The Challenge of Natural Hazards Flashcards
What is a natural hazard?
A natural process which could cause death, injury and disruption to humans
What is a geological hazard?
A hazard caused by land and tectonic processes
Name one example of a geological hazard
Volcanoes, earthquakes, landslides or avalanches
What is a meteorological hazard?
A hazard that is caused by weather and climate
Name on example of a meteorological hazard
Tropical storms, droughts, cold spells or climate change
What factors increase the risk of being affected by a natural hazard?
Densely populated areas
Low income so lack of knowledge or protection
Severity of the event eg a powerful earthquake
Name the four parts to the structure of the earth
Crust, mantle, outer core, inner core
What is the difference between continental crust and oceanic crust?
Continental crust is thicker (30-50km) and less dense. Oceanic crust is thinner (5-10km) and more dense.
Describe what happens on a destructive plate margin
- Two plates are moving towards each other
- The denser oceanic plate is forced underneath continental plate.
- As it is forced down the friction causes the oceanic plate to melt.
- As the magma rises back up to the surface a volcano is created.
- Fold mountains are also created as the land is crumpled when the two plates collide.
- An ocean trench is created where the oceanic plate is being pulled down.
A good example is the Nazca and the South American plate.
Describe what happens on a constructive plate margin
- Two plates are moving away from each other
- Magma (molten rock) rises from the mantle to fill the gap.
- As this cools it creates new crust
A good example is Iceland on the Mid Atlantic ridge
Describe what happens on a conservative plate margin
- Two plates are moving sideways past each other or in the same direction but at a different rate
- Where the plates edges are jagged, they get stuck. Pressure builds up and is eventually released as an earthquake.
The San Andreas fault line in west coast of the USA is a good example
What plate margin does not lead to the creation of a volcano?
Conservative
Which plate margin is more violent?
Destructive
Which type of earthquake is more severe - shallow focus or deep focus?
Shallow focus. This means the plate movement has happened closer to the ground surface. This leads to more damage on the earth surface.
What is the epicentre?
The point directly above the focus of the earthquake
How are earthquakes measured?
On the Richter Scale.
How does the Richter scale work?
It is a logarithmic scale so each step up on the Richter scale is 10x worse than the one before so a 6 is 10 times worse than a 5. There is also no upper limit but the highest recorded is a 9.1 in Alaska.
Name the primary effects of an earthquake
Building collapse; Injury and death to people through the collapsed buildings or falling debris; Infrastructure (roads, railways, ports and airports) damaged; electricity cables; gas and water pipes and communication networks are damaged, cutting off supplies.
Name the secondary effects of an earthquake
Landslides; tsunamis; fires caused by leaking pipes; homelessness; shortage of clean water so disease can spread; emergency aid struggles to get through as roads are blocked; unemployment as businesses including the tourist industry are affected; high cost of repairs damaging the economy of the country.
What are the immediate responses to an earthquake?
Rescue trapped people; recover dead bodies to prevent the spread of disease; put out fires; set up temporary shelters; provide temporary supplies of water, food, gas and electricity; foreign governments and charities may send aid.
What are the long term responses to an earthquake?
Rehouse people who have lost their homes; repair and rebuild buildings and roads; reconnect broken electricity, water and gas pipes; improve building regulations; set up initiatives to improve economy and boost tourism.
When was the Chile earthquake?
February 2010
What was the Chile earthquake on the Richter scale?
Magnitude 8.8
How many people died in the Chilean earthquake?
500 people
How many people were injured in the Chilean earthquake?
12,000 people
How much did the Chilean earthquake cost?
$30 billion
When was the Nepal earthquake?
April 2015
What was the Nepal earthquake on the Richter scale?
Magnitude 7.9
How many people died in the Nepal earthquake?
9000 people
How many people were injured in the Nepal earthquake?
20,000 people
how much did the Nepalese earthquake cost?
$5 billion
Name two immediate responses to the Chile earthquake
Key roads repaired within 24 hours; 30,000 emergency wooden shelters built; Swift response of emergency services
Name two immediate responses to the Nepal earthquake
300.000 temporarily migrated from Kathmandu; helicopters did search and rescue and supply drops in remote areas such as on Mount Everest; Overseas aid.
Name two long term responses to the Chile earthquake
Strong economy reduced the need for need for foreign aid; 200,000 households reconstructed; full recovery within four years.
Why do people live near places at risk from tectonic hazards?
Poor people have no choice
Earthquakes and volcanic eruptions are rare
Earthquake resistant buildings
Benefits of fertile soil and minerals
Name the four ways tectonic hazards can be reduced
Monitoring, prediction, protection and planning.
How does rain form?
Air rises, it cools, condenses and rain falls
What is low pressure?
Air rising, cooling down and normally leads to rainfall.
What is high pressure?
Air falling, heating up, moisture is evaporated and clear skies happen.
Name the three cells involved in the global circulation model
Hadley, Ferrel and Polar cell
What position is the UK in?
Between the Ferrel and Polar cells, so warm subtropical air from the south meets the cold polar air in the north. This brings rainfall!!
What is a tropical storm?
Tropical strorm’s are huge storms.
What temperature does sea need to be for a tropical storm to form?
27 degrees
Where are tropical storms likely to form?
5-15 degrees north or south of the equator
What makes tropical storms spin around?
The Coriolis effect. This is the earth’s spinning.
What direction do tropical storms spin?
Anti-clockwise
Describe the step by step process that leads to the formation of tropical storms.
- Rising air draws evaporated water vapour up from the ocean surface which cools and condenses to form towering thunderstorm clouds.
- The condensing releases heat which powers the storm and draws up more water vapour.
- Multiple thunderstorms join to form a giant rotating storm.
- Coriolis effect creates a spin in the storm at over 75mph creating a vast cloud spiral with a central, calm eye of rapidly descending air.
- Prevailing winds drift the storm over the ocean surface like a spinning top, gathering strength and heat energy.
- Prevailing winds move the storm over the ocean surface.
- On reaching land the energy supply (evaporated water) is cut off and the storm will weaken.
What is the impact of climate on tropical storms?
Sea temperatures are on the increase so they could get more extreme (if they aren’t already).
When did Typhoon Haiyan happen?
November, 2013
Where did Typhoon Haiyan hit?
Philippines
Name one characteristic feature of Haiyan?
Category 5
5m storm surge
Winds 170 mph
Name three primary effects of Typhoon Haiyan
6300 killed - most in storm surge
Over 600,000 people displaced
40 000 homes destroyed or damaged
What do we mean by the term primary effect of a hazard?
The immediate effects of a hazard re death, injury, destruction
What do we mean by the secondary effect of a hazard?
The longer term impacts resulting from the primary effects eg loss of jobs, stress
Name three secondary impacts of Typhoon Haiyan
14 million affected including 6 million jobs lost
Flooding caused landslides - blocking roads and restricting access for aid workers
Infrastructure including schools destroyed
Name three immediate responses to Typhoon Haiyan
Rapid overseas aid including NGO’s
US helicopters assisted in search and rescue, and delivery of aid.
Over 1200 evacuation centres set up
Name three long term responses to Typhoon Haiyan
UN and international financial aid, supplies and medical support
Rebuilding of infrastructure
Rice farming and fishing quickly re established
What does the three P’s stand for?
Prediction, Protection and Planning
How does predicting a tropical revolving storm help?
Tracks can be predicted. Warning systems can be put in place and the severity of winds and time scale can be issued.
How does protection help with managing the impacts of a tropical revolving storm?
The design of buildings can be adapted with features like reinforced walls, roofs and window shutters. Storm drains and sea walls. Cyclone shelters such as those in Bangladesh.
How does planning help with managing the impacts of a tropical revolving storm?
Plans put in places to make communities safer eg media campaigns to make people aware of the dangers and what to do in an emergency
List the UK’s extreme weather hazards
Thunderstorms Prolonged rainfall Drought and heat waves Heavy snow Strong winds
What is your example of extreme weather in the UK?
Storm Desmond or Somerset Floods
Summarise the impacts of the Somerset Floods
600 houses flooded £10 million worth of damage 14 farms evacuated £20 million flood action plan 8km of River Tone and Parrett dredged
What evidence is there that the UK weather is becoming more extreme?
2003 heatwave – 2000 died 2007 floods – 10 died 2009 heavy snow – 20cm 2013/14 wettest winter in 250 years 2018 – Beast from the East and heatwave
Are extreme weather events on the increase?
Yes, climate change has led to more energy in the atmosphere which leads to more storms. And the atmospheric circulation can bring floods to normally dry areas and heatwaves to normally cool areas.
