Factors Influencing Natural Hazard Risk (Frequency of Hazard (Low…
Factors Influencing Natural Hazard Risk
Relief of the land
Tropical Storm - One of the major hazards is a storm surge. If people can get to high land they are in less danger.
In an earthquake - a bowl shape can increase the shaking risk and mean more buildings collapse. E.g. Nepal EQ 2015.
This is the shape of the land.
In an EQ - liquefaction is where soil that is shaken behaves like a liquid. This causes buildings to collapse. The risk of this increases if the rock is impermeable.
Flooding - The risk is lower if houses are built on permeable rock
In an EQ soft rock will make the shaking worse - increasing the risk
Size of population
The number of people who live close to a hazard zone.
Squatter settlements - Very high risk from natural hazards. Buildings are poorly constructed and there is very high population density.
Higher population density increases the risk from hazards. More people in danger.
Frequency of Hazard
Low frequency events - high risk - people don't prepare as they feel it won't happen.
Middle frequency events - reduces the risk as people have knowledge of what to do in the event of the hazard occuring.
High frequency environment - in this case people are always recovering from the last event.
Frequency of hazard - how often the event occurs.
Magnitude of Hazard
Measure the following hazards - using a number system - EQ richter scale, volcanoes - Volcanic explosivity index, tropical storms - saffir simpson scale.
If the hazard is a larger event e.g. a more powerful EQ, then more people are likely to be affected and so the risk increases.