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Risk analysis procedure

The application of the risk model involved the following steps for each hazard type:

1. Compile geographical and physical information on specific hazard events such as tropical cyclone track data, areas of flood extent, or earthquake location and magnitude.

2. For each hazard event, determine the footprint or area of impact, such as the area where a tropical storm exceeded tropical cyclone-force wind speed.

3. For each impact area, compute exposure as the number of people and economic assets within that area. 4. Link available loss information for each hazard event (sourced from EMDAT) to the hazard event information (hazard severity and exposure).

5. Add information on vulnerability. Since global data on direct vulnerability factors such as building quality are unavailable, this analysis uses country-level indicators for the year in which the event occurred, such as government accountability or per capita income.

6. Estimate empirical loss functions that relate event mortality or economic losses to risk factors (hazard characteristics, exposure and vulnerability) using statistical regression techniques.

7. Derive an estimate of expected average annual losses and exposure. The estimated loss functions are used to impute disaster outcomes for all recorded events, whether or not a loss estimate is available in EMDAT or not. This is done using data on exposure and vulnerability for 2007 such that annualized average estimates reflect current conditions.

8. Apply estimates to all pixels in a geographic grid. The loss estimates are aggregated at different levels (1 km x 1 km cells; sub-national administrative areas; countries) allowing the identification of geographic concentrations of risk. Mortality risk is classed in deciles using a logarithmic index with values ranging from 1 = negligible to 10 = extreme risk (see below). Economic loss risk is calculated for World Bank regions and country income groups.

Fast Facts

Cyclones

Bangladesh faces the highest absolute risk and comes second in relative terms. Other countries with high absolute risk include India, Philippines, Myanmar, Madagascar and China. Small Islands Developing States (SIDS) such as Haiti, Fiji and Vanuatu have a high relative risk¹, but because of their small population, a relatively low absolute mortality risk.

Geographically, tropical cyclone mortality risk is highly concentrated. For example, more than 75% of the expected mortality is concentrated in Bangladesh and 10.8% in India.

There are significant differences in risk between different groups of countries. Relative mortality risk is approximately 200 times higher in low-income countries than in Organization for Economic Cooperation and Development (OECD) countries and approximately 30 times greater in low human development countries than in high human development countries.

Each year approximately 78 million people worldwide are exposed to tropical cyclone wind hazard and a further 1.6 million to related storm surge. Asian countries have the largest absolute population exposed in both categories while most SIDS have the highest proportion of their population exposed. SIDS have a far higher relative exposure to highly destructive Category 3 and 4 storms than larger countries, given the exposure of most of their territory.

Flood

Mortality from flood events is closely associated to the size and growth rate of exposed rural populations. It is heavily concentrated in Asia, especially in India, Bangladesh and China. These countries account for 75% of the world's mortality risk for floods.

Relative to tropical cyclones, flood damages are less concentrated across countries. Highincome countries (especially the United States and Germany) account for the largest share of average annual modelled damages. China, Indonesia and Thailand together account for 25%. By far the largest damages in relation to the size of economies occur in South Asia, followed by sub-Saharan Africa and East Asia.

The ratio of losses to gross domestic product (GDP) exposure in high-income countries is far higher than in Latin America and the Caribbean or South Asia. This probably indicates the differential impact of flooding on primary sector activities, such as raising livestock and other forms of agriculture and fishing, in the latter two regions, compared to the impact on industry and services in the high-income countries.

The top 10 most exposed countries - in absolute and relative terms - are in South and South-East Asia, which are home to a number of heavily populated river deltas and watersheds. GDP exposure is also heavilyconcentrated in Asia. However, developed countries, such as the United States of America, Germany, Japan and France also have high absolute GDP exposure, while African countries, such as Benin, Sudan and Chad have high relative GDP exposure.

In the case of economic risk, smaller, more concentrated floods appear to cause relatively greater economic damages than floods covering a larger area.

Landslide

Compared to other hazards, global landslide mortality risk is relatively low. The predicted mortality risk even in very large countries such as India or China is less than 100 deaths per year. Absolute mortality risk is highest in countries such as Ethiopia, Indonesia and India. Relative mortality risk is highest in small islands, notably in Comoros. Approximately 55% of mortality risk is concentrated in 10 countries, which also account for 80% of exposure.

Some 2.2 million people annually are exposed worldwide to landslides. In absolute terms, exposure is very high in a number of large Asian countries, especially,India, Indonesia and China. Relative exposure is highest in small countries with steep terrain including a number of small island nations. The relative importance of the triggering mechanism varies widely among countries.

Drought

Drought differs from other hazard types in the way losses are incurred. Few droughts lead directly to mortality. Those that do have generally occurred during a political crisis or civil conflict where aid could not reach the affected population. In these cases the mortality should more properly be attributed to the conflict than to the drought. Impacts might also be highest even after the meteorological drought event has ended, for instance when people have exhausted their food supplies long before the next harvest.

Relative to their population and cultivated area, sub-Saharan African countries have the most people and crops exposed to drought.

Earthquake

China, India and Indonesia are the countries with the highest absolute mortality risk, while some smaller countries, such as El Salvador and Guatemala have very high relative risk. Some countries, such as the Democratic Republic of Congo, that have not experienced recent major earthquake disasters have high levels of both absolute and relative mortality risk.

Altogether, 97% of mortality risk is concentrated in low- and lower middle-income countries (11.7% and 85.3% respectively). The upper middle and high-income countries concentrate 2.6% of the risk (1.7% and 0.9% respectively).

Mortality risk is highly concentrated for seismic risk. It is estimated that 86% of mortality risk is attributable to disasters with more than 10,000 fatalities. This is consistent with the observed losses. Of the 250,000 deaths from earthquakes over the last 10 years², about 92% resulted from five mega-disasters³.

¹: Relative risk refers to the number of people killed as compared to total population, or economic loss as a share of national GDP.
²: As reported by CRED/EMDAT for earthquakes between 1975 and 2008.
³: Izmit (Turkey, 1999, 17,000 killed); Bhuj (Gujarat, India, 2001, 20,000 deaths); Bam (Iran, 2003, 26,800 deaths); Jammu/Kashmir (Pakistan/India, 2005, 74,000 killed) and Sishuan (China, 2008, 87,900 deaths).