Natural Hazards Flashcards
TECTONICS AND TROPICAL STORMS
Natural hazards definition and examples
A natural hazard is a natural event which causes loss of life or damage to property which disrupts human activities.
Examples are tsunami‘s, earthquakes & volcanic eruption‘s
TECTONICS AND TROPICAL STORMS
Define the terms “hydro-meteorological” and “geophysical”
» hydro-meteorological is weather hazards like hurricanes or typhoons.
» geophysical is the movement of the earth, so tectonics, examples are earthquakes and volcanoes.
- tsunami‘s are also geophysical because they were caused by the movement of tectonics
TROPICAL STORMS
The definition of latitude and some important latitudes
» latitude is how far north or south you are from the equator
4 important points:
- arctic circle 66°N
- Tropic of Cancer 23.5°N
- Tropic of Capricorn 23.5°S
- Antarctic circle 66°S
TROPICAL STORMS
How do you measure them?
» Tropical storms are measured using the saffir Simpson scale; 5 being strongest and 1 being weakest
TROPICAL STORMS
How do hurricanes form?
» hurricanes form at 27°C Sea temperatures
» The warm air from thunderstorms and the deep warm ocean surface mix together and start to rise to create low pressure.
» trade winds at the equator cause the storm to spin due to the earths rotation.
» Air continues to rise and the pressure starts to decrease at higher altitudes.
» Air rises faster and draws in more warm air from the sea surface whilst sucking cooler air downwards.
» As the storm moves over the ocean, it picks up more warm moist air. The speed of its winds increase as more air is sucked in.
» it can take hours or days to fully form a hurricane. The eye has calm winds which are surrounded by a spinning vortex of high winds and heavy rain (eye wall).
TROPICAL STORMS
Low pressure & high pressure
Low pressure - warm air rises, unsettled weather
High pressure - cool air sinks, lots of air pushing on the floor. (Can be settled cold weather too)
TROPICAL STORMS
Why is the equator hot?
- At the equator the sunlight is hitting the earth straight on, the insulation is focused on a small area making it more powerful.
- The atmosphere is thinner there which means the sun‘s rays can travel through it more easily, and so are warmer when they reach the Earth, making the temperatures higher.
» at high latitude‘s, the insulation is spread over a larger area.
» the atmosphere is also thicker, meaning it’s more difficult for the suns rays to travel through, meaning they’re less warm when they reach the earth.
TROPICAL STORMS
global atmospheric circulation
The cells:
- Up north (60°) = polar cell
- middle (30°) = Ferrell cell
- equator (0°) = Hadley cell
HURRICANE KATRINA
Brief information
Date: 23 August 2005 - 31 August 2005 Hit New Orleans: 29 August 2005 Highest Wind Speed: 280km/h Category 5 Cost: $125 billion Affected areas: New Orleans, Louisiana, Alabama, Mississippi
HURRICANE KATRINA
Primary and Secondary effects
PRIMARY:
- hotels and facilities destroyed.
- Mississippi below sea level.
- 80% of New Orleans (Louisiana) under 6ft of water.
- 1836 confirmed dead and 705 missing.
SECONDARY:
- flooding damaged petrochemical plants.
- 140000 chicks lost (poultry industry)
- 1.3 million acres of trees were lost, costing $5 billion in Mississippi.
- $81 billion building damage.
HURRICANE KATRINA
Effects in certain places
Louisiana (New Orleans):
- widespread looting
- 80% submerged under 6ft of water
- 1 million evacuated, 100,000 stayed behind
Mississippi:
- 110 drowned
- 200,000 without electricity or water
- 100,000 homeless, 100,000 trailers provided
- 100 dead
HURRICANE KATRINA
Immediate and long term responses
Immediate:
- 9000 people took shelter in the New Orleans superdome
- 100,000+ trailers provided for homeless individuals
- 1 million evacuated from New Orleans, 100,000 stayed behind
Long term:
- aid offered from around the world
TECTONIC HAZARDS
What are tectonic hazards?
Tectonic hazards occur when the Earth’s crust moves.
When plates move past each other the friction can cause earthquakes, tsunamis or volcanoes to form.
TECTONIC HAZARDS
Tectonic plate boundaries
Destructive Margin:
- oceanic and continental plates meet, the denser oceanic plate is forced down (subducted) into the mantle and destroyed. Creates volcanoes and ocean trenches.
Constructive Margin:
- when two plates are moving away from each other magma rises from the mantle to fill the gap and cools creating new crust. Creates volcanoes.
Conservative Margin:
- two plates are moving sideways past each other or moving in the same direction but at different speeds, creating friction that causes earthquakes. Crust isn’t destroyed or created.
TECTONIC HAZARDS
Why do the plates move?
The heat from the radioactive processes within the planets interior causes the plates to move, sometimes towards, sometimes away from each other.
