Eruption

A

Small but frequent eruptions occur

15
Q

Vulcanian Eruption

A

More violent but less frequent eruptions

16
Q

Vesuvian Eruption

A

Violent explosion after a long period of inactivity

17
Q

Krakatoan Eruption

A

Exceptionally violent that may remove much of the original core

18
Q

Peléan Eruption

A

Violent eruption accompanied by pyroclastic flows that may include a growing cloud

19
Q

Plinian Eruption

A

Large amounts of lava and pyroclastic material are ejected