This section presents a set of selected data and statistics on natural disaster occurrence and their impact for the different periods : 1900-2005, 1970-2005 and 1991-2005. They are all based on the data available at the OFDA/CRED International Disasters Database (EM-DAT). The Centre for Research on the Epidemiology of Disasters (CRED) has arranged and provided such information according to country and thematic aggregations, as requested by the UN/ISDR secretariat. Maintenance of this section will be done jointly with CRED.

Data on disaster occurrence, its effect upon people and its cost to countries, are primary inputs to analyse the temporal and geographical trends in disaster impact. Disasters are tracking points, in time and space, where the most unfavourable combinations of hazard occurrence, physical exposure and vulnerability conditions are revealed. Disaster losses, systematically registered in historical databases, provide the basis for identifying where, and to what extent, the potentially negative outcomes embedded in the concept of risk is realized. They help to understand where, and to whom, disaster risk becomes impact. They also provide the basis for risk assessment processes, a departing point for the application of disaster reduction measures.

The statistics are presented in three main categories: a) disaster occurrence; b) disaster impact and c) top 50 countries for economic damages. The figures presented here should be regarded as indicative. Those who intend to make a more thorough and in-depth statistical analysis of disaster data are encouraged to visit the EM-DAT website (www.em-dat.net). 

CRED defines a disaster as a "situation or event, which overwhelms local capacity, necessitating a request to national or international level for external assistance (definition considered in EM-DAT); an unforeseen and often sudden event that causes great damage, destruction and human suffering". For a disaster to be entered into the database at least one of the following criteria must be fulfilled:

• 10 or more people reported killed
• 100 people reported affected
• Declaration of a state of emergency
• Call for international assistance

The number of people killed includes "persons confirmed as dead and persons missing and presumed dead"; people affected are those "requiring immediate assistance during a period of emergency, i.e. requiring basic survival needs such as food, water, shelter, sanitation and immediate medical assistance (definition considered in EM-DAT)". In the tables, people reported injured or homeless were aggregated with those reported affected to produce a "total number of people affected".

"The economic impact of a disaster usually consists of direct (e.g. damage to infrastructure, crops, housing) and indirect (e.g. loss of revenues, unemployment, market destabilisation) consequences on the local economy". In EM-DAT the registered figure corresponds to the damage value at the moment of the event and only to the direct damage. Amounts of damage are given in 2003 US$.

EMDAT distinguishes two different type of disasters (natural and technological) divided into 15 main categories, covering more than 50 sub-categories.

For the production of the tables and figures, the natural disasters were split into 3 specific groups:

• Hydro-meteorological disasters: including floods and wave surges, storms, droughts and related disasters (extreme temperatures and forest/scrub fires), and landslides & avalanches;
• Geophysical disasters: divided into earthquakes & tsunamis and volcanic eruptions;
• Biological disasters: covering epidemics and insect infestations.

As for famines, which are neither natural nor technological disasters, they have not been considered in this analysis.

The classification of countries in major world aggregates (OECD, CEE & CIS, developing countries and least developed countries) has been based in the country classification presented in the Technical Notes of the Human Development Report 2005 (UNDP).

The classification of countries by their level of income (“High”, “Middle” and “Low”) comes from the World Bank. The classification of countries in major world aggregates (OECD, CEE & CIS, developing countries and least developed countries) has been based in the country classification annex of the Human Development Report 2003 (UNDP).

Geographical distributions are based on United Nations regions and subregions. Population data used for estimations of killed and affected per 1,000,000 inhabitants where extracted from the US Census Bureau International Data Base.

Caveats

Today key problems with disaster data remain the lack of standardised collection methodologies and definitions. The original information, collected from a variety of public sources, is not specifically gathered for statistical purposes. Even when the compilation is based on strict definitions for disaster events and parameters, the original suppliers of information may not follow rigorous criteria. Moreover, data are not always complete for each disaster. The degree of completion may vary according to the type of disaster or its country of occurrence.

Data on deaths are most of the time available because there is an immediate proxy for the severity of the disaster. However, the numbers put forward in the first few moments after a disaster may be significantly revised, even several months later.

Data on the numbers of people affected by a disaster can be very useful for risk assessment, but are often poorly reported. Moreover, the definition of "affected" remains always open to interpretation, political or otherwise. Even in absence of manipulation data can be extrapolated from old census information, with assumptions being made about the percentage of an area's population affected.

Data can also be skewed because of the rationale behind data gathering. Reinsurance companies, for instance, systematically gather data on disaster occurrence in order to assess insurance risk, but with a priority in areas of the world where disaster insurance is widespread. Their data may therefore miss out poor disaster-affected regions where insurance is unaffordable or unavailable.

For natural disasters during the last decade, data on deaths are missing in about 10 per cent of the disasters; around 20 per cent lack information on the total number of people affected, and about 70 per cent do not cover economic damages. The figures therefore should be regarded as indicative. Relative changes and trends are more useful to look at than absolute, isolated figures.

Dates can also be a source of ambiguity. For example, a declared date for a drought is both necessary and meaningless - drought do not occur in a single day. In such cases, the date the appropriate body declares an official emergency has been used.

Changes in national boundaries also cause ambiguities in the data and may make long-term trends analysis more complicated.

Information systems have improved vastly in the last 25 years and statistical data is now more easily available, intensified by an increasing sensitivity to disasters occurrence and consequences. However, despite efforts to verify and review data, the quality of disaster databases can only be as good as the reporting system. The lack of systematisation and standardisation of data collection reveals now its major weakness for long-term planning. Fortunately, due to increased pressures for accountability from various sources, many donors and development agencies have increased their attention on data collection and its methodologies.

For questions or comments on the statistical information presented in this section please contact: