MrMcMahon Learning Objectives To understand WHY volcanic activity occurs To understand HOW the distribution of Volcanic activity relates to plate boundaries To EXPLAIN how Volcanic activity can be predicted ID: 439591
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Slide1
Unit 1.3 : Volcanic Activity
Mr.McMahon Slide2
Learning Objectives To understand WHY volcanic activity occurs.
To understand HOW the distribution of Volcanic activity relates to plate boundaries.To EXPLAIN how Volcanic activity can be predicted.
To be able to identify different types of volcano and name its parts
To understand the impact that volcanic activity has had on the Irish landscape
To study how
geothermal energy
can be harnessed.
To understand the effects that Volcanoes have on people. Slide3
Why do Volcanoes Erupt ?Ans – Pressure Molten Magma
is less dense than hard rock. It is capable of flow. Gasses held under high pressure in a magma chamber
force the magma to the surface through vents.
Vents
develop along
fault lines, hotspots
,
ridges and trenches.
Mount Pinatubo eruption
as seen from space
http://www.youtube.com/watch?v=jRfEGvp6wDUSlide4
What is a Volcano ?A volcano is a opening in the earths crust through which molten material from the interior can make its way to the surface.Volcanoes form along plate boundaries
where rock is recycled.The distribution of the worlds volcanoes can be explained by studying the worlds plate boundaries. Slide5
Global distribution of Volcanoes
http://www.youtube.com/watch?v=JfHBCYTzuckSlide6
Global DistributionThe global distribution of volcanoes can be explained by their location in relation to fault lines.Volcanoes are found on convergent, divergent and transform boundaries.Slide7
Destructive BoundariesWhen subduction occurs as plates collide the descending old crust is melted in the asthenosphere. The melted rock rises through the crust through a vent. This creates central vent eruptions along chains of fold
mountain's.E.g. The Andes, South America
A Slide8
Divergent BoundariesAt Divergent Boundaries new crust is created. As the plates pull apart the sea floor spreads and magma rises to fill the void.This results in the creation of new crust and ocean ridges which rise to form islands.Iceland and the Mid-Atlantic RidgeSlide9
Cycle of Volcanic ActivityActive (Live): Erupts on a Regular basis.
Dormant (live): Volcanoes that have not erupted in recent recorded history. Can be asleep from 100-600 years.Extinct (dead) Has not erupted since historical times. There is no lava supply.Slide10
Volcanoes In Europe
Eurasian Plate
African PlateSlide11
Volcanic MaterialMagma – Molten material inside the earth. Lava
– over 1000 C. Low in silica so it is less viscous and runny. Acidic Lava : Contains gas bubbles that cannot escape easily and so explodes with force.
http://www.youtube.com/watch?v=ePra9ycif7MSlide12
Pyroclastic MaterialThis is the material ejected by a volcano. It includes ash, cinders, Pebbles and rock –Volcanic bombs and pumice.Lahars : Devastating mudflows that result when volcanic material mixes with snow melt water or heavy rainfall
http://www.youtube.com/watch?v=yvG_N7eqMWk&feature=relatedSlide13
Volcanic GassesSteamCarbon MonoxideChlorine
HydrogenSulphurous Oxides. Depending on the type of lava explosions can be devastating. Acid Rain can result when the gasses react with moisture in the atmosphere.Slide14
Volcanic Landforms Volcanic landforms fall into two main categories.Intrusive : Formed inside the earth.
Extrusive formed on the surface.Slide15
Extrusive : Central Vent EruptionForm at destructive boundaries.As lava and other material builds up on the surface it creates a volcanic cone.Slide16
Anatomy of a Central Vent Eruption
Magma Chamber Vent
Crater
Secondary Flow
Cloud of Pyroclastic Material
Pipe
Alternate Layers
Of Ash and Lava
Lava FlowSlide17
Types of Central Vent EruptionsComposite Volcano
: Layers of alternate ash and lava.Lava Dome: Thick viscous lava that solidifies to form a dome over a vent.
Caldera.
A large surface crater where a cone collapses in as it was consumed by the Magma chamber below it.
1
2
3Slide18
Fissure Eruptions Fissures are cracks caused by plate movement . Krafla : This is a 20KM long fissure in Iceland that has been erupting for over 30 years spewing lava.
The Derry Antrim Plateau formed from fissure eruptions 65 million years ago.Slide19
Hot SpotsHot Spots are places where volcanic activity takes place far in from plate margins. They from where there is often a thin crust overlying a hot mantle.A plume of magma rises from the mantle and melts a spot in the crust through which lava escapes.
E.g. The Hawaiian Islands.Slide20
Intrusive Landforms Landforms of volcanic activity that are created beneath the surface. Magma cools slowly inside the crust to create intrusive igneous rock e.g. Granite.
Plutons is the collective name for intrusive landforms.
http://www.youtube.com/watch?v=A5LdZJiKsVkSlide21
Intrusive Landform's … cont’d Batholiths: The Largest of the Plutons. Coarse with large crystals. They are exposed after denudation wears away the crust above them.E.g. Leinster Batholith Dublin, Wicklow Mountains.Slide22
LaccolithsDome like structures of hard intrusive igneous rock that bulged upwards against the overlying rock strata.Slide23
Sills Horizontal sheets of igneous rock that run parallel to the under and overlying rock strata.They formed when magma forced its way into the bedding planes of sedimentary rock where it cooled and solidified.Slide24
Dykes.Vertical sheets of volcanic rock that cooled and solidified in vertical cracks in the crust. Slide25
Plutonic Landforms Slide26
Human interaction
with VolcanoesSlide27
Predicting Volcanic ActivityIncrease in sulphur and carbon levels in soils on or close to volcanic slopes.Increase in the temperatures of groundwater.Changes in the shape of the volcano as magma upwells within.Some volcanic activity may be preceded by plumes of smoke, ash and steam.
Magma heating rock in the upper mantle may cause small tremors.
Measuring Gas samples Slide28
Beneficial effects of VolcanoesThe creation of fertile soils. Ash and cinders are natural fertilisers. Cash crops such as tea, coffee, cotton and coco are grown in volcanic soils.Tourist Attractions: Yellowstone National Park, USA and Mt. Etna , Sicily.
http://www.youtube.com/watch?v=bVYD2gtq4IASlide29
Geothermal Activity: A renewable source of energy whereby the heat of volcanically heated springs are harnessed to provided clean green energy. E.g. Iceland.Slide30
Case
Study :
Mount St. Helen’s
1980Slide31
Before and after
http://www.youtube.com/watch?v=UK--hvgP2uYSlide32Slide33
Mount St Helen’s Fallout.Slide34
Volcanic Activity In IrelandAs we have studied Ireland moved from 60 south of the equator to its present positionThe Derry –Antrim PlateauThe Leinster Batholith
Slemish MountainSlide35
The Derry-Antrim PlateauFormed by basalt- an extrusive igneous rock that cooled slowly on the surface.Covers 4,000km2 rising to 350m in height. When the lava cooled 60 million years ago it covered over the original chalk seafloor.Slide36
The Giants Causeway on the Antrim coast is but a part of the Derry-Antrim Plateau. To understand how the structure was formed we can look at Iceland today. When the Eurasian –American plates pulled apart 60 million MYA the crust thinned and magma cooled slowlySlide37
The Leinster BatholithA batholith is a Pluton- an intrusive igneous formation that formed slowly inside the crust.Large crystals had time then to form in granite.The Leinster batholith stretches south west over a distance of 120 km.
A
B
C
DSlide38
Geothermal Energy in IcelandGeothermal energy is a form of renewable energy derived from heat deep in the earth's crust. Geothermal Energy has been around for as long as the Earth has existed. "Geo"
means earth, and "thermal" means heat. So, geothermal means earth-heat. Slide39
Geothermal power is generated in over 20 countries around the world including Iceland, the United States, Italy, France, Lithuania, New Zealand, Mexico, Nicaragua, Costa Rica, Russia, the Philippines, Indonesia, the People's Republic of China and Japan. Slide40
Iceland Iceland –The land of Ice and Fire.307,000 Population.Lowest Population Density in Europe.85 % of all houses and 30% of electricity in Iceland is produced by geothermal energy.
http://www.geoberg.de/en/2010/06/12/geothermal-energy-in-iceland/Slide41
How is Geothermal Energy used ?Domestic : Homes, swimming pools, public baths Industrial: Fishfarming-de icing holding pools, Kiln drying timber in saw mills, electricity production.
http://www.youtube.com/watch?v=kWN5yXCYeXcSlide42
How Geothermal Energy Works
http://www.youtube.com/watch?v=rfUQy86ZMpQSlide43
Key ConceptsVolcanoPyroclastic MaterialLava (Basis and Acidic)Magma
Active LiveDormant Live ExtinctIntrusiveExtrusiveCentral VentCaldera
Fissure
Hotspot
Lahar
Geyser
Cascadia
Pacific Ring of Fire
PlutonsLaccolithsBatholithsSillsDikes
PlateauGeothermal Energy