Hazards Flashcards
Hazards can be categorised into
Magnitude
Frequency
Duration
Spatial concentrations
Speed of onset
Risk
The probability of a hazard occurring and creating loss
The exposure of people to a hazardous event presenting a potential threat to themselves, their possessions and the built environment in which they live
Vulnerability
Risk and ability to cope
HICs may be less vulnerable as they have more money to recover
Hazard
A threat which ahs the potential to cause injury, loss of life, damage to property, socio-economic disruption or environmental degradation. Can be caused by either natural or human processes
Natural hazards
Hazards which occur in the physical environments of the atmosphere, lithosphere, and the hydrosphere
Disaster
Hazardous event that causes unacceptably large numbers of fatalities and/or overwhelming property damage. Occur as a result of a hazard
UN classifies a hazard a disaster when:
>10 people killed
>100 people affected
State of emergency is declared
Request by government for international assistance
Categories of natural hazards
Geophysical - caused by movements of the earth
Atmospheric - weather related
Hydrological - water-related hazards
Factors that influence your perception of a hazard
Previously affected by a disaster - may be more wary next time it happens - takes more precautions
Never affected by a disaster - may be naive to how much the hazard will affect them or perhaps be overly worried
Primary sector worker - industry may be more likely to be affected - crops dying, injuries preventing physical labour, rural land rendered inaccessible
Tertiary sector worker - may be less affected as a lot of money will be focussed on rebuilding the tertiary sector. If can’t go to work likely to still be paid
Highly educated - more likely to know the affects of the disaster
Poorly educated, suspicious of the media - less likely to know how the disaster will impact them, won’t believe new coverage of the event
Integrated risk management
Often used when incorporated identification of the hazard, analysis of the risks, establishing priorities, treating the risk and implementing a risk reduction plan
Prediction
Key is to improve monitoring which means warning can be issued
+
Grindavik - predicted volcano and everyone was evacuated
-
Haiyan - didn’t correctly predict route
Protection
Aim is to protect people, their possessions and the built environment. Usually involves modifications to the built environment
+
Storm surge sea walls in East USA
-
Fukushima nuclear power station - tsunami wall failed
Prevention
For natural hazards it is probably unrealistic although there have been ideas such as cloud seeding in potential tropical storms
+
Otley flood prevention
-
Carlisle flood defence didn’t work
Risk sharing
Involves pre-arranged measures that aim to reduce effects of hazard. Working together to reduce + sharing the costs of hazard response
+
Emergency shelters in hurricanes
-
Hurricane Katrina
How can we track tropical storms
Computer tracking programmes - forecast paths
Satellite + radar systems - maintain watch on progress
Tracking stations in hurricane hotspots - Miami + Japan
How predictable are tropical storms
Clearly seen, can be tracked by satellite
The specific requirements mean that scientists know when and where they will form
HOWEVER
Each hurricane is unique both in its own structure and dynamics and its meteorological
Small changes in the early development of tropical storms can have massive impacts later on
Storm surges
Pose the greatest threat to life from all hazards created by tropical storms
An abnormal rise of water generated by a storm’s winds. Storm surge can reach heights of 20ft and can span hundreds of miles of coastline
Can result in loss of life, buildings destroyed, beach + dune erosion, and road and bridge damage
Heavy rainfall from tropical storms
Tropical storms often produce widespread torrential rains in excess of 6 inches
May result in destructive floods - major threat for people living inland
Rainfall amounts related to speed and size of the storm
High winds in tropical storms
Tropical storm-force winds are strong enough to be dangerous if caught in them
Hurricane-force winds, 74-150+ mph winds can destroy homes and buildings
Wind force measured by Saffir-Simpson scale
Landslides from tropical storms
Increased flooding may cause landslides in mountainous regions
Can cause the destruction of crops, roads, bridges and villages. Most areas along US coastline prone to hurricanes are not very mountainous. The most susceptible places are central American and NW Pacific
e.g. intense rain from Hurricane Mitch (>4in/hour) caused a massive landslide on a volcano in Honduras
Ground fire
Burns beneath the ground in layers of organic peat
Surface fire
Burns across surface vegetation
Crown fire
Spreads across tree canopies + affects forested areas
BAD
Ladder effect in wildfires
Describes the process of fires spreading from the forest floor to the canopy
Distribution of wildfires
Hot places
Benefits of wildfires
Small regular areas burning can reduce amounts of fuel, lowering the likelihood of large fires
Remove alien plants
Ashes add nutrients (previously locked in other vegetation) to the toil
Controlling insects by killing off older or diseased trees
Human causes of wildfire
Cigarettes
Campfires + barbecues
Fireworks
Arson (biggest cause)
Physical causes of wildfire
Lightning - biggest cause
Volcanic eruptions
Spontaneous heating - occurs when high dry material and no flow of cooling air
El Nino
Drought
Primary effects of wildfire
Smoke
Destruction of property + possessions
Loss of life + injury
Loss of vegetation + crops
Loss of animal habitats
Secondary effects of wildfire
Increased soil erosion as vegetation is no longer there the bind the soil
Loss of jobs + income for agricultural workers who lose crops
Homelessness
Insurance premiums rise
Access to recreational areas is restricted
Health problems from inhalation of smoke
Disaster relief cycle in wildfire
Preparation (making buildings and residents ready) → Mitigation (reducing the potential severity of impact) → Response (dealing with immediate threat) → Reflection → Recovery (healing and regaining control) → Adaptation (making change to meet needs)
Response to wildfires
Fire lines - a break is made in the vegetation to try and prevent the wildfire from spreading
Firefighters spray the fire with water and foam
Spray ahead of wildfires to prevent spreading
Back burning areas ahead of the fire are sprayed to reduce fuel
Air drops - fire retardant dropped on fire
Preparation for wildlife for homes
Have a fire hose
No dense trees near the house
Mowing vegetation 100ft away from house
Burnable materials (e.g. woodpile) kept away from the house
Avoid outdoor burning
El Nino
Happens when weakening trade winds allow the warmer water from the western Pacific to flow toward the east. The clouds and rainstorms associated with warm ocean waters also shift toward the east, leaving drier conditions in Australia.
Tropical thunderstorms are fuelled by hot, humid air over the oceans. The hotter the air, the stronger and bigger the thunderstorms. As the Pacific’s warmest water spreads eastward, the biggest thunderstorms move with it. This increases the intensity and frequency of tropical storms forming over the Pacific.
What makes people vulnerable to wildfires
Geographical positioning - El Nino, Indian Ocean Dipole, high pressure
↑ urban sprawl and population means more people living near forests etc
Drought
Downwind from dry winds
Areas inland with lots of vegetation/type of vegetation
↑ rural populations
Crust
Continental (30-50km)/oceanic crust (5-10km)
Heat from the core
> 5000 C
Primordial heat left from Earth’s formation is trapped
Radiogenic heat produced by radioactive decay
Biological evidence for plate tectonics
Fossils found in areas that weren’t near each other so concluded that they used to be - Pangaea - and that’s why fossil evidence can be found on different continents
Fossil brachiopods found in India are comparable with ones in Australia
Fossilised remains of a plant which existed when coal was being formed have been located only in India and Antarctica
Geological evidence for plate tectonics
South America fits with Africa
Evidence of a late-Carboniferous glaciation deposits found in SA, Antarctica and India, the formation of these cannot be explained by their current position
Rock sequences in northern Scotland closely match formations in eastern Canada and Appalachia
Sea-floor spread - stripes of metals are magnetised according to polarity of earth which flips every 400k years. Evidence of sea floor spread as the magnetic bands are mirrored either side of the mid-Atlantic ridge
Characteristics of young fold mountains
High peaks (>6km), steep slopes, deep valleys
Glaciers
River sources due to snow melt
No volcanoes at destructive but yes at collision
e.g. Himalayas
Collision plate boundary
Convergence of two continental plates
