Volcanoes Volcanoes are are
Hot StuffHot StuffByBy
Shana Huffaker And Doreen SnyderShana Huffaker And Doreen Snyder
Modified by Mr. KennedyModified by Mr. Kennedy
What is a Volcano?What is a Volcano?
• Volcano- Areas of earth’s surface through which magma and volcanic gases pass
• Volcano comes from the Roman word Vulcan, which means “fire”
Magma rises because it is less dense than the solid rock around it.
What are the parts of a What are the parts of a Volcano?Volcano?
1. VENT- the vent is the opening from which lava flows. Dust, ash, and rock particles can also be thrown out of the vent!
A lava flowlava flow is the area covered by lava as it pours out of a vent
A cratercrater is a bowl-shaped area that may form at the top of a volcano around the central vent
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)
How are How are volcanoes volcanoes formed?formed?
Deep in the earth it is very hot. It is so hot that rocks melt. The melted rock is called
magma. The magma is lighter
than the rocks around it so it rises. Sometimes it finds a crack or hole in the earth’s crust and
bursts through. This is how a volcano
begins.
Why do Why do volcanoes volcanoes
erupt?erupt?
Pressure builds deep in Pressure builds deep in the earth where the the earth where the
magma is. Suddenly the magma is. Suddenly the gases escape and gases escape and
violently explode. It is violently explode. It is kind of like toothpaste kind of like toothpaste squirting out of a tube squirting out of a tube when you give it a hard when you give it a hard
squeeze.squeeze.
What are the What are the different kinds of different kinds of
volcanoes?volcanoes?
Volcanoes do not all look Volcanoes do not all look alike. Their shape is alike. Their shape is
based on what type of based on what type of materials they erupt. materials they erupt. There are three main There are three main kinds, or shapes, of kinds, or shapes, of
volcanoesvolcanoes. .
3. Volcanic cone- is the pile of lava, dust, ashes, and rock around the vent. It can be found in different shapes!
Types of Volcanoes
Shield volcano
Cinder cone volcano
Composite volcano
ShieldShieldVolcanoesVolcanoes
Volcanoes that build up Volcanoes that build up from from
many slow, steady, many slow, steady, flows of hot lava, are flows of hot lava, are
called shield volcanoes. called shield volcanoes. This kind of volcano is This kind of volcano is
low and broad with low and broad with gently sloping sides. gently sloping sides.
They look like a They look like a warriors shield.warriors shield.
Shield VolcanoShield Volcano
• Is wide and somewhat flat.
• It forms from a quiet eruption.
• Lava flows out quietly and for great distances.
Cinder Cone Cinder Cone VolcanoesVolcanoes
Cinder cone volcanoes Cinder cone volcanoes form when solid rock form when solid rock and ash shoot up into and ash shoot up into the air and fall back the air and fall back around the volcano around the volcano
opening. The cinder opening. The cinder cone volcano has cone volcano has
steeply sloped sides.steeply sloped sides.
Cinder Cone VolcanoCinder Cone VolcanoHas tall, very steep sides.
Has explosive eruptions.
This eruption produces a lot of cinder and ash.
Strato Strato or Composite or Composite
VolcanoesVolcanoes
Strato volcanoes, also Strato volcanoes, also called composite called composite
volcanoes, erupt with volcanoes, erupt with molten lava, solid rock, molten lava, solid rock,
and ash. The layers and ash. The layers pile up much like layers pile up much like layers of cake and frosting. of cake and frosting. The layers form into The layers form into
symmetrical cones, and symmetrical cones, and the slopes are steep.the slopes are steep.
Composite VolcanoComposite Volcano
Form from explosive eruptions.
Produce a lot of lava and ash.
Is small, with steep sides.
What’s inside a volcano?What’s inside a volcano?
• Magma Chamber- molten rock that feeds a volcano
• Vents- cracks in the crust
• What is the difference between magma and lava?
Types of VolcanoesTypes of Volcanoes
• Shield Volcano
a) Built from layers of lava
b) Non-explosive eruptions
c) Not very steep, but can be big
Types of VolcanoesTypes of Volcanoes
• Cinder Cone Volcano
a) Built from pyroclastic material
b) Moderately explosive, short eruptions
c) Small in size, steep slopes
Types of VolcanoesTypes of Volcanoes
• Composite Volcanoes
a) Most common type
b) Explosive eruptions and lava flow
c) Built from pyroclastic material AND lava
What Erupts from a Volcano?
Lava can be thick or thin.
Blocky lava
PahoehoeAa
Pillow lava
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
Volcanic blocks
Volcanic bombs
Lapilli
Volcanic ash
• 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
How do volcanologists predict How do volcanologists predict eruptions?eruptions?
There is much more about There is much more about volcanoes out there. Look volcanoes out there. Look
in books and on the in books and on the internet . Have Fun!internet . Have Fun!
Pictures, Images, and information From:Soames Summerhays/Photo Researchers, Inc.
Kraft-Explorer/Photo Researchers Inc.Masao Hayashi-Dung/Photo Researchers Inc.
Why Do Volcanoes Blow Their Tops? By Melvin and Gilda Berger
www.usgs.gov/education/learnweb/volcano/index.html