Flashcards
volcanoes
Flashcards do conjunto (148)
- 1plate tectonicsa theory that attempts to explain the formation and distribution of the Earths major structural features in terms of a series of plates that make up its surface
- 2hot spota point on the surface of the earth located above a plume of rising magma. HAWAIIAN ISLANDS
- 3seismic wavesshock waves released by the rupture of rock strata at the focus of an earthquake. they travel through the rocks and are measured and recorded on a seismograph
- 4volcanoan opening or vent through which magma, molten rock ash or volatiles erupt on the surface of the earth
- 5solfataraan extrusive feature. small volcanic areas without cones, produced by gases mainly sulphurous escaping to the surface
BAY OF NAPLES IN ITALY - 6basaltic lavalow in silica
more fluid
allows gas bubbles to expand to the surface
low viscosity - 7batholithan intrusive feature, dome shaped
mass of igneous rock formed deep below the surface
forces overlying rock strata upwards - 8rift valleyconstructive plate margins
brittle crust fractures as it moves apart
area of the crust drop down to form parallel faults - 9subductiondenser oceanic plate is forced underneath the lighter continental plate
- 10lithospheresolid outer layer of the earth that consists of the crust and the rigid upper part of the mantle
- 11asthenosphereductile part of the earth
just below the lithosphere
layer of softer, almost plastic rock - 12continental crustcrust found under land
older
thicker
lighter than oceanic - 13oceanic crustcrust found under oceans
thinner
younger
much more dense than continental - 14geyserextrusive feature
water heated by volcanic activity
explodes onto the surface
YELLOWSTONE - 15palaeomagnetismthe study of the record of the earths magnetic field
certain minerals a line themselves with earths magnetic field
provides information on the past behavior - 16crustouter layer
thin layer
rocks rich in silican, oxygen, aluminium, potassium and sodium
5-70km thick - 17solid inner corehottest
solid made out of nickel and iron
temperatures 5500-6000
1,300km thick - 18liquid outer coreliquid, due to changes in pressure
made out of iron and nickel
hot temperatures
2000km thick - 19mantlewidest section
2,900km thick
made of semi molten rock: silcate, iron and nickel - 20mohorovijic discontinuityseparation between the crust and the upper mantle
- 21litospherecrust
upper part of the mantle - 22asthenospherelower semi-molten section of the mantle
-convection currents occur - 23continental plates-age:over 1500 million
-thickness: 30-70km
-composition:granite rocks rich in silican,aluminium
SIAL - 24oceanic plates-age:less than 200 million
-thickness:6-10km
-density: more dense
-composition: basalt rocks rich in silican, magnesium and oxygen
SIMA - 25evidence for Wegener's theory-geological evidence
-biological evidence
-climatological evidence
-jigsaw fit - 26geological evidence-evidence from glaciation during the late carboniferous period
-similar glacial deposits found in America, Antarctica and India
-rocks of the same age and type and display found in SE brazil and south Africa - 27biological evidence-similar fossil formations are found either side of the Atlantic (mesosaurus)
-the plant glossopteris is a fern that has been found in Africa, Australia and south america - 28climatological evidence-Antarctica, north america, svalbard and the uk contain coal deposits of similar age that were formed in tropical conditions
-no longer in tropical conditions - 29jigsaw fit-western seaboard of Africa and the eastern sea board of South America seem to fit together
- 30why was Wegeners theory not accepted-he was a meterologist
-couldnt explain sea floor spreading
-he was also german (cold war)
-already explanations accepted - 31when did wegener publish his theory theory basics1912
-300 million years Pangea existed
-later split into the North:laurasia
South:Gondwanaland - 32why might earthquakes occur away from plate boundaries-mining
-fracking
-dams
-isostatic uplift
-reactivation of old fault lines - 33constructive plate margins-two plates moving apart
(diverging) - 34Mid Atlantic ridge-discovered in 1948
-ran from north the south in the Atlantic Ocean
-1000km wide, 2.5km heights
-composed of volcanic rocks - 35Harry Hess-1962 updated wegeners tides
-studied the age of the rocks on the Atlantic ocean
-finding the youngest in the middle and the oldest nearest the USA and the carribean - 36Destructive plate margins-continental & continental
-lower density
-not much subduction
-no volcanic activity
-trigger shallow focus earthquakes
-fold mountains
INDO_AUSTRALIAN to EURASIAN - 37Oceanic-Continental covergence-denser oceanic plate is forced under the lighter continental
-earthquakes: yes
-volcanoes: yes
-deep sea trenches and hound - 38Conservative plate margins-passive or slip margins
-two plates meet and the direction of the plate motion is either parallel or nearly parallel
-SAN ANDREA FAULT & ALPINE FAULT
-no crust is formed or destroyed
-earthquakes - 39Hot springs-when a spring flows to close to an area of recent intrusive activity, the water is heated thus 'hot spring'
-temperatures vary from 20-90
-high in mineral content
YELLOWSTONE - 40geysers-groundwater is heated above boiling point by magma, the water becomes pressurised and forces its way to surface
YELLOWSTONE - 41Boiling mud-hot spring water mixes with soil to create a hot muddy pool
-can be brightly coloured because of mineral content
YELLOWSTONE - 42solfatara-steam and water mixed with sulphur rich gases to give volcanic areas
-volcanic areas without cones
ITALY - 43fumaroles-as the pressure drops when the water emerges from the ground it turns into steam
- 44Name the extrusive features-hot springs
-geysers
-boiling mud
-solfatara
-fumaroles - 45Name the intrusive landforms-batholith
-metaphoric aureole
-sills
-dukes
-laccoliths - 46batholith-formed when magma chambers cool and solidify underground, as it cools large crystals form
-large shape domes, igneous rock
-can be 700km in diameter
DARTMOOR - 47sillsWhen magma has been squeezed horizontally between existing rock strata
-cools rapidly and solidifies
-vertical cooling cracks
DUFTON - 48dykes-magma is squeezed vertically upwards cutting across bedding planes of sedimentary rocks
-vertical intrusions with horizontal cooling cracks
SKYE - 49laccoliths-magma pushes through layers of rock above it and pools in a dome shape
-planar base
-EILDON HILLS - 50Metaphoric aureole-outer edge of the magma is in contact with existing rocks, and the heat and pressure changes the rock through metamorphosis
LIMESTONE TO MARBLE
HENRY MOUNTAINS - 51rhyolitic lava-silica more than 63%
-can erupt at relatively low temperatures (650-750)
-highly viscous (not very fluid)
-forms blockages
-explosive nature
-eruptions short
LASSEN PEAK - 52Name the 3 types of lava-basaltic
-rhyolitic
-andesitic - 53andesitic lava1. 52-63% silica
2.produces the mineral andesite
3. Lava between 750-950
4.less viscous than rhyolitic
-short lived
SOUFRIERE HILLS - 54basaltic-above 950
-low viscosity
-aren't violent
-flows considerable distances
HAWAIIAN ISLANDS - 55VEI SCALE-volcanoes are measured by the volcanic exclusivity index
-several volcanic characteristics to judge
-uses a logarithmic scale
-higher up the scale you go, the less frequent it is - 56Primary effects of volcanoes-lava flows
-pyroclastic flows
-tephra
-volcanic gases - 57Pyroclastic flows-very hot (800), gas charged, high viscosity flows made up of a mixture of gases and tephra
-cause death by suffocation and burning
-travel rapidly - 58tephra-solid material varying in size from bombs to ash
-causes collapsing roofs affect areas far away from the volcano
-have high density - 59Volcanic gases-including carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine
-emissions on CO2 caused 1,700 deaths from LAKE NYOS IN CAMEROON - 60Lava flows-streams of molten rocks
-erupted during either non-explosive activity or explosive lava fountains
-destroy everything - 61Secondary effects of volcanoes-lahars
-debris avalanches
-flooding
-atmospheric effects
-famine and disease - 62Famine and disease-ash falls causes extensive crop damage and kill livestock
-people have to evacuate, breakdown of sewerage and water systems - 63Atmospheric effects-ejection of vast amounts of volcanic debris into the atmosphere can reduce global temperatures
-MT PINATUBO FELL BY 0.5
-ground aircraft, particles get into the engine - 64Flooding Effects-drainage systems can become blocked by deposition of pyroclastic flows and lava
-create temporary dams
-can melt snow and ice
ICELAND - 65Debris avalanches-volcanic mountains tend to be overstepped due to new material, inflation, magma intrudes
-results in landslides - 66lahars-heat off the volcano melts snow or ice
-mudflows are a mixture of water and sediment - 67how are convection currents formed1.radioactive decay of some elements in the mantle and core (uranium)
2.when lower parts of the asthenosphere heat up they become less dense and slowly rise
3.as they move to the top of the asthenosphere they cool down, become more dense, then slowly sink
4.these circular movements of semi molten rock are called CONVECTION CURRENTS - 68describe the structure of the earth-draw a labelled diagram
-inner core (nickel and iron)
-outer core, semi molten (iron and nickel)
-mantle (2,900km thick
made of semi molten rock: silicate, iron)
-lithosphere (mantle and crust)
-asthenosphere
-crust (two types of crust continental and oceanic) - 69describe and explain how convection currents cause tectonic plates to move-tectonic plates are moved by convection currents that flow in the asthenosphere
-how convection currents are created
-convection currents create drag on the base of the tectonic plates, which causes them to move
-diagram - 70briefly describe sea floor spreading-rising convection currents diverge at the base of the lithosphere
-the drag causes them to move
-magma rises up to fill the gap created, then cools to form new crust
-sea floor gets wider
-creates MID OCEAN RIDGES - 71constructive marginplates are moving apart
(diverging) - 72two landforms formed at constructive marginsmid ocean ridges
rift valleys - 73how is a mid ocean ridge created-where diverging plates are underwater, a mid ocean forms
- 74how is a rift valley created?-where plates diverge beneath land
-rising magma causes the continental crust to bulge and fracture, forming fault lines
-as the plates move apart, the crust between the parallel faults drops down
EAST AFRICAN RIFT VALLEY - 75describe the features of constructive plate margins-two plates move apart
-can occur on land or water
-mid ocean ridges diverge underwater(Eurasian and N USA)
-rift valleys diverge beneath land
-earthquakes - 76where is basaltic lava made?constructive
- 77where is andesitic lava made?destructive
- 78where is rhyolitic lava madedestructive
- 79name the different types of volcanoes-dome
-caldera
-fissure
-shield - 80explain a dome volcano-often at destructive margin
-lava tends to be either rhyolitic or andesitic
-steep sides, caused by high viscosity, flows short distances
layers of lava
-PUY DE DOME, FRANCE - 81explain a shield volcano-gentle sloping sides, caused by low viscosity lava, flows long distances
-layers of lava
-occur at constructive margins or hot spots
--basaltic lava
-MAUNA LOA, HAWAII - 82explain a caldera volcano-very wide circular crater, can be 7km across
-central part of the volcano has collapsed
-layers of lava, or lava, ash and cinders
-destructive margins
-andesitic and rhyolitic lavas
AIRA CALDERA JAPAN - 83explain a fissure volcano-long linear vent, can be a few metres wide, but 7km long
-layers of lava
-fairly flat surface, low viscosity, flows
-constructive margins
-basaltic lava
-LAKI FISSURE SYSTEM, ICELAND - 84what are earthquakes caused by-by tension that builds up in all three plate margins
-when the plates jerk past each other it sends out seismic waves
-spread out from the focus - 85what are other possible reasons to earthquakes-mining, subsidence
-dams, pressure on surface rocks
-reactivation of old fault lines - 86what are the three main types of seismic waves-primary
-secondary
-surface waves (love&rayleigh) - 87explain primary waves-travel through solids and liquids
-push and pull the earth in the same direction as the wave is travelling
-travel the fastest - 88explain secondary waves-can travel through solids
-waves move the earth at a 90 degree to the direction of travel
-can cause a lot of damage, sheering effect
-vibrations side to side - 89explain love waves-only travel through solids
-move the surface from side to side
-cause a lot of damage, sheering effect
-more slowly that P&S waves - 90explain Rayleigh waves-can travel through liquids and solids
-move the surface in a rolling motion
-move slowly than P&S waves - 91what are earthquakes measured byseismometer
- 92how is a seismometer used-the amount of energy released can be detected
-measure the magnitude, duration and direction (horizontal or vertical) of the vibrations
-seismic records have built up over time, which can indicate the frequency - 93what are the two different scales for measuring earthquakes-richter scale
-mercalli scale - 94explain the richter scale?-scale to measure earthquake
-measures magnitude
-is a logarithmic, doesn't have a upper limit - 95explain the mercalli scale-scale to measure earthquakes
-measures the impacts
-by observations (reports and photos)
-scale between 1 and 12 - 96how can a tsunami be created?-can be triggered by underwater earthquakes
-cause the seabed to move, which displaces water
-waves radiate out from the epicentre
-greater movement of the sea floor, greater volume of water displaced - 97where are tsunami most powerful-close to the coast
-lose energy moving forward
-tsunami waves increase in height when they get close to land, energy is more concentrated, more compressed - 98characteristics of tsunamis-open ocean where the water is deep, they travel at high speeds 500-950km/h
-long wave length of about 200km
-small amplitude of 1m
-closer to land, waves slow down to 80km/h, wave length decreases to less than 20km/h, amplitude increases to a few metres - 99what factors can increase the severity of the impacts-development of a country
-population
-timing - 100earthquake case study MEDCL'Aqulia
- 101L'Aqulia location-city in the centre of Italy
-population 70,000
-prone to earthquakes
-major fault line running through the Apennine mountain range
-fault lines close to the destructive margin of the Eurasian and the African - 102L'Aqulia economic impacts-estimated $15 billion
-thousands of buildings both historic and modern were damaged
-fires in some collapsed buildings caused further damage
-bridge near fossa collapsed, water pipes - 103L'Aqulia social impacts-300 deaths
-15000 injured
-70,000 people were made homeless
-aftershocks hampered rescue efforts
-thousands of people moved away to find jobs - 104L'Aqulia environmental impacts-area around 1000km was affected by surface ruptures, rockfalls, landslides
-broken water pipe near Paganica caused a landslide
-wildlife habitats were affected - 105L'Aqulia quake information6th April 2009
3:32AM local time
focus of the earthquake was at a depth of 5 miles
epicentre close to L'Aquila
several aftershocks after the quake in the following days (5 richter scale) - 106L'Aqulia responses-camps set up for the homeless
-ambulances, fire engines and the army were sent in to rescue
-cranes and diggers used to remove rubble
-international teams with rescue dogs
-12,000 rescue and support workers
-money provided by the gov to pay rent
-4500 new buildings by end 2009 - 107L'Aqulia management strategiesBUILDING TECHNIQUES: strict building regulations, some were poorly built
SAN SALVATORE HOSPITAL
PREDICATION: seismologists were monitoring the area previous to the incident
PLANNING: civil protection department that trains volunteers to help with things like rescue operations - 108Kashmir economic impacts-$5 billion
-whole villages and thousands of buildings were destroyed
(80% Uri was destroyed)
-cost of rebuilding alone was $3.5 billion - 109Kashmir social impacts80,000 deaths
13th highest death toll
-hundreds of thousands were injured
-3 million were made homeless
-water pipelines, electricity were broken
-landslides buried people
-diarrhoea spread due to contaminate water
-freezing winter conditions followed - 110Kashmir environmental impacts-landslides and rockfalls occurred
-two major landslides in Muzaffarbad and Jhelum valley
-Jhelum was the biggest 1km wide
-ground shifted by 5m in some parts - 111Kashmir management-there was no local disaster planning
-buildings were not designed to be earthquake resistant
-many house structurally poor
-communications were poor - 112Kashmir locationnorth of Pakistan
sits on the destructive margin where the Indian is forced under the Eurasian - 113Kashmir earthquake information-8th October 2005
-8:50am
-7.6 richter scale
-focus at a depth of 16 miles
-caused a 75km crack in the earths surface
-by 27th October had 978 aftershocks (at least 4 richter scale) - 114Kashmir response-help didn't reach areas for days or weeks
-tents, blankets, medical supplies distributed
-FRC and ERRA coordinated activities
-around 40,000 people have been relocated
-new health centres have been set up
-$5.8 billion in foreign aid,
-training has been provided to help rebuild - 115MT Pinatubo locationPhilippines
south east asia
Luzon
Near city Angeles - 116MT Pinatubo plate settingdestructive margin
continental Eurasian and oceanic Philippine - 117MT Pinatubo was it a hazard?hadn't erupted since 1380 people farmed on the fertile soil
- 118MT Pinatubo social847 died
8000 homes destroyed
73000 damaged
1.2 million lost homes
70 killed by lahars - 119MT Pinatubo economic3.8 bn pesos
destroyed harvest 1991
650000 jobs lost
$700 million damage - 120MT Pinatubo environmentalash smothered fields and buildings
ash caused global temps to drop by 0.5 - 121MT Pinatubo primary response75,000 evacuated up to a radius 30km
-department of health led in the provisions of medical care
-national disaster coordinating council mobilized civilian and military resources - 122MT Pinatubo secondary responsecareful physical land use re-planning
-health and physco-social services extended
-WHO and UNICEF humanitarian relief - 123mt etna locationHAS TWO MAIN SETTLEMENTS: CATANIA AND ZAFFERANA
-MORE THAN 25% OF THE POP OF
SILICY LIVE ON THE FLANKS OF ETNA
-ITALY IS A MEDC AND HAD A
GDP PER CAPITA OF OVER $20000 IN 1991
-3,323M ON THE ISLAND OF SICILY, ITALY - 124mt etna socialNO ONE WAS KILLED OR INJURED
7 PEOPLE LOST HOMES AND FARMLAND
-DESTROYED SPRINGS, WHICH PROVIDED WATER SUPPLY TO ZAFFERNA, POP 8000 - 125mt etna economicECONOMIC COST ROSE
TO $8 MILLION - 126mt etna environmentalVINEYARDS AND CHESTNUT
ORCHARDS DESTROYED AND A
FEW SMALLER BUILDINGS - 127mt etna primary response-BUILT A LARGE BARRIER AT THE END OF VALLE DEL BOVE, 70m HIGH AND MORE THAN 400M LONG (FOR 7 MONTHS)
-JAN 1992 EARTH BARRIER 234M LONG 21M HIGH (1 month)
-THREE ADDITIONAL SMALLER EARTHERN BARRIERS, LENGTH 90-160M HEIGHT6-12M BUILT IN APRIL
- - 128MT ETNA SECONDARY RESPONSE-US AIRFORCE DROPPED CONCRETE BLOCKS AROUND THE MAIN SOURCE . THIS FAILED
-A DIVERSION CHANNEL WAS DUG AND EXPLOSIVES WERE USED TO DIVERT THE LAVA ONTO A ADJACENT FLANK
-ITALIAN NAVY BLASTED OPENINGS IN
THE LAVA TUBES, TO ENCOURAGE NEW
DIRECTION OF FLOW
-USING 7000 KG OF EXPLOSIVES, 2/3 OF THE LAVA MOVED INTO THE ARTIFICAL CHANNEL
-STOPPED 850M FROM ZAFFERANA
LOW EFFUSION RATES,
HIGH ELEVATION - 129INDIAN OCEAN TSUNAMI 2004 INFO-26TH DECEMBER 04
-INDIAN OCEAN
-INDIO-AUSTRALIAN SUBDUCTING UNDER THE EURASIAN
-MAGNITIDE:OVER 9
-SPEED 800KM PER HOUR - 130INDIAN OCEAN TSUNAMI 2004 IMPACTS125,000 DIED
5,000,000 HOMELESS
-13 COUNTRIES AFFECTED
-$4.5-5BN AID
410,000 HOUSING UNITS DESTROYED
9 RICHTER SCALE - 131INDIAN OCEAN TSUNAMI 2004 WHY WAS IT SO DEVASTATING-4th most powerful since 1900
-not very common in the Indian ocean between 1982-2002 157 tsunamis recorded
-coastal communities unaware of threat
-flat and low lying, settlements built against the coast to maximize beaches view
-densely populated (fishing villages)
-extremely poor
-no warning system only in Thailand which failed - 132INDIAN OCEAN TSUNAMI 2004 response-by 31st dec Uk public alone donated £32m
-uk gov £50m
-globally over £700m in a year
-plane load of emergency supplies
-politically instability and remoteness meant that some people couldnt recieve aid - 133how can tsunamis be reduced?behavioral responses
structural responses - 134behavioral responsesthree levels of warning
ADVISORY: earthquake has occured, which might generate a tsunami. hourly bulletins
WATCH: tsunami was or has been generated, at least 2 hours travel time. possible evacuation
WARNING:tsunami was or has been generated, which could cause damage, strongly advised to evacuate - 135structural responsesunrealistic to portect vast streches of coastline from tsunami
HOWEVER
japan are a wealthy country, number of strategies have been employed to reduce impact - 136japan structural responsesfollowing the 1933 tsunami...
land use management
-Sanriku, gov offered financial assistance to move fishing villages to higher ground
UNSUCCESSFUL- not enough land
-10m high wall constructed in Taro - 137fissurewhen two plates move apart
-basaltic lava flows a considerable distance over gentle slopes
LAKI - 138shieldgentle sloping sides built up by numerous basaltic lava flows
MAUNA LOA - 139domeacid lava quickly solidifies on exposure to air, produces a steep sided convex cone
MT PELEE - 140compositeclassically shaped
alternating types of eruption +ash
ash first then lava
MT ETNA - 141CALDERASbuild up of gases becomes extreme, huge explosions may clear the magma chamber beneath and remove the summit
KRAKATOA - 142CLASSIFICATIONICELANDIC
HAWAIIAN
STROMBOLIAN
VULCANIAN
VESUVIAN
KRAKATOAN
PELEAN - 143ICELANDICWHERE LAVA FLOWS GENTLY FROM A FISSURE
- 144HAWAIIANWHERE LAVA IS EMITTED GENTLY BUT FROM A VENT
- 145STROMBOLIANWHERE SMALL BUT VERY FREQUENT ERUPTIONS OCCUR
- 146VULCANIANMORE VIOLENT AND LESS FREQUENT
- 147KRAKATOANEXCEPTIONALLY VIOLENT EXPLOSION THAT MAY REMOVE MUCH OF THE ORIGINAL CONE
- 148PELEANVIOLENT ERUPTION IS ACCOMPANIED BY PYROCLASTIC FLOWS
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- A-Level Geography FlashCards sobre volcanoes , criado por las1365 em 10-03-2016.
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