Weather GW 3 And Plate Tectonics 🔴🔴 WE NEED WEATHER GW 1-2 Flashcards
What are cyclones and where
Weather systems that dev over warm oceans in the tropics
Lat. 8-15• N and S of equator : requires warm waters in presence of coriolis effect
Warm waters: above 26.5•c
Move westward
Recall the pic of the cyclone cross section
Eye wall! Sun bands! Wind up! Rain!!
Cyclones: storm surges
Sudden rise of sea level : water is piled up against coastline beyond normal conditions. Causes property damage and massive flooding thus damage and death.
2008 hurricane ike caused storm surge between 4-6 metres in Texas. Est property damage was 24.9 bil usd
Cyclones: Strong winds
Strong force of winds damage or destroy infrastructure and injure ppl
Causes loose debris to fly and hit ppl and buildings
Large impact area
1992 hurricane Andrew had wind speeds up to 117 km per hour - widespread damage to Bahamas and parts of USA. Damage to infra and disrupted power supply - 150k homes w/o electricity
Cyclones: torrential rains
Large amt of rainfall that result in flooding inland : sudden water adds to rivers and streams- overflow
2003 hurricane Isabel flooded rivers in Virginia, Maryland, Delaware, and Washington DC in USA. Flood area abt 120 times sg, damages of >US 2.23 bil
Physical impacts of cyclones (2)
Damage to infrastructure : storm surges- huge waves crash down, flooding, damage
Disruption of comms : electrical wires topple, Comm buildings destroyed - ppl cannot go to work- econ affected // - ppl cannot seek help- death and injuries
2009 typhoon Ketsuna damaged road network in Philippines, Cambodia and Laos. 80% of health centres in Manila (Philippines) was destroyed. Difficult to distribute meds and food
Economic impact of cyclones (2)
Cost to repair infrastructure: storm surges- lots of buildings destroyed - costly repairs- less $ to dev other parts of food
Hurricane Katrina 2005 hit East Coast of USA cost 81 bil usd, large part was repair of 200k homes
Loss of income due to destroyed crops: farmlands destroyed- no crops to sell- loss of income, food shortage
Cyclone Yasu hit North Queensland Australia 2012, 75% banana crop (US350 mil) destroyed
Social impacts of cyclones 3
Disruption to water supply : water pipes burst/ contaminated
2009 cyclone alia hit West Bengal India caused cholera outbreak 1000 infected 14 deaths
Spread of diseases : flooding- breeding ground for mosquitoes (mosquito borne diseases)
Hurricane Mitch 1998, cases of dengue in Guatemala and Nicaragua due to flooding.
Displacement of ppl from homes : flooding- homes destroyed - homelessness
Hurricane Katrina struck New Orleans USA in 2005 thousands of ppl lost homes
Responses and measures to cyclones: emergency action
Emergency action- weather warnings and advisories :
evac to cyclone proof shelters, reduce death
eg. India and
Bangladesh - lower death during 2009 Aila due to network of 2500 shelters and sms warning
Responses and measures for cyclones : prediction and warning
Establishes pattern of occurrence and severity of damage: by analysing pattern, predict
Meteorologists studying 2005 Katrina warned for evacuation before 2008 Ike moved into Texas
L: records only indicate frequency, no accurate details
Response and measures for cyclones: regulate land use
Regulates land use - flood/coastal plain management
Practiced in hurricane prone areas eg. New Orleans and coastal japan and Taiwan - vulnerable to storm surges
L: authorities need to enforce the rules- req time and manpower. Coastal residents often reluctant to move out- costly to buy back land
Response and measures to cyclones: Reducing infrastructure vulnerability
Buildings designed to resistant against wind and water damage
- galvanised steel hurricane tiles on roof: not blown off
- secondary water resistant layer on roof, prevents leaking
Houses with such in Florida USA survived 2005 Wilma
Earthquake preparedness measure: infrastructure
Advanced engineering can withstand earthquake vibrations - use of steel and reinforced concrete, damping devices such as shock absorbers and heavy wide bases
Taipei 101 has a damping device: reduce swaying by up to 40%
Less destruction , less buildings collapse , less econ and lives lost
Expensive, developing countries cannot afford
Earthquake preparedness measure: emergency drills
Practice of what to do during earthquake
Japan drills - 1st September to commemorate disaster prevention day
Ppl know what to do
Ppl may panic and forget
Earthquake preparedness measure: earthquake and tsunami monitoring systems
Earthquakes monitored by study of history of when and where, est of frequency and magnitude at fault line: prediction
Earthquake motion data gathered from observation stations in Japan
Tsunami: network of pressure sensors and seismographs, deep ocean tsunami detectors located in Hawaii
Allows ppl to evac, less loss of lives
L: only a general indication, not precise. Expensive to install and use, many not provide sufficient time, false warnings
Earthquake short term responses : search and rescue
Ppl trapped in collapsed buildings are located and freed
2011, Tohoku Japan : heat sensors and sniffer dogs were deployed
Many ppl rescued, reducing death rate
Rescue ppl have 72 hours (3 days) to find survivors
Earthquake short term responses: emergency food and medical supplies
Injured treated, provide clean drinking water - prevent dehydration and disease spread
2002 Afyon, turkey - Turkish red crescent society delivered 20k rents 50k blankets and 3k heaters
Reduce loss of lives, help injured, reduce spread of diseases
Meds and food may not be sufficient : social unrest eg. 2010 Haiti, looting and fighting broke out
Long term responses earthquake: rebuilding of infrastructure
Rebuilt and improved, dev structure building codes, endeared higher safety level than before
1995 Kobe Japan, billions spent to dev tech to build more resistant buildings
Less damage to infrastructure, less cost of rebuilding, less loss of lives
Reinforced buildings not necessarily prot against tsunamis (add. prot in form of coastal structure)
Eg. Many buildings in Chile resistant, but coastal area tsunami damage in 2010
Long term responses earthquakes: provision of healthcare
Health options such as long term counselling
A year after 2011 Christchurch NZ, significant depression and anxiety amongst affected population: more health workers in area
-
Improving health options eg. Restoring resilience
can be challenging
Why do tectonic plates move?
Convection currents
1. Mantle mat heated by core
2. Expands rises spreads out
3. Plates dragged along
4. Mantle mat sinks pulling plates along
5. Heats up and repeats
Slab pull force
1. Dense sinking oceanic plates at subduction zones pull rest of plate
2. Drives downward motion of CC
3. Mantle mat away from sub zone drives rising CC
Internal structure of earth (the pie)
Crust
- basalt, granite rocks
- few km to >10km thick
Mantle
- mostly solid rock : flows under ^temp and ^pressure
- 2900km thick
- 800-3k deg celcius
Core
Mostly iron and nickel
Liquid outer and solid inner
Temps of 3000-5000
Divergent O-O (diagram, steps, location)
The tree trunk island with ocean on both sides (the ridge)
- 2 O plates diverge, fractures formed @ plate boundary
- Magma rises @ zone of divergence, creates ridge of new ocean floor (mid-o ridge)
- @ various points, magma builds and solidifies into undersea volcanoes
- Volcanoes grow above sea level -> volcanic islands
- Sea floor spreading occurs
Mid-Atlantic ridge , NA and Eurasian
Divergent C-C (diagram, steps, example)
The layered valley thing
- 2 C plates diverge, resulting in faulting, forming fault lines
- Land between the 2 C plates sinks (forming linear depression- Rift Valley)
- Remaining highland - block mountain
East African Rift Valley system, Nubian and Somalian
Convergent O-O (diagram, steps, example)
Goes down on one side and goes up the other. Volcano on upside with ocean around
- 2 O plates converge, denser O subducts beneath less dense
- Deep O trench at subduction zone
- Subducted o plante mantle melts and forms magma
- Magma roses thru crust to form volcanoes and island chains
- Earthquakes due to friction
Mariana Trench, Mariana islands ,, pacific and Philippine
Convergent C-C (diagram, steps, location)
The mountains on the right and plate going down on the left
- 2 C plates converge so folding forming folds
- Upper layers of C crust fold upwards into fold mountains
Himalayas, Indian and Eurasian
Convergent O-C (diagram, steps, example)
Water on left, volcano on right, mountain further right continuation. Left one goes under right one
- O plate and C plate converge, denser O subducts under C
- O trench at subduction zone
- C plate buckles and folds, forming fold mountains
- At subduction zone, sinking plate mantle mats melt to magma
- Magma roses forming volcano
Sunda trench, Australian and Eurasian
Transform boundary (diagram, steps, example)
Two blocks going in different directions
- CCs pull 2 plates in parallel and opposite directions along transform boundaries
- Results in formation of transform fault
- Tremendous stress builds which is rejected in the form of violent earthquakes
- May result in further movement / faulting
- Little - no volcanic activity
North Anatolian fault - Anatolian and Eurasian
General plate tectonics diagrams rules
- label layers (crust, uppermost mantle, asthenosphere)
- movement (arrows)
- landforms
Plate tectonics boundaries abs format
- Type of plate boundary (C/D/T)
- Type of plates (C/O)
- Plate movement (towards/ away/ past)
- Forces (compressional/ tensional/ shear)
- Processes + explain (subduction, folding, faulting, sea floor spreading etc)
- Landforms formed
- Specific example
Continental plates
- buoyant, do not subduct
- instead, they fold at convergent boundaries
Sea floor spreading
- Magma rises from mantle to form new sea floor between plates as they move apart
- New lava flows out onto the sea floor and cools and solidifies - mid o ridge
- Newly formed rocks are closer, folder are further away
Plate boundaries (shield vs strato)
SH
O-O div
ST
O-O con
O-C con
Profile (shield vs strato)
SH
- gently sloping base
- broad base
ST
- high
- slightly concave
- steeper at top, gentler at base
Lava type and flow (shield vs strato)
SH
- Low silica/viscosity
- flows easily
- spreads over a large area before solidifying
ST
- high silica/viscosity
- more viscous
- traps gases more easily : build up of pressure
Eruption and eruption mats (Shield vs strato)
SH
- not explosive
- Low silica lava
ST
- explosive
- high silica lava
- pyroclasts (ash, rock frags, volcanic bombs)
- ash
Examples (shield vs strato)
Mount Washington USA
Mount Mayon, Philippines
Mount merapi, Indonesia
Labeled diagram (shield vs strato)
Sloping layers of a cake with a thick strip of magma in the middle
Tall one like a traffic cone. Layers but less. One of ems thicker. Has secondary cones
Shield volcano formation process
- CCs in mantle cause 2 O plates to diverge
- Molten magma erupts to earth surface
- Little gas and air trapped in lava : Low-silica content
- Successive eruptions - build up - formation of volcano w gentle slopes and broad bese
Stratovolcano formation
- CCs in mantle - 2 O plates to converge / C&O plates to converge
- Heavier and denser plate subducts under less dense O/C plate
- Top part of subducted plate (crust?) melts to form magma
- Magma erupts onto earths surface as lava thru faults
- A lot of gas and air trapped in lava - high silica content - explosive eruption
- Successive eruption - build up- formation of volcano w concave, steep sides, gentle base
Damages and dangers of volcanos (pyroclasts flows and lahars etc)
- made of pyroclasts and superheated gases
- up to 200m/s
- pyroclasts + water
- fast flowing mudflows
Can engulf towns and kill ppl
Volcanic bombs can cause damage to property
Landslides can bury villages and farmland
Pos and neg impacts of volcanoes 4, 2
Geothermal energy
Precious stones and minerals, building mats
Tourism
Fertile soil
Massive destruction
Pollution
Geothermal energy (pos of volc)
groundwater comes in contact w hot rocks : hot water and steam : used to turn turbines and produce electricity
Renewable source to meet ppls energy needs
Most of icelands energy gen from this due to many volcanoes. Over 70% homes heated by volcanic steam
Precious stones and minerals, building mats (pos impacts of volc)
Volcanic rocks can be rich in them and can only be extracted after millions of years
Can also be sold for ppl to earn a living and dev econ
Eg diamond, which are pressurised and heated carbon that are cooled in magma pipes. Refined diamonds used for industrial tools and sci research/ jewellery. Old volcanic rocks at Kimberley in South Africa - rich source of diamond
Fertile soil (pos impacts of volc)
Lava and ash from volc eruptions break down to form fertile soils over millions of years. Richest soils on earth, favourable for agri
Farmers - greater harvest - more food and income
Volcanic soils in Java and Bali in Indonesia support crops like tea coffee and rice. Thus able to support large rural population.
Tourism (pos impacts of volc)
Volcanic areas offer a variety of activities for tourists from scenery to history of the area
Tourism related jobs - more employment, income, benefits local econ
Pompeii Italy, the town was buried after the eruption of mount Vesuvius when it erupted in 79 CE. Almost 3 mil ppl visit the archeological site each year
Massive destruction by volcanic materials (neg impacts of volc)
Lava, pyroclasts, Lahars, ash, rock fragments and volcanic bombs : widespread damage of property and loss of life
Eruption of Nevado del Ruiz in the Andes of South America in 1985 released p.flow. mixing of pyroclasts and glacial ice : lahar. It engulfed the town of armero and killed more than 20k ppl
Lava - high temps 500-1400, burns area
Low silica - rapidly over long distance
Pyroclastic flow- destruction, hot rock fragments (ash-boulders) at >200m/s
Inhaling gases and ash - injury and death
Volcanic bombs - damage to property
Landslides - obstruct rivers (floods), roads, buried villages and farmland
Pollution (neg impacts of volc)
Ash particles/ clouds ejected during eruption disrupt human activities. It may settle on ground and block sunlight, suffocate crops and cause resp issues for ppl and animals. Can also release harmful gases.
Eruption of eyjafjallajökull in Iceland in 2010 produced extensive ash clouds which posed a danger to aircraft engines and structures. Closure of air space over much of Europe - delays to 1.2 mil passengers daily, cost the industry US1.8 bil
Earthquake preparedness measures: land use regulation
A set of rules implemented to restrict developments in certain areas. A prohibition of constructing buildings in Low lying land vulnerable to tsunamis.
California USA all new buildings are not build across fault lines or areas at risk of liquefaction.
By not having developments at high risk areas - fewer buildings damaged - fewer ppl there - fewer deaths
When carried out on built or privately owned land, Govt has to compensate ppl who have to move - costly, ppl may be reluctant
Eruption of strato steps
- As magma seeps into the magma chamber, amt of pressure builds up, erupts
- When erupt, pyroclasts released (force depends on pressure built up)
- New eruption of lava covers pyroclasts. Builds up volc
- Lava builds around vent and solidifies to form cone. Opening is called crater.
- Vent may become blocked - forces magma to find alt route - secondary cone
- Summit may be blown off during eruption - sides of crater collapse- forms caldera
creation of the eye
- Area of Low pressure at eye as warm moist air over ocean expands and rises. 2. Condensation, releases latent heat. Continuous large scale release of it heats air, thus expanding and rising further.
- Reduces air pressure at earth surface, creating and sustaining area of Low pressure at centre.
- As warm air rises it cools and sinks. Descending dry air creates environment at center called The Eye.
Why do cyclones need coriolis effect
Strong pressure gradient causes air to move inwards to the cyclone
Due to coriolis effect air moves at angle thus beginning the rotary motions.
They do not form 5 dev N and S due to weak C effect
NH- deflect right - rotate anti clockwise
SH- deflect left - clockwise
Impacts of earthquakes 4
- affected water pipes/ electricity affected
- destruction of infrastructure
- landslides
- tsunamis
Factors affecting compact of earthquakes
- dist from epicentre
- magnitude
- time
- population density
- type of soil
- level of prep
