volcanoes Flashcards
What is a volcano?
A rupture in the crust of the Earth,
allows hot lava, volcanic ash and gasses to escape
from a magma chamber below the surface
Why do volcanoes occur?
Earth crust is broken into 17 tectonic plates that float on a hotter softer layer in the mantle
Name 4 hazards a volcano can cause
- volcanic ash threat to aircraft, ash particles damage the turbine
- large eruptions affect temp when ash obscures the sun and cools the Earth lower atmosphere or troposphere
- ash cloud absorb heat from Earth - warming the stratosphere
- Eruptions can cause volcanic winters which cause famines
Name the different types of volcanoes (6)
LQ
- Shield volcanoes
- Lava domes
- Volcanic cones/cinder cones
- Stratovolcanoes
- Super volcanoes
Explain shield volcanoes (7)
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SHIELD VOLCANO:
- broad, shield like profiles
- Lawa flow great distance from vent
- do not explode
- more common in ocean than on continent
- Hawaiian volcanic chain are shield volcanoes
- also occur in Iceland
Explain Lava Domes (5)
LQ
LAVA DOMES:
- formed by slow eruptions of lava
- sometimes formed within crater of previous volcano
- produce violent,explosive eruptions
- Lava doesn’t flow far from vent
Explain volcanic cones/cinder cones (5 )
LQ
VOLCANIC CONES / CINDER CONES:
- Eruptions of small pieces of land that build up around vent
- Short lived eruptions
- Produce cone shaped hill
- Cinder cones erupt only once
- Form flank vents on larger volcanos
Explain Stratovolcanoes (8 )
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STRATOVOLCANOES:
- tall mountains of lava flows
- made of cinder, ash, lava
- cinder and ash pile on each other lava flows over the cinder/ash where it cools and hardens, process is repeated
- Ash of eruption is biggest threat to human
- Preasure builds up from underlying lava, giving the most powerfull eruptions.
- Steep slopes of 30 - 35*
- shoots loose material = volcanic bombs
- big bombs measure 1.2 m across and weigh several tons
Explain Super Volcanoes (4)
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SUPER VOLCANOES:
- Great defastation
- Because of large area covered it cause cooling of global temp for many yrs
- Sulphar and ash into atmosphere blocks sun
- Most dangerous type of volcano
Name the 3 classifications of volcanos
and discuss each with 2-3 points
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1. Active:
- Lifespan is from months to several million yrs
- Scientist consider a volcano active if it has erupted the past 10 000 yrs
- Most active volcanos is Pacific Ring of Fire
2. Extinct:
- Volcano cannot erupt because there is no more magma
- If there is no written records of the activity it is considered extinct.
3. Dormant:
- Difficult to seperate extinct and dormant.
- Yellowstone has a dormant period of 700 000 yrs
- Climate change can trigger volcano activity as well as changing pressure of ice or sea water
- or extreme weather can trigger activity
Discuss the Effects of Volcanoes
5
LQ
1. Volcanic Gasses:
- Volcanoes Concentrations differ but
- Water Vapour is the most common
- followed by carbon & sulphur dioxide
2. Acid Rain:
- Gasses like carbon dioxide, hydrogen Chloride and hydrogen Fluride are released into atmosphere when volcano erupt
- Gasses disolve in water droplets in eruption cloud
- Fall back to ground in acid rain
3. Advantages of volcanoes:
- Put nutrients back into soil when volcano rocks weather
- is good for plants and crops
- Can form new islands when magma cools and solidifies when in contact with water
4. Volcanic Winters:
- Took place 70 000 yrs ago in Indonesia.
- Formed the Siberian Traps, most well known Volcanic area
- Freezing winter in Europe in 1740 - 1741 led to wide spread famine
5. Climate Change:
- 1815 Mount Tambora erupted causing global climate change in Northern Hemisphere.
- Crops didn’t grow and livestock died
