1.1 - Introduction to Natural Hazards - notes
1.1 - Introduction to Natural Hazards
Defining natural hazards and disasters
A natural hazard represents a potential threat to human life, health, or property due to natural processes. When such a hazard occurs and causes significant damage or loss, it is termed a natural disaster. Importantly, extreme natural events only qualify as hazards when they pose a risk to human activity. For instance, a drought in a deserted region or an avalanche in an uninhabited polar area does not constitute a hazard as it affects no one.
Key distinctions between hazards and disasters
| Term | Description |
|---|---|
| Natural hazard | A natural process with the potential to cause harm, such as death, injury, or destruction of property. |
| Natural disaster | The actual occurrence of a natural hazard resulting in significant impact on humans or their possessions. |
| Non-hazardous events | Extreme natural phenomena that do not threaten human activity, thus not classified as hazards. |
Categories of natural hazards
Natural hazards can be broadly grouped into two primary types based on their causes.
Types of natural hazards
- Geological hazards - These arise from processes related to the Earth's land and tectonic activities. Examples include:
- Earthquakes, resulting from tectonic plate movements.
- Volcanic eruptions, caused by magma reaching the surface.
- Landslides and avalanches, triggered by unstable slopes or heavy snowfall.
- Meteorological hazards - These are driven by atmospheric conditions and climate patterns. Examples include:
- Tropical storms, such as hurricanes or cyclones, formed over warm ocean waters.
- Extreme weather events, like heatwaves or severe cold spells, influenced by climatic variations.
Additionally, climate change is recognised as a factor that may heighten the frequency or severity of meteorological hazards.
Factors influencing hazard risk
Hazard risk refers to the likelihood of a natural hazard affecting people in a specific area. Several elements contribute to the level of risk associated with these events, shaping how severely a population might be impacted.
Elements affecting hazard risk
- Vulnerability - This relates to the exposure of a population to natural hazards. Areas with higher population density are more at risk. For instance:
- A densely populated coastal region prone to flooding faces heightened vulnerability.
- A city located near an active fault line is more susceptible to earthquake damage.
- Capacity to cope - The ability of a community to manage and respond to a hazard significantly affects risk levels. Factors include:
- Economic resources, where wealthier regions can invest in protective measures like flood barriers or early warning systems.
- Preparedness and infrastructure, which enable better evacuation and response strategies in higher income countries (HICs).
- Nature of natural hazards - The inherent characteristics of a hazard influence its risk potential. These include:
- Type - Some hazards, like earthquakes, strike without warning, making them harder to mitigate compared to predictable events like tropical storms.
- Frequency - Hazards that happen more regularly can pose a greater cumulative risk over time.
- Magnitude - The intensity of a hazard often determines its impact. For example, a magnitude 7.9 earthquake in a populated area could result in thousands of casualties, while a magnitude 5.2 event might cause minimal loss of life.