vent or 'chimney' that connects molten rock (magma) from
within the Earth’s crust to the Earth's surface.The volcano includes the surrounding cone of erupted material.
vent
cone
magma chamber
conduit
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Презентация на тему Volcanoes: Eruptions and Hazards
Содержание
- 2. What is a volcano? A volcano is
- 3. What causes volcanoes?The Formation of Magma Mantle
- 4. What causes volcanoes?Where Volcanoes Form Tectonic Plate Boundaries!!!~75% world’s active volcanoes in Ring of Fire
- 5. PlatesEarthquakesVolcanoesVolcanoes and Earthquakes are found on places where plates meet
- 6. What causes volcanoes?
- 7. What causes volcanoes?Hot Spots
- 8. How and why do volcanoes erupt?Hot, molten
- 9. Large amounts of gas and a high
- 10. The Composition of Magma Determines whether it
- 11. Pyroclastic material Rock fragments created by
- 12. What Erupts from a Volcano?Lava can be thick or thin.Blocky lavaPahoehoeAaPillow lava
- 13. How do volcanoes affect the Earth?Flows and
- 14. Types of VolcanoesShield volcanoCinder cone volcanoComposite volcano
- 15. Craters, Calderas, and Lava PlateauCrater From explosions
- 16. Explosive EruptionsMt. RedoubtExplosive volcanic eruptions can be
- 17. Three products from an explosive eruptionAsh fallPyroclastic
- 18. Direct measurements of pyroclastic flows are extremely dangerous!!!
- 19. Effusive EruptionsEffusive eruptions are characterised by outpourings of lava on to the ground.HawaiiCourtesy of www.swisseduc.ch
- 20. Pyroclastic flowLahars/Mud flowsPyroclastic fallLava flowNoxious GasEarthquakesVolcanic HazardsCourtesy of www.swisseduc.ch
- 21. Pyroclastic FlowFor example, eruption of Vesuvius in 79 AD destroyed the city of Pompeii
- 22. Pompeii (79AD) On August 24, 79AD Mount Vesuvius
- 23. Pompeii (79AD) Pyroclastic flows of poisonous gas and
- 24. Pompeii (79AD) The cities remained buried and undiscovered
- 25. How do pyroclastic flows cause devastation?
- 26. Pyroclastic Flow - laharsHot volcanic activity can
- 27. Pyroclastic FallAsh loadCollapses roofsBrings down power linesKills plantsContaminates water suppliesRespiratory hazard for humans and animals
- 28. Lava FlowIt is not just explosive volcanic
- 29. Volcano MonitoringVolcano Observatories are set up on
- 30. SeismicityDeformationGas Output (on volcano and remote sensing
- 31. Gas samples are collected from fumaroles
- 32. Скачать презентацию
- 33. Похожие презентации
What is a volcano? A volcano is a vent or 'chimney' that connects molten rock (magma) from within the Earth’s crust to the Earth's surface. The volcano includes the surrounding cone of erupted material. ventconemagma chamberconduit
Слайд 2
What is a volcano?
A volcano is a
The volcano includes the surrounding cone of erupted material.
Слайд 3
What causes volcanoes?
The Formation of Magma
Mantle rock
melts when the temperature increases
or the pressure decreases.
Слайд 4
What causes volcanoes?
Where Volcanoes Form
Tectonic Plate Boundaries!!!
~75%
world’s active volcanoes in Ring of Fire
Слайд 8
How and why do volcanoes erupt?
Hot, molten rock
(magma) is buoyant (has a lower density than the
surrounding rocks) and will rise up through the crust to erupt on the surface.Same principle as hot air rising, e.g. how a hot air balloon works
When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of gas (H2O, CO2, S) it has in it as to how it erupts.
Слайд 9 Large amounts of gas and a high viscosity
(sticky) magma will form an explosive eruption!
Think about shaking
a carbonated drink and then releasing the cap.Small amounts of gas and (or) low viscosity (runny) magma will form an effusive eruption
Where the magma just trickles out of the volcano (lava flow).
How and why do volcanoes erupt?
Слайд 10 The Composition of Magma Determines whether it is
explosive or not!
High
contentMore 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
water
silica
EXPLOSIVE
EXPLOSIVE
Слайд 11
Pyroclastic material
Rock fragments created by
eruptions
magma explodes from volcano and solidifies in
the airexisting rock is shattered by powerful eruptions
Volcanic blocks
Volcanic bombs
Lapilli
Volcanic ash
EXPLOSIVE
What Erupts from a Volcano?
Слайд 13
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
Слайд 15
Craters, Calderas, and Lava Plateau
Crater
From explosions of
material out of the vent and the collapse of
material back into ventCaldera
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)
Слайд 16
Explosive Eruptions
Mt. Redoubt
Explosive volcanic eruptions can be catastrophic
Erupt
10’s-1000’s km3 of magma
Send ash clouds >25 km into
the stratosphereHave severe environmental and climatic effects
Hazardous!!!
Above: Large eruption column and ash cloud from an explosive eruption at Mt Redoubt, Alaska
Слайд 17
Three products from an explosive eruption
Ash fall
Pyroclastic flow
Pyroclastic
surge
Explosive Eruptions
Pyroclastic flows on Montserrat, buried the capital city.
Слайд 19
Effusive Eruptions
Effusive eruptions are characterised by outpourings of
lava on to the ground.
Hawaii
Courtesy of www.swisseduc.ch
Слайд 20
Pyroclastic flow
Lahars/Mud flows
Pyroclastic fall
Lava flow
Noxious Gas
Earthquakes
Volcanic Hazards
Courtesy of
www.swisseduc.ch
Слайд 22
Pompeii (79AD)
On August 24, 79AD Mount Vesuvius literally
blew its top, erupting tonnes of molten ash, pumice
and sulfuric gas miles into the atmosphere. Pyroclastic flows flowed over the city of Pompeii and surrounding areas.
Слайд 23
Pompeii (79AD)
Pyroclastic flows of poisonous gas and hot
volcanic debris engulfed the cities of Pompeii, Herculaneum and
Stabiae suffocating the inhabitants and burying the buildings.
Слайд 24
Pompeii (79AD)
The cities remained buried and undiscovered for
almost 1700 years until excavation began in 1748. These
excavations continue today and provide insight into life during the Roman Empire.
Слайд 26
Pyroclastic Flow - lahars
Hot volcanic activity can melt
snow and ice
Melt water picks up rock and debris
Forms
fast flowing, high energy torrentsDestroys all in its path
Слайд 27
Pyroclastic Fall
Ash load
Collapses roofs
Brings down power lines
Kills plants
Contaminates
water supplies
Respiratory hazard for humans and animals
Слайд 28
Lava Flow
It is not just explosive volcanic activity
that can be hazardous. Effusive (lava) activity is also
dangerous.
Слайд 29
Volcano Monitoring
Volcano Observatories are set up on all
active volcanoes that threaten the human population. These are
designed to monitor and potentially to predict the eruptive behaviour of the volcano in question.
Слайд 30
Seismicity
Deformation
Gas Output
(on volcano and remote sensing techniques)
These
three things are the most important precursors to an
eruption.Volcano Monitoring
Слайд 31 Gas samples are collected from fumaroles and
active vents.
Gas levels may also be monitored
by remote sensing techniquesGas Monitoring
