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Volcanoes. Tungerahua Volcano, Ecuador Picture by Alcinoe Calahorrano. Volcanoes form around vents that release magma onto the Earth’s surface. Vents. Lava. Magma chamber. Volcanic Eruptions . Lava flow. Lava fountain. Nonexplosive Eruptions Explosive Eruptions. What is Lava ?

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volcanoes

Volcanoes

Tungerahua Volcano, Ecuador

Picture by Alcinoe Calahorrano

slide2

Volcanoes form around vents that release magma onto the Earth’s surface.

Vents

Lava

Magma chamber

slide3

Volcanic Eruptions

Lava flow

Lava fountain

  • Nonexplosive Eruptions
  • Explosive Eruptions

What is Lava?

-magma that flows onto the Earth’s surface

slide4

The Composition of Magma Determines whether it is explosive or not!

water

  • High water content
    • More likely to be !!!
  • High content
    • More likely to be !!!
    • Why?
      • Silica has a thick, stiff consistency
        • Flows slowly
        • Tends to Harden in the volcano’s vent

EXPLOSIVE

silica

EXPLOSIVE

slide5

What Erupts from a Volcano?

Blocky lava

Lava can be

thick or thin.

Pahoehoe

Aa

Pillow lava

slide6

What Erupts from a Volcano?

  • Pyroclastic material
  • Rock fragments created by eruptions
    • magma explodes from volcano and solidifies in the air
    • existing rock is shattered by powerful eruptions

EXPLOSIVE

Lapilli

Volcanic bombs

Volcanic blocks

Volcanic ash

slide7

How do volcanoes affect the Earth?

  • Flows and Fallouts
  • hot ash can flow really quickly
    • Knock down buildings
    • Dam rivers (flooding/drought)
    • Kill crops and livestock
  • Climatic Changes
    • Ash & Gases can block sunlight
    • Drop average global temperature noticeably
slide8

Types of Volcanoes

Shield volcano

Cinder cone volcano

Composite volcano

slide9

Craters, Calderas, and Lava Plateau

  • Crater
  • From explosions of material out of the vent and the collapse of material back into vent
  • Caldera
  • Much larger depression that forms when magma chamber empties and its roof collapses
  • Lava Plateau
  • Forms when lava erupts from long cracks, or fissures, and spreads out evenly (thousands of km)
slide10

What causes volcanoes?

  • The Formation of Magma
  • Mantle rock melts when the temperature increases
  • or the pressure decreases.
slide11

What causes volcanoes?

  • Where Volcanoes Form
  • Tectonic Plate Boundaries!!!

~75% world’s active volcanoes in Ring of Fire

how do volcanologists predict eruptions
How do volcanologists predict eruptions?
  • Measuring Small Quakes
    • Before eruption, increase in number & intensity
  • Measuring Slope
    • Bulges may form with magma (tiltmeter)
  • Measuring Volcanic Gases
    • Outflow of volcanic gases
      • Sulfur dioxide, carbon dioxide
  • Measuring Temperature from Orbit
    • Measure changes in temperature over time
you should not be a volcanologist if
You should not be a Volcanologist if….
  • You don’t like hiking, backbacking, rockclimbing, etc.
  • You are not interested in experiencing extreme temperatures and heights.
  • If you don’t like to travel to incredible places and see breathtaking views of the world.

Robert McGimsey

USGS

A. Ozerov