Hazards Flashcards
What is a natural hazard
An extreme event caused by environmental processes that can cause loss of life, damage to property and disrupt human activity
What is a tropical cyclone
A weather system of very low pressure formed over the tropical seas and involving strong winds and heavy rainfall
Eye of a tropical storm
Very low pressure, clearer skies, temperature warmer, calm
Vortex of a tropical storm
Dense cloud, violent wind in gusts, thunderstorm and torrential rain
Edge of a tropical storm
Pressure higher, temperature higher, less cloud and wind and rain
Hurricanes characteristics
Warm, moist air from tropical seas (27 degrees)
Warm sea and calm winds coming from different directions - low wind sheer
Cumulonimbus clouds (anvil shaped)
Moves towards coast at 20-50km/h
Storm surge (abnormal rise of water) at 5-8m
Winds at 120km/h
How to measure tropical storms
Saffir-Simpson Scale
1 (120km/h) - 5 (250km/h)
How does an imager work
Uses light to take a picture of the earths surface
Good for cloud formations and patterns
How does a sounder work
Sends an infrared sensor that measures temperature
It shows the energy being stored in the tropical storm and therefore intensityb
How does a radar work
It measures reflected sound waves
Shows direction and speed of the objects movement
Balsatic lava vs andestic lava
Balsatic lava is very fluid, 1200 degrees hot and fast travelling
Andestic lava is very viscous, 800 degrees and slow travelling
(Andestic lava could create a volcano plug)
Pyroclastic flow
Hot moving current of ash and gas
Can move at speeds up 450 mph and temperatures can reach 1000 C
Can only occurs when an andestic plug is formed
Gas emissions in volcanos
Sulphur, carbon dioxide and cyanide are released during volcanic eruption (potentially hazardous)
Ash clouds in volcanos
Ash is thrown into the air during violent eruptions
Causes damage by blanketing everything
Lahars in volcanos
A mudflow causes by water and debris mixing
Hot muddy flow at 90mph
Calderas in volcanos
Calderas are large and circular volcano depressions formed when magma is withdrawn or erupted from a shallow underground magma reservoir
How to measure volcanos
VEI (volcanic explosivity index)
Exponential scale
How to measure a volcano about to erupt
Thermometer (satellite/airplane/helicopter) - temperature
Spectrometer - gas emissions
Geological history
Tilt meter - land deformation
What is an earthquake
A sudden and brief period of intense shaking of the ground
What is the focus
The centre of the earthquake
Shock waves travel outwards
What is the epicentre
The point on the surface directly above the focus
What is wind sheer
difference in wind speed or direction over a small distance in the atmosphere
Measuring earthquakes
Seismometer or seismograph records the shaking of the earth
Cause of tropical cyclones
- warm wet air rises
- the higher, the more water condenses
- it rises and area of lower pressure is formed
- winds spiral because of coriolis effect
- thick layer of cool, dense cloud forms
- drawing energy form warm, tropical oceans
- eye of the storm is formed when cold air descends
Liquefaction
When focus is close to the surface and rocks are soft
Shock waves causes rocks to lose their load bearing ability
As a result the foundation of building often collapse
Scale of earthquakes
Richter scale- measures amount of energy released by an earthquake (exponential)
Mercalli scale- measures the amount of shaking and describes the effects of the earthquake
What are volcanic hotspots
Usually occur when there is a unusually hot spot of the earths mantle
These hot areas can result in large amounts of magma rising up and breaking through the crust to form a volcano
As plates move, a series of volcanos are formed
Divergent / Constructive plate boundaries
Volcanos and gentle earthquakes
Ridge push is forcing the plates apart and magma rises to fill the gap
Destructive plate boundary
Volcanos and severe, large earthquakes
Occurs when an oceanic plate is moving towards a continental plate (slab pull). The dense plate is subducted beneath the less dense plate and is dragged under
Sea floor melts and creates a magma chamber
Collision plate boundary
Causes earthquakes only
Two continental plates meet and are of equal density and strength
Causes upheaval of land and neither plate can be pushed below the other
Land between them is forced to form fold mountains
Conservative plate boundary
Forms only earthquakes
Moving against each other
Lots of friction and pressure (earthquakes near ground and therefore strong)
What is the coriolis effect
The spinning of the earth at 5 degrees north and south of the equator enables the hurricane to spin because of the coriolis effect
Reasons why people continue to live in areas at risk from hazard events
- a lack of education and awareness
- the area may offer benefits such as fertile soil
- people may not be able to move away owing to a lack of money, or not being able to find a job elsewhere
- the cities in high risk areas represent centuries of investment
What is vulnerability
The potential to be harmed by a natural hazard
Physical factors for vulnerability
Magnitude of hazard
Proximity to hazard
Prediction
Social factors for vulnerability
Age and gender of people
Population density
Governance
Economic factors for vulnerability
Level of development
Building/infrastructure standards
Short term impacts of Eyafjallajokull Volcano
The water supply was cut off for a while
Flights to Europe were cancelled (airports were losing 130 million a day)
Parts of Icelands main routeway were washed away by flash flood
Delivery trucks were held up
Long terms impacts of Eyafjallajokull Volcano
Countries like Kenya lost 2.4 million a day due to the lack of sales
Airports lost 130 million a day
Many buildings and bridges had to be rebuilt
Short term impacts of Typhoon Haiyan (Philippines)
500,000 people displaced
Electricity and phone lines went down
Transport was damaged
Long term impacts of Typhoon Haiyan
95,000 families still living in makeshift housing
Economical damage to the country
Many workers lost their income
Short term impacts of Japanese earthquake 2011
Parts of Japan were shifted 2.4 meters east
15,000 people were killed
Shipping, commuting and travelling was disrupted
Long term impacts of Japanese earthquake 2011
Thousands of building had to be rebuilt
Seawater contamination from the tsunami would affect rice crops for years
Radiation levels are well above normal
GDP shrank by 3.7 percent
Preparation for earthquakes
Warning systems (seismographs across the country), education, hazard mapping, risk assessments, evacuation, building design
Preparation for Japanese earthquake 2011
Japan is one of the only countries in the word to have an early warning system. Warnings are automatically sent to their phones Building designs (seismic base isolators)
Short term responses and aid
emergency aid, shelter and supplies
Preparation for Nepalese earthquake 2015
Knowledge - the country experiences several small to medium earthquakes a year
Earthquake survival kits - NSET has designed these emergency kits
Short term responses for Japanese earthquake
Realtime websites to find water/supplies/people
Short term responses for Nepalese earthquake
India launched 16 military helicopters and 1000 people for help
China gave 10 million dollars
5 million dollars dollars by humanitarian aid
3 million for emergency relief like assessing and search rescue and help
Long term responses for Japanese earthquake
nuclear power stations - robots are used where people cant go
rebuilding
Long term responses for Nepalese earthquake
2 million for long term rebuilding
will inaugurate a new National Disaster Risk Reduction and Management Authority
