Disaster

Types

The scale of a disaster matters. Small-scale disasters only affect local communities but need help beyond the affected community. Large-scale disasters affect wider society and need national or international help.

Sendai Framework for Disaster Risk Reduction (2015–2030)

• For the purposes of defining the scope of the Sendai Framework for Disaster Risk Reduction (2015–2030), the following concepts are understood as follows:
  • Small-scale disasters refer to events that primarily impact local communities and exceed the capacity of those communities to respond independently, thereby requiring external assistance, although not necessarily at the national or international level.
  • Large-scale disasters are events that affect an entire society or substantial portions of it and demand coordinated responses at the national level and, in many cases, support from the international community.
  • Frequent and infrequent disasters are distinguished by the likelihood of their occurrence and the return period of the hazard involved. While infrequent disasters may cause severe immediate damage, frequent disasters can have compounding effects over time, potentially creating long-term or chronic stress for communities and societies.
  • Slow-onset disasters develop progressively over an extended period rather than occurring abruptly. These disasters are often linked to environmental or biological processes such as drought, desertification, rising sea levels, or the spread of epidemic diseases.
  • Sudden-onset disasters arise rapidly and are typically triggered by unexpected hazardous events. Examples include earthquakes, volcanic eruptions, flash floods, industrial or chemical accidents, failures of critical infrastructure, and transportation-related incidents.

It is usual to divide disasters into natural or human-made. Recently the divide between natural, man-made and man-accelerated disasters has become harder to draw. Some manufactured disasters such as smog and acid rain have been wrongly attributed to nature.

Related to natural hazards

Disasters with links to natural hazards are commonly called natural disasters. However experts have questioned this term for a long time.

A natural disaster is the very harmful impact on a society or community brought by a natural phenomenon or hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides - including submarine landslides, tropical cyclones, volcanic activity and wildfires. Additional natural hazards include blizzards, dust storms, firestorms, hails, ice storms, sinkholes, thunderstorms, tornadoes and tsunamis.

A natural disaster can cause loss of life or property damage. It typically causes economic damage. How bad the damage is depends on how well people are prepared for disasters and how strong the buildings, roads, and other structures are.

Scholars have argued the term "natural disaster" is unsuitable and should be abandoned. Instead, the simpler term disaster could be used. At the same time, the type of hazard would be specified. A disaster happens when a natural or human-made hazard impacts a vulnerable community. It results from the combination of the hazard and the exposure of a vulnerable society.

Unrelated to natural hazards

Human-made disasters are serious harmful events caused by human actions and social processes. Technological hazards also fall into this category. That is because they result in human-instigated disasters. Human-made hazards are sometimes called anthropogenic hazards. Examples include criminality, social unrest, crowd crushes, fires, transport accidents, industrial accidents, power outages, oil spills, terrorist attacks, and nuclear explosions/nuclear radiation. Catastrophic climate change, nuclear war, and bioterrorism also fall into this category.

Climate change and environmental degradation are sometimes called socio-natural hazards. These are hazards involving a combination of both natural and human factors. All disasters can be regarded as human-made, because of failure to introduce the right emergency management measures.

Famines may be caused locally by drought, flood, fire or pestilence. Long-lasting local shortages, especially during the modern era, are generally due to government mismanagement, violent conflict, or an economic system that does not distribute food where needed.

Others

Complex disasters, where there is no single root cause, are more common in developing countries. A specific hazard may also spawn a secondary disaster that increases the impact. A classic example is an earthquake that causes a tsunami. This results in coastal flooding, damaging a nuclear power plant on the coast. The Fukushima nuclear disaster is a case in point. Experts examine these cascading events to see how risks and impacts can amplify and spread. This is particularly important given the increase in climate risks.

Some researchers distinguish between recurring events like seasonal flooding and unpredictable one-off events. Recurring events often carry an estimate of how often they occur. Experts call this the return period.

Effects

The effects of a disaster include all human, material, economic and environmental losses and impacts.

The Emergency Events Database (EM-DAT) records statistics about disasters related to natural hazards. For 2023, EM-DAT recorded 399 disasters, which was higher than the 20-year average of 369.

Health effects

Injuries

In the immediate aftermath of a disaster, physical injuries are often the most urgent concern. The severity of damage to local infrastructure may require emergency responders and community health workers to establish temporary triage or treatment sites. Among natural hazards, earthquakes are generally associated with the highest number of injuries, compared to events such as floods, storms, wildfires, or tsunamis.

Chronic disease–related emergencies

Many disasters disrupt electricity, transportation, and healthcare systems, creating serious risks for individuals with chronic illnesses. People who rely on ongoing medical treatment such as those with diabetes, kidney disease, respiratory conditions, or cardiovascular disorders are particularly vulnerable when access to medication, medical equipment, or healthcare facilities is interrupted.

Hygiene and disease transmission

Damage to essential infrastructure, including water supply systems, sanitation networks, and energy services, can lead to secondary public health risks. Contaminated drinking water, nonfunctional sewage systems, and reduced waste management increase the likelihood of infectious disease outbreaks. Prolonged power outages may also compromise food safety, medication storage, and the safe operation of healthcare facilities.

Food insecurity

Disasters frequently disrupt food production and distribution systems. While supply chains may be temporarily interrupted, damage to agricultural land, livestock, or food processing facilities can create longer-term food shortages. These disruptions may contribute to rising food prices, disproportionately affecting low-income and vulnerable populations. Disasters have inflicted an estimated US$3.26 trillion in agricultural losses between 1991 and 2023, averaging at US$99 billion per year. Disaster losses in agriculture totalled US$3.26 trillion over 33 years from 1991 to 2023, with nearly US$2.9 trillion attributed to climate-related disasters, including floods, droughts and heatwaves.

Losses in the 1990s averaged US$64 billion annually; gradual increased throughout the 2000s reaching US$67 billion per year; and a severe escalation from 2010 onwards with losses at US$144 billion annually. Disasters can also disrupt access to nutritious foods, potentially forcing households to adopt quantity-over-quality approaches that emphasize staple foods over nutritious options, such as fruits and vegetables, which provide essential micronutrients. This dietary shift may occur not only due to reduced production or availability of nutritious foods but also because of increased prices, disrupted market access or reduced household income following disasters that affect purchasing power for higher-value nutritious foods.

Mental health effects

Experiencing a disaster can have significant psychological consequences. In the short term, affected populations may experience shock, fear, and grief. Over time, the loss of housing, livelihoods, and social support networks can contribute to mental health conditions such as post-traumatic stress disorder (PTSD), depression, and anxiety. Long-term impacts may also include increased rates of substance misuse.

Damage to healthcare systems

Disasters can severely impair healthcare infrastructure through physical destruction, power failures, or shortages of medical supplies. Hospitals and clinics may be unable to operate at full capacity, while damage to equipment and medication losses further limit care delivery. Population displacement following disasters can also result in healthcare workforce shortages, and in some cases, reduced incentives or resources for rebuilding health facilities.

Economic losses

Between 2016 and 2020 the total reported economic losses amounted to $293 billion. This figure is likely to be an underestimation. It is very challenging to measure the costs of disasters accurately, and many countries lack the resources and technical capacity to do so. Over the 40-year period from 1980 to 2020 losses were estimated at $5.2 trillion.

Human impacts

In 2023, natural hazard-related disasters resulted in 86,473 fatalities and affected 93.1 million people. Whilst the number of deaths was much higher than the 20-year average of 64,148, the number affected was much lower than the 20-year average of 175.5 million.

According to a UN report, 91% of deaths from hazards from 1970 to 2019 occurred in developing countries. These countries already have higher vulnerability and lower resilience to these events, which exacerbates the effects of the hazards.

Effects of climate change

Hazards such as droughts, floods, and cyclones are naturally occurring phenomena. However, climate change has caused these hazards to become more unreliable, frequent and severe. They thus contribute to disaster risks. Countries contributing most to climate change are often at the lowest risk of feeling the consequences. As of 2019, countries with the highest vulnerability per capita release the lowest amount of emissions per capita, and yet still experience the most heightened droughts and extreme precipitation.

Social, cultural, and political perspectives

Scholarly research emphasizes that disaster outcomes are shaped not only by hazardous events but also by social organization, culture, governance, and political economy. In this view, hazard is one component of risk; impacts (mortality, displacement, recovery) are patterned by exposure, vulnerability, and capacity that develop over time through land use, infrastructure, institutions, and everyday practice These perspectives inform contemporary approaches to disaster risk reduction (DRR), which focus on reducing vulnerability and exposure alongside hazard monitoring.

Cultural framings in disaster risk reduction

Cultural approaches in DRR examine how beliefs, social norms, values, and routines influence risk perception, preparedness, warning response, and recovery. Culture is treated as dynamic: people interpret hazards through shared meanings and practices that evolve with experience and institutional context. Programs can fail if they overlook local meanings or organization (e.g., warning formats, shelter rules, or rebuilding standards that conflict with livelihoods or customary tenure). Co-developed, context-sensitive strategies tend to have higher uptake. Cultural framings are also relevant to warning interpretation and “last-mile” communication. People routinely combine official alerts with heuristics, trusted peers, and place-based knowledge when deciding whether to evacuate or shelter in place. Recognizing these practices can improve message design, timing, and the selection of intermediaries (for example, local associations, faith groups, and community radio).

Preparedness as governance under uncertainty

Another strand analyzes preparedness as a form of governance. Institutions construct “security imaginaries” shared models of possible threats and appropriate countermeasures and assemble apparatuses intended to function amid uncertainty, such as surveillance networks, stockpiles, expert committees, and emergency operations centers. Preparedness necessarily entails selection: authorities decide which risks to prioritize, which capacities to fund, and how to distribute roles across levels of government and sectors. These choices shape coordination and public expectations of response capability.

In global health, preparedness has included scenario planning, early-warning and surveillance systems, and the maintenance of material reserves to ensure continuity of response when events exceed normal operating conditions. The literature emphasizes that such systems are never exhaustive: they reflect historically specific judgments about plausibility, proportionality, and acceptable trade-offs between objectives (e.g., civil liberties, economic continuity, and protection of life).

Critical disaster studies

Critical disaster studies examines how power, inequality, and historical processes shape risk, loss, and recovery. Rather than treating a disaster as an exogenous shock to an otherwise level playing field, this approach analyzes how colonialism, segregation, uneven development, and policy choices about land use and infrastructure generate differential exposure to harm and unequal access to protection and assistance.

From this perspective, there are no purely “natural” disasters: hazard interacts with socially produced vulnerability and capacity, which are distributed along lines such as class, race, gender, age, disability, and legal status.

Critical work also attends to questions of representation and voice: whose experiences are documented, which forms of knowledge inform planning, and how media or cultural narratives frame causes and consequences. It further examines the politics of aid and recovery eligibility rules, documentation requirements, and the spatial distribution of assistance and how these practices can reproduce or mitigate pre-existing inequalities.

Prevention and response

Disaster risk reduction

Disaster risk reduction aims to make disasters less likely to happen. The approach, also called DRR or disaster risk management, also aims to make disasters less damaging when they do occur. DRR aims to make communities stronger and better prepared to handle disasters. In technical terms, it aims to make them more resilient or less vulnerable. When DRR is successful, it makes communities less the vulnerable because it mitigates the effects of disasters. This means DRR can make risky events fewer and less severe. Climate change can increase climate hazards. So development efforts often consider DRR and climate change adaptation together.

It is possible to include DRR in almost all areas of development and humanitarian work. People from local communities, agencies or federal governments can all propose DRR strategies. DRR policies aim to "define goals and objectives across different timescales and with concrete targets, indicators and time frames."

Disaster response

Disaster response refers to the actions taken directly before, during, or immediately after a disaster. The objective is to save lives, ensure health and safety, and meet the subsistence needs of the people affected. It includes warning and evacuation, search and rescue, providing immediate assistance, assessing damage, continuing assistance, and the immediate restoration or construction of infrastructure. An example of this would be building provisional storm drains or diversion dams. Emergency response aims to provide immediate help to keep people alive, improve their health and support their morale. It can involve specific but limited aid, such as helping refugees with transport, temporary shelter, and food, or it can involve establishing semi-permanent settlements in camps and other locations. It may also involve initial repairs to damage to infrastructure, or diverting it.

The response phase focuses on keeping people safe, preventing the next disasters and meeting people's basic needs until more permanent and sustainable solutions are available. The governments where the disaster has happened have the main responsibility for addressing these needs. Humanitarian organisations are often present in this phase of the disaster management cycle. This is especially true in places where the government does not have the resources for a full response.

Etymology

The word disaster is derived from Middle French désastre which comes from Old Italian disastro. This in turn comes from the Ancient Greek pejorative prefix δυσ- (dus-) "bad" and ἀστήρ (aster), "star".