SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Mauna Kea, - - PowerPoint PPT Presentation

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sio15 ss1 2020 lecture 9 volcanoes and plate tectonics
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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Mauna Kea, - - PowerPoint PPT Presentation

May 30, 2023 143 likes •387 views

SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Mauna Kea, Hawaii short video 7c Hawaii; Etna; Iceland; Erta Image: S. Marshak Earth, Portrait of a Planet Ale, Nyamuragira/Africa Mt. Mayon, Philippines Fuji; Vesuvius; St.

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

Hawaii; Etna; Iceland; Erta Ale, Nyamuragira/Africa Fuji; Vesuvius; St. Helens; Pinatubo; Popocatepetl

Image: S. Marshak “Earth, Portrait of a Planet” Mauna Kea, Hawaii

  • Mt. Mayon, Philippines

short video 7c

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

  • Mt. Mayon, Philippines

“...anything that looks beautiful is potentially dangerous...”

  • Mt. Fuji, Japan
  • Mt. St. Helens
  • Mt. Rainier
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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

effusive lava fountains small explosions large explosions; pyroclastic flows

short video 7c

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

  • Mt. St. Helens (May 18, 1980)

Arenal, Costa Rica Kilimanjaro Tanzania/Kenya (extinct) Kilauea, Hawaii (1983-87)

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

  • 90% of volcanism along plate boundaries

(with 80% along mid-ocean ridges)

  • 10% at intra-plate hotspots/rifts
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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

  • majority of volcanism

(80% of total magma production)

  • non-explosive eruptions

pillow lava black smokers

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

  • common
  • subduction zones
  • dangerous on continents
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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

  • relatively rare
  • rifts
  • some hotspots
  • Mt. Etna
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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

  • can be intra-plate
  • dangerous on continents
  • Yellowstone Earth’s worst!
  • places with lots of magma in mantle

(mantle plume)

  • overriding plate moves away ->

volcanoes go extinct -> chain

  • Hawaii most productive volcanoes

Loihi (youngest/active) Kauai (oldest/extinct)

Big Island (active) Maui Oahu

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

  • cont-cont collision
  • transform boundaries
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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

Lecture 2: resistance of material to flow

low viscosity: lava flows easily

  • > effusive volcanism

Image: S. Marshak “Earth, Portrait of a Planet”

high viscosity: lava clogs vents

  • > explosive volcanism

crustal rock more viscous than mantle rock!

short video 7c

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

OCEANIC CRUST

  • thin
  • dense, dark rock

Image: S. Marshak “Earth, Portrait of a Planet”

CONTINENTAL CRUST

  • thick
  • less dense, light rock
  • thicker crust
  • lighter rocks

higher viscosity

short video 7d

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

crustal thickness composition (SiO2 content) SiO2: silica CONTINENTAL CRUST HAS MORE SiO2 THAN OCEANIC CRUST

short video 7d

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

LESS VISCOUS low-SiO2 (Olivine) hot

Image: S. Marshak “Earth, Portrait of a Planet”

MORE VISCOUS high-SiO2 (Quartz) cold

1) MORE SiO2 makes lava MORE VISCOUS 2) HIGHER TEMPERATURE makes lava LESS VISCOUS

SiO2 = silica

short video 7d

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

geotherm Melting curve

Image: S. Marshak “Earth, Portrait of a Planet”

solid melt

short video 7e

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

solid melt

geotherm Melting curve

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

melt solid

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics Image: S. Marshak “Earth, Portrait of a Planet”

  • ven T:

260oC/500oF melting T or freezing point: 650 - 1100oC Quartz: 650ºC Olivine: 1100ºC yoF = xoC*9/5+32 1200 - 2000oF Magma/Lava mix of:

  • solid parts
  • molten parts
  • dissolved gases

minerals: Quartz (> SiO2) Olivine (<SiO2) partial melt: mix of solid and molten parts

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SIO15-SS1 2020: Lecture 9 Volcanoes and Plate Tectonics

  • melting solid rock: Quartz first to melt
  • solidifying hot melt: Quartz last to crystallize
  • > lava has more SIO2 than mantle rock left behind