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what is volcano? Distribution of volcanoes, Hazards associated with volcanic eruptions Risk and benefits living near volcanoes

lynn ho

on 13 February 2013

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Transcript of Copy of VOLCANOES

photo credit Nasa / Goddard Space Flight Center / Reto Stöckli VOLCANOES VOLCANIC ERUPTION Where can volcanoes be found? STRUCTURE
FORMATION ash clouds SHAPE AND SIZE of volcanoes Dependent on the Characteristics of lava

(a) Viscosity of Lava flow
(c) Amount of gas trapped in the lava RISKS BENEFITS on PLANET EARTH what is a volcano? landform formed by magma ejected from the mantle onto the Earth’s surface VOLCANOES EMIT: Volcanic Gases Ash
molten rock (basalt and andesitic) Dust
the movement of volcanic materials like hot rock fragments and super heated gases ejected at great velocity downhill MAGMA Vulcanicity:
upward movement of the magma both into the Earth’s crust and onto the Earth's surface. molten rock found below
the Earth's surface What happen when MAGMA
reach the Earth' Surface? Lava flow out and hardens this process is called
Carbon dioxide
Hydrochoride acid
Sulfur dioxide extremely fine particles,
smaller than ash Convergent Plate
Boundaries Divergent Plate
Boundaries PLATE MARGINS where tectonic plates meet Regions of instability
Fractures are found most evidently along THE PACIFIC RING OF FIRE Large concentration of earthquakes and volcanic eruptions occur along the edges of the Pacific Ocean. ¾ of the earth’s 550 historically
active volcanoes The Pacific plate collides and slides underneath other plates Hotspot Volcanoes Localised rising plume of hot molten
magma from deep mantle
Result in non-explosive eruptions Hawaiian Islands are
example of Hotspot
volcanoes of volcano of living near volcanoes of living near volcano OVERVIEW: VOLCANO 101 Magma pushes it way out! through cracks found
on Earth's surface WHY ARE THERE CRACKS? Plate Tectonics
Plates are constantly moving due to
convection current in the mantle. FORMATION of Volcano plates moving towards each other Destructive plate movement crusts are destroyed Denser plates (oceanic) subducts under the less dense (continental) plate the crust of the subducted plate melts and generate Magma Magma rises through the vent and onto the Earth's surface as Lava Found in the middle of plate Constructive plate movement new crusts are formed Eyjafjallajokull, Iceland Divergent plate movement between North American Plate and Eurasian Plate Plates moving away from each other
Magma rises to Earth's surface Create new ocean floor &
submarine volcanoes Are all volcanoes only
found at plate
boundaries? Question: pyroclastic flow magma chamber main vent secondary vent secondary cone volcanic bombs lava flow crater Structure of a stratovolcano reservoir of molten rock beneath the earth’s crust opening in the earth’s surface with a pipe leading into the magma chamber summit of the volcanoe may be blown off during an explosive eruption Sides of the crater may collapse inwards Caldera Tambora, Indonesia Double craters- Kelimutu, Indonesia large volcanic depression Kilauea crater collapse Yellowstone Caldera, USA Taal, Philippine
small, 3km wide caldera Mt Pinatubo in Philippines VISCOSITY BASIC LAVA ACIDIC LAVA Low silica content
Highly fluid and flow easily
High temperature (1100-1200 degree celsius)
Flow over long distance then solidifies low viscosity refer to the resistance to flow high viscosity Produce at Destructive Plate boundary
High Silica content (thick and sticky)
Flow slowly, cools and solidify quickly subduction process SHIELD VOLCANO NATURE OF LAVA FLOW Strength of eruption STRATOVOLCANO Nature of Lava Flow Strength of Eruptions composite volcano High Viscosity magma trapped gas Prevent gas bubbles from escaping Build up pressure within the magma as it rises to the Earth's surface Explosive eruption Imagine this Pour water into a glass
You will see:
Air bubbles expands as there rises towards the surface Mauna Loa, Hawaii Mt Washington, USA Belknap Mt Wrangell in Alaska gentle sloping sides The summit of La Cumbre, a shield volcano on Fernandina Island, Galapagos Islands, as seen from Earth orbit Broad summit Hot and fluid
Low viscosity magma
Spread over a wide area, cools and solidify slowly Frequent eruptions but usually quiet and gentle with large quantities of fluid basic lava Mt Mayon, Philippines Mt St Helen's Aerial view Popocatepetl in Mexico slight concave profile Steeper slope at the top gentler slope at the base Viscous acidic lava, ash and rock fragment
High viscosity magma
Flow less readily over a smaller distance then solidifies Violent explosive eruptions

Lateral eruptions-lava may escape from the sides of the cone. FINDING OUT THE RISKS AND BENEFITS GROUPWORK TIME! "mountain of fire' -most dangerous volcano in Indonesia
Active: erupting regularly (about once in ten years)
Close proximity to it is the city of Yogyakarta L E A R N I N G O U T C O M E S What is a volcano?
Structures and formation of volcano
Types and shapes of volcanoes
Risk and benefits of living in volcanic areas You will know: of living at volcanic areas Form into groups of 5/6 Summarize the risks and benefits of living near volcanic areas Each groups to do 2 min presentation of one risk/benefit of living near volcanic areas RESEARCH! presentation:
or any other creative ways Eruption of Mt Merapi in Indonesia VOLCANOES ARE DANGEOUS ! BUT... Why are there settlement found near volcanic regions? PRECIOUS STONES, MINERALS AND BUILDING MATERIALS TOURISM GEOTHERMAL ENERGY Population growth?
Good Soil for agriculture?
Capitalise for energy generation?
Valuable materials/rocks? DESTRUCTION BY VOLCANIC MATERIALS LANDSLIDE POLLUTION EFFECT ON WEATHER DORMANT Volcano ACTIVE Volcano EXTINCT Volcanoes TYPES OF VOLCANOES based on frequency of eruptions Constant emission of lava, ash and rock fragments
Strong sulphur smell
Less violent volcanic eruptions Currently inactive but may erupt in the near future No current seismic activity and no geological evidence of eruptions in recorded history Measuring Strength of Volcanic Eruptions Volcanic Explosivity Index VEI Hazards to aircraft delayed flights Damaged Engine Poor visibility Ash particles Ruins of Pompeii Bury houses and building roof collapse Respiratory Problems Volcanic Gases Toxic & Poisonous formation of acid rain Global cooling Sulfur based particles
reflect sunlight Mt Tambora, 1815 1.7˚C dropped in mean global temperature Displacement of land and rocks as a result of ground movement Flooding
Damaged transport routes, houses Lava Flow Pyroclastic Flow Volcanic bombs of heated rock Ash clouds + WATER (MUDFLOW) LAHAR incinerate everything in its path especially basic lava Traditional sulfur miners at acidic active volcano RISK to make matches, fertilisers and
bleach sugar Geothermal Power Station in Iceland Harnessing heat energy from the Earth's crust In Reykjavik, Iceland, homes are heated using geothermal energy FERTILE VOLCANIC SOILS Java and Bali, Indonesia Rich in Potassium, Phosphorus
Act as Natural Fertiliser Favorable for Agriculture scenic landscape Tourist destination Brings in $$ Yellowstone National Park, Wyoming Old Faithful Geyser in MONTSERRAT’S SOUFRIERE HILLS VOLCANO PYROCLASTIC FLOW LAVA FLOW Carbon dioxide (Greenhouse gas) Trap heat in the atmosphere Effect by: CO2 << S plate boundaries constantly experience tremendous pressure San Andreas Fault The ruin of Pompeii after the eruption of Vesuvius in AD79 Yellowstone Supervolcano
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