Natural Hazards

Created by

Priscilla

Cards (38)

What are natural hazards?
A natural process which could cause death, injury, or disruption to humans, property and possessions
EG: Earthquakes, Floods
What is a geological hazard?
hazards caused by land and tectonic processes
EG: Volcanoes, Earthquakes and Landslides
What is a meteorological hazard?
hazards caused by weather and climate
EG: Tropical storm
What human factors affect the hazard risk from natural hazards?
>Population
>Whether its a HIC or LIC
>How the country can cope with extreme events
What natural factors affect the hazard risk from natural hazards?
>type of natural hazard
>frequency and magnitude of natural hazards
>physical geography of an area(flat, mountainous, landlocked)
Continental crust is thicker but less dense
Oceanic crust is thinner but more dense
What happens at a destructive plate margin? 
>The plates(continental+oceanic) move towards each other.

The oceanic plate is denser so it subducts beneath the continental plate into the mantle
Due to heat and pressure, it melts into a pool of magma
This magma rises through the cracks in the crusts
This then forms volcanoes.
What happens at constructive plate margins?
>plates move away from each other.
This causes new magma to reach the surface through the gap.
What happens at a conservative plate margin?
>plates slide past each other in opposite directions or same direction but at different speeds
At plate margins, mountains or volcanoes can be formed due to heat and pressure from the mantle.
People live by plate margins because the soil is fertile, valuable minerals are found and the land is flat for settlements.
What plate margins are volcanoes only formed at?
Destructive and constructive
What monitoring techniques are used for volcanic eruptions?
>Seismometers are used to detect earthquakes
> Thermal imaging and satellite cameras can be used to detect heat around a volcano
>Gas samples are taken and chemical sensors are used to measure sulphur levels.
What prediction techniques are used to detect earthquakes?
>Seismic records to predict the next event
>Seismometer
>Satellite surveying to track changes in the earths surface
>Water table levels as water levels fluctuate before an earthquake
What planning techniques are used for volcanic eruptions?
>Creating an exclusion zone around the volcano
>Evacuation drills
>Having an emergency supply of food
>Trained emergency services and a good communication system
What warning signs are given before a volcanic eruption occurs?
>Small earthquakes are caused as magma rises up
>Temperatures around a volcano rise as activity increases
>Gases are released when a volcano is close to erupting
What protection techniques are used for earthquakes?
>Building earthquake resistant buildings
>Raising public awareness
>Improve earthquake predictions
NEPAL EARTHQUAKE:
Causes:
>On a destructive plate margin. >Magnitude 7.9 earthquake, only 50 miles away from the capital city. >Shallow focus of 15km deep.
Primary effects:
>9,000 people died, 20K injured
>1.4 million needed food, water and shelter
>7,000 schools were destroyed
>Landslides and avalanches
Responses:
>Search and rescue teams
>Foreign aid
>Roads repaired
>rehousing project and 7000 schools repaired
>stricter controls on building codes
CHILE EARTHQUAKE:
Causes:
>On a destructive plate margin. Magnitude 8.8 earthquake shook the ground for 3 minutes, followed by a series of aftershocks and a tsunami
Effects:
>500 people died, 12K injured
>220K homes destroyed
>Lost communications and water supplies.
Management:
>Emergency services responded fast
>International aid supplied for field hospitals
>satellite phones
>Power and water restored to 90% of homes
>Rebuilding infrastructure could take up to 4 years
Earthquakes are caused when two plated become locked causing friction to build up.
From this stress, the pressure will eventually be released, triggering the plates to move into a new position.
This movement causes energy in the form of seismic waves to travel to the focus towards the epicentre.
As a result, the crust vibrates triggering an earthquake
What is global atmospheric circulation?
transfer of heat from the equator to the poles by the movement of air
What causes low pressure?
>When hot air rises
>Causes stormy cloudy weather.
What causes high pressure?
>when cold air sinks
>causes clear and calm weather
What is the distrubution of tropical storms?
in a band that lies around roughly 5-15 degrees either side of the equator
As the tropical storm intensifies, more cool air sinks in the center, creating calm and clear conditions known as the eye of the storm
When the tropical storm makes landfall, it loses its energy source, weakens, and dissipates
Formation of tropical storms:
The sun's rays heat large areas of the ocean, causing warm, moist air to rise over specific spots
When the temperature reaches 27 degrees, the rising warm air creates a low pressure system, leading to a thunderstorm and causing air to be drawn in from the trade winds
The combination of the trade winds blowing in the opposite direction and the rotation of the Earth causes the thunderstorm to start spinning
Once the storm spins faster than 74mph, a tropical storm is formed
How does Global Atmospheric Circulation affect weather around the world?
~At the Equator:
>sun is directly overhead so a lot of solar radiation is recieved.
~30 degrees north and south of the equator:
>most moisture is released as rain, there are few clouds and little rainfall so deserts are found at this latitude
UK:
~warm air rising brings a lot of cloud cover and rainfall due to westerly winds
Conditions needed for a tropical storm to form?
>Between 5-30 degrees north and south of the equator
>Sea temperstures at 27 degrees or higher
>Difference in wind speed between high and lower parts of the atmosphere have to be low
What is climate change?
longterm change in the earths climate.
What is global warming?
sharp rise in global temperatures over the last century.
What natural factors cause climate change?
>Orbital changes: climate change is linked to the Earth orbiting the sun while wobbling and tilting
>Sun spots: increases the amount of energy Earth recieves from the sun
>Volcanic eruptions: volcanoes release large amounts of dust containing gases which block sunlight and results in cooler temperatures
What human factors cause climate change?
>Greenhouse gas emissions by burning fossil fuels - solar radiation is trapped, making the Earth warmer
>deforestation
Evidence of climate change?
>Global temperature has increased by more than 0.6% since 1950
>Glaciers and ice sheets are melting, EG: the artic sea ice has declined by 10% in 30 years
>Sea levels have readon by 10-20cm in the past 100 years due to the additional water from ice and thermal expansion
What are ways to manage climate change?
>Carbon capture: new technology designed to reduce climate change
>Planting trees: increase the amount of carbon absorbed in the atmosphere
>International agreements: countries aim to cut emission by signing international deals and setting targets
>Renewable energy: replacing fossil fuels with clean/natural sources of energy
>Recycling water, using less water
Primary effects of tropical storm?
>High seas and flooding
>destroyed buildings and communication networks
>storm surges(high waves) caused by wind
Secondary effects of tropical storms?
>Crops are damaged
>Businesses are damaged
>Shortage of clean water and lack of proper sanitation
>People are left homeless
TYPHOON HAIYAN PHILIPPINES
Causes:
>super typhoon
Effects:
>6500 deaths
>130K homes destroyed
>Emotional grief for the deaths
>Contaminated water and sewage systems caused diseases
Management:
>UN raised £190M in aid
>USA and UK sent helicopter carrier ships to deliver aid in remote areas
>Education on typhoon preparedness