The concept of vulnerability to geophysical hazards

Vulnerability in the context of geophysical hazards refers to the conditions that make a community more susceptible to the impacts of natural disasters. It encompasses not only the physical exposure to hazards but also the social, economic, and political circumstances that affect how severely a community is impacted by such events.

Defining vulnerability

• Geographic conditions - The physical location and environment of a community can heighten exposure to hazards like earthquakes or floods.
• Status of people and property - The socio-economic state of individuals and the quality of infrastructure play a critical role in determining the extent of damage and recovery potential.
• Impact of catastrophic events - Vulnerability is particularly evident during major disasters, where pre-existing conditions can amplify the effects of a hazard.

Factors increasing vulnerability to natural hazards

Several factors contribute to a community's vulnerability, making some groups more prone to the devastating effects of natural hazards. These factors span economic, social, demographic, and political dimensions, each influencing how a community prepares for and responds to disasters.

Economic factors influencing vulnerability

• Levels of wealth and development - Communities with lower income levels often live in substandard housing, which is more likely to collapse during a hazard.
• Building styles and codes - Poor construction practices, as seen in the 2010 Haiti earthquake, result in buildings that fail under stress.
• Access to technology - Limited access to communication tools means less ability to receive timely warnings or forecasts about impending hazards.
• Insurance cover - Economically disadvantaged groups often lack insurance, leaving them without financial protection to rebuild after a disaster.

Social factors influencing vulnerability

• Education levels - Higher education often correlates with better income, enabling access to safer housing and resources.
• Public education programmes - Initiatives like those in Japan have equipped communities with knowledge on how to respond to earthquakes effectively.
• Awareness of hazards - Events such as the 2004 South Asia tsunami have heightened public understanding of specific dangers like tsunamis.
• Gender roles - Women, often primary carers for children and elderly relatives, may face additional responsibilities and risks during and after a hazard.

Demographic factors influencing vulnerability

• Population density - High-density urban areas, such as Port-au-Prince in Haiti, face greater risks due to the concentration of people and infrastructure.
• Age demographics - Older individuals may have reduced mobility, making evacuation or response more challenging during a hazard.
• Disability challenges - Those with disabilities are at higher risk, as evidenced by the doubled mortality rate during the 2011 Japanese tsunami.

Political factors influencing vulnerability

• Nature of governance - Ineffective or unresponsive governments, like in Myanmar during Cyclone Nargis in 2008, can worsen outcomes by delaying or blocking aid.
• Effectiveness of communication - Strong governmental response, such as China’s mobilisation of 100,000 troops after the 2008 Sichuan earthquake, can mitigate impacts by ensuring swift aid delivery and coordination.

The progression of vulnerability through root causes to disasters

Vulnerability to geophysical hazards is not a static condition but a process that evolves through interconnected stages. This progression highlights how underlying issues build up over time, ultimately increasing the risk of disaster when a hazard strikes.

Stages in the progression of vulnerability

1. Root causes - These are the foundational issues that set the stage for vulnerability:
   • Limited access to power, structures, and resources, which restricts a community's ability to prepare or protect itself.
   • Ideologies embedded in political and economic systems that may prioritise certain groups or neglect others.
2. Dynamic pressures - These are intermediate factors that exacerbate root causes:
   • Lack of local institutions, training, appropriate skills, investments, markets, press freedom, and ethical standards in public life, all of which hinder effective preparation and response.
   • Macro-forces such as rapid population growth, urbanisation, arms expenditure, debt repayment pressures, deforestation, and declining soil productivity, which strain resources and infrastructure.
3. Unsafe conditions - The direct outcomes of root causes and dynamic pressures, creating environments prone to disaster:
   • Fragile physical environments with dangerous locations and unprotected buildings or infrastructure.
   • Fragile local economies where livelihoods are at risk and income levels are low.
   • Vulnerable societies with special groups at risk and a lack of supportive local institutions.
   • Public actions marked by insufficient disaster preparedness and the prevalence of endemic diseases.

Outcome of progression

The culmination of these stages results in heightened vulnerability, which, when combined with a natural hazard, leads to a disaster. This progression underscores the importance of addressing underlying issues to reduce overall risk.

The relationship between hazard, vulnerability, and disaster risk

Understanding the link between hazards, vulnerability, and the resulting disaster risk is crucial for mitigating the impacts of geophysical events. This relationship is often expressed through a simple conceptual formula.

Defining disaster risk

Disaster risk is determined by the interaction of a natural hazard with a community's vulnerability. A hazard alone does not cause a disaster; it is the presence of vulnerability that transforms a hazard into a catastrophic event.

Formula for disaster risk

$R=H+V$

Where:

• R = Risk of disaster
• H = Hazard (natural events such as earthquakes, floods, or volcanic eruptions)
• V = Vulnerability (conditions that increase susceptibility to the hazard)

Types of natural hazards contributing to risk

• Earthquakes
• High winds (cyclones, hurricanes, typhoons)
• Flooding
• Volcanic eruptions
• Landslides
• Droughts
• Viruses and pests