How is hazard risk determined, and why are some people more vulnerable?
Hazard risk combines the probability of an event with exposure and vulnerability, so impacts fall unevenly on people and places.
How hazard risk is determined by probability, exposure and vulnerability, why impacts are uneven, and how risk is perceived, with Tasmanian and global examples.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
Understanding why hazards harm some people far more than others is central to the unit. The key idea is that risk is not just about the physical event. Risk is commonly expressed as a relationship between the probability or hazard, the exposure of people and assets, and their vulnerability. A high-magnitude event in an unpopulated area carries low risk, while a moderate event in a densely settled, poorly prepared community can be catastrophic. This explains why disasters concentrate harm on the poor and marginalised even when the physical hazard is identical.
Exposure refers to the people, property, infrastructure and environments located where a hazard can affect them. Building on a floodplain, a coastal dune or in the bushland-urban interface increases exposure. Vulnerability is the susceptibility to harm and the limited capacity to cope and recover. It has physical, social, economic and environmental dimensions. Physical vulnerability includes weak buildings and poor infrastructure. Social vulnerability includes age, health, isolation, language and access to information; the very old, the very young and people with disabilities are often most at risk. Economic vulnerability includes poverty and lack of insurance or savings, which slows recovery.
The flip side of vulnerability is resilience and adaptive capacity: the resources, knowledge, social connections and institutions that help a community absorb a shock and bounce back. Wealthier, better-organised communities with strong warning systems, building codes and insurance generally have higher resilience. This is why high-income countries often suffer high economic losses but fewer deaths, while low-income countries may suffer fewer dollar losses but far higher death tolls from a comparable event.
Risk perception also shapes outcomes. People do not respond to objective risk alone but to how they perceive it, which is influenced by experience, culture, trust in authorities, the visibility of the hazard and the perceived benefits of living in a hazardous area. Many Tasmanians choose to live in scenic bushland or coastal settings despite bushfire and erosion risk because they value the lifestyle and may underestimate the danger, especially if no major event has occurred in living memory. Misjudged perception can lead people to ignore warnings or build in dangerous locations.
Tasmania offers clear examples. In the bushland-urban interface around Hobart and in towns such as those affected by past fires, exposure is high where housing meets flammable vegetation, and vulnerability rises for elderly residents, people without vehicles and those on single-access roads. The 2016 floods exposed properties and farmland on floodplains, with recovery shaped by insurance and resources. Coastal communities on low-lying or eroding shores face rising exposure as sea levels rise. Globally, vulnerability patterns explain why cyclones in the Bay of Bengal or earthquakes in poorer regions cause disproportionate harm.
For assessment, be able to break a scenario into probability, exposure and vulnerability, identify which social and economic groups are most vulnerable and why, and discuss how risk perception influences behaviour. This analysis sets up the evaluation of risk-management strategies, where the goal is to reduce exposure and vulnerability and to build resilience across all groups, not just the well-resourced.