Global Assessment Report on Disaster Risk Reduction 2015
Making development sustainable: The future of disaster risk management

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GAR15 uses a set of terms and definitions that build on those included in the previous three GAR.
Disaster risk is considered to be a function of hazard, exposure and vulnerability. Disaster risk is normally expressed as the probability of loss of life, injury or destroyed or damaged capital stock in a given period of time. Generic definitions of these and other terms are available in the UNISDR Glossary. i The way these terms are used in GAR15 is explained below.
GAR15 uses the term physical (rather than natural) hazard to refer to hazardous phenomena such as floods, storms, droughts and earthquakes. Processes such as urbanization, environmental degradation and climate change shape and configure hazards; therefore, it is becoming increasingly difficult to disentangle their natural and human attributes. Exposure is used to refer to the location of people, production, infrastructure, housing and other tangible human assets in hazard-prone areas. Vulnerability is used to refer to the susceptibility of these assets to suffer damage and loss due to socially constructed factors that result in unsafe and insecure conditions in the built and human environments. Resilience is used to refer to the capacity of systems (ranging from national, local or household economies to businesses and their supply chains) to anticipate, absorb or buffer losses, and to recover.
Extensive risk is used to describe the risk of low-severity, high-frequency disasters, mainly but not exclusively associated with highly localized hazards. Intensive risk is used to describe the risk of high-severity, mid to low-frequency disasters, mainly associated with major hazards. Emerging risk is used to describe the risk of extremely low-probability
disasters associated with new patterns of hazard and vulnerability. Geomagnetic storms, for example, have always occurred, but the associated risks are now magnified by the growing dependence of modern societies on vulnerable energy and telecommunications networks. Underlying risk drivers are processes such as badly planned and managed urban and regional development, environmental degradation, poverty, climate change and weak governance, which directly shape risk patterns and trends. Risk inequality is used to describe the uneven social, economic and territorial distribution of disaster risk.
Direct disaster losses refer to damage to human lives, buildings, infrastructure and natural resources. Economic direct losses are calculated using proxies for replacement costs. Indirect disaster losses are declines in output or revenue, as a consequence of direct losses or owing to impacts on a supply chain. Wider impacts include longer-terms social and economic effects, for example in education, health, productivity or in the macro economy.
The Global Risk Assessment uses a probabilistic approach. Probability is defined as the likelihood of a loss occurring compared to all the possible losses that might occur. The exceedance probability is the likelihood of a loss of a given magnitude occurring or being exceeded within a defined time span. Frequency is the expected number of times that a particular loss occurs in a defined time span. Return period is the average frequency with which a particular loss is expected to occur. It is usually expressed in years, such as 1 in X number of years. This does not mean that a loss will occur once every X numbers of years, but rather that it will occur once on average every X number of years.
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