Hazards Flashcards
What factors affect people’s perception of hazards? (7 points)
Socio-economic status, level of education, occupation/employment status, religion/cultural/ethnic background, family and marital status, past experience, values and personality and expectations.
What are the three ways people may perceive natural hazards?
Fatalism (acceptance), adaptation and fear.
What are the three ways natural hazards can be managed?
Prediction (monitoring), prevention and protection.
What is a pyroclastic flow?
Also known as ‘nuées ardentes’ pyroclastic flows are very hot (over 800 degrees Celsius) gas charged, high velocity flows made up of a mixture of gas and tephra. This is a primary effect of a volcanic eruption.
Name a case study for a volcanic eruption.
The eruption of Eyjafjallajökull (Iceland) April 2010 or the eruption of Mt Nyiragongo (Congo) January 2002.
The eruption of Eyjafjallajökull caused huge amounts of ice to melt. How many people had to be evacuated due to the flooding of nearby rivers?
1,000 people
Other than flooding due to ice being melted, give one primary effect of the eruption of Eyjafjallajökull and describe what this caused.
Large quantities of ash were ejected from the volcano into the higher levels of the atmosphere. The jet stream then blew this ash towards Europe which caused airlines to have to close in Europe for six days. This is the largest shut down since World War II and it is estimated that this cost airlines £130 million per day due to the closure.
What was the risk to people’s lives from the eruption of Eyjafjallajökull?
Very little risk as so few people live in this part of Iceland.
For an earthquake, which is higher up, the focus or the epicentre?
The epicentre is higher with it being on the surface. The focus is directly under the epicentre deep underground.
What is soil liquefaction caused by?
Earthquakes violently shaking soil with high water content causing it to lose it’s mechanical strength and behave like a fluid.
Name a case study for an earthquake and give it’s magnitude.
Haiti (January 2010) of magnitude 7.0 MMS (moment magnitude scale) on the Richter scale.
What was the estimated death toll from the Haiti earthquake in 2010?
100,000 to 316,000 deaths.
How many people were injured in the Haiti earthquake in January 2010?
300,000 people were injured.
How many people were made homeless after the Haiti earthquake in January 2010?
It is estimated that around 2.3 million people were made homeless.
What were the effects of the Haiti earthquake in January 2010.
Hospitals and vital infrastructure necessary to respond to the event were severely damaged or destroyed. The airport control tower, the harbour, major roads and the main prison in Port-au-Prince were destroyed leading to more difficult evacuation and support and the escape of 4,000 inmates. Schools and communications facilities were also destroyed. Water supplies and sanitation were scarce.
What is the name for plants that rely on or can tolerate fire?
Pyrophytic vegetation.
What is the name of the chemicals sprayed on fires to slow them down?
Retardants.
What conditions are required for a tropical storm to form? (5 points)
- Ocean temperature of over 27 degrees Celsius.
- Ocean depth of at least 70m
- location between 5 and 20 degrees north or south of the equator.
- low wind shear
- rapid outflow of air in the upper atmospheric circulation.
In which direction do tropical storms move?
West
On which scale are tropical storms’ magnitude measured?
The Saffir-Simpson scale.
What is the average lifespan of a tropical storm?
7-14 days
What factors affect the vulnerability of people during a tropical storm? (6 points)
- The intensity of the storm (scale 1-5)
- speed
- distance from the sea
- physical geography
- the preparations made
- warnings and community response
What is tephra?
Anything ejected from a volcano, it can range from ash to volcanic bombs.
What is a hazard?
Something that’s a potential threat to human life or property.
What are the three types of natural hazard?
Geophysical, atmospheric and hydrological.
What is risk?
The likelihood that humans will be seriously affected by a hazard.
What is vulnerability?
How susceptible a population is to the damage caused by a hazard.
State four responses to natural hazards.
Prevention, mitigation, management and fatalism.
What is risk sharing?
When people or governments share the costs of reducing a hazard.
State two ways of mitigating the impacts of a hazard.
Prediction and adaptation.
What is fatalism?
Believing that a hazard cannot be avoided and must be accepted.
What are the four stages of the hazard management cycle?
Mitigation, preparedness, response and recovery.
When can mitigation occur?
Before the hazard occurs or afterwards, during recovery.
What is the lithosphere?
The rigid part of the mantle and crust.
What is the asthenosphere?
Semi-molten upper mantle.
State three theories about how tectonic plates move.
Convection currents, slab pull and ridge push.
What is slab pull?
Where the denser crust is forced under less dense crust and the sinking of the plate edge pulls the rest of the plate towards the boundary.
What is ridge push?
At constructive plate margins where magma rises to the surface and forms new crust which expands which pushes the older crust outward.
What is an ocean ridge?
Where diverging plates are underwater and a gap between them forms where underwater volcanoes may be which may build up above sea level e.g. Iceland.
What is a rift valley and what can be found here?
Where plates diverge beneath land, a section is caused to drop down forming a rift valley which is where volcanoes are sometimes found.
Where do young fold mountains form?
Between a continental and oceanic plate.
What kind of lava forms at constructive margins? Describe it.
Basaltic lava is very hot and has low viscosity (runny).
What kind of lava forms at destructive plate boundaries? Describe it.
Andesitic lava is cooler and more viscous (less runny).
Where do volcanoes form?
On plate boundaries.
How often do basaltic lava eruptions occur and how long do they last?
Frequently and last a long time.
How often do andesitic eruptions occur and how long do they last?
Every once in a while and are short-lived.
Which eruption is more violent, basaltic or andesitic?
Andesitic
State a primary effect of a volcanic eruption to do with gases in the atmosphere.
Acid rain
What are earthquakes caused by?
A buildup of tension in all three types of plate margin.
What is classed as a major earthquake on the Richter scale?
Above magnitude 7.
