Earthflow
A mass movement characterized by downslope translation by flowage of fine surficial materials, such as regolith or soil.

Ecosystem
Basic ecological unit formed by the living environment of the animal and vegetable organisms interacting as a single functional entity.

Elements at risk
Population, buildings and engineering works, infrastructure, environmental features and economic activities in the area affected by a hazard.

Emergency
An imminent or actual event that threatens people, property or the environment and which requires a coordinated and rapid response to minimize its adverse consequences. Emergencies are usually unforeseen and unanticipated, even though they can, and should be planned for. It is implicit that the consequences of ignoring an emergency or not dealing with it properly are avoidable casualties or damage.

Emergency management
(see also civil defence) Short-term measures taken to respond to particular hazards, risks, incidents, or disasters. Resources and manpower pertaining to government, voluntary and private agencies are organized and directed on the basis of a plan that anticipates needs and coordinates efforts by assigning to particular responders, organizations of field units.

Emergency mapping
The cartographic depiction of selected aspects of disaster impact or the subsequent emergency relief effort. As the situation can change rapidly because of increases in the knowledge of damage and casualties, or to developments in the relief effort, there is a certain imperative to emergency mapping. It is therefore best carried out using computers with programs, such as geographical information systems, that produce refresher graphics.

Emergency planning
Planning of actions for the case of a disaster, training of special teams and of population, contingency planning, testing of disaster scenario.

Emergency preparedness plan
Document which contains procedures for dealing with various emergencies which could result from a disaster.

Environmental risks
Risks to natural ecosystems or to the aesthetics, sustainability or amenity of the natural world.

Erosion
Localized removal of rock or soil as a result of the action of water, ice, wind; coastal processes or mass movement.

Evacuation
Precautionary, temporary, planned removal of people or moveable items that, if left in place, would result in avoidable casualties or damage.

Evaluation
(post-disaster) Appraisal of all aspects of the disaster and its effects.

Event
An incident or situation, which occurs in a particular place during a particular interval of time.

Event tree analysis
Inductive analysis process that utilises an event tree graphical construct that shows the logical sequence of the occurrence of events in, or states of, a system following an initiating event.

Exceedance probability
Probability that a given magnitude of an event will be equalled or exceeded.

Expected losses/effects
The expected number of lives lost, persons injured, damage to property and disruption of essential services and economic activity due to the impact of a particular natural or man-made hazard. It includes physical, social/functional and economic effects.

Expected value
The average or central tendency of a random variable. In risk analysis, the product of the probability of an event and of its consequences, aggregated over all possible values of the variable.

Exposure
The length or proportion of time that a person, building or other entity runs a risk. Fixed capital (e.g. houses, bridge, factories) permanently varies the proportion and intensity of exposure. Routine behaviour problems also cause exposure to vary. For example, if the principal risk arises from the collapse of bridges during a landslide, people will be most exposed to it during daily commuting to or from on other forms of regular journey.

Exposure time
The time period of interest for risk calculations, hazard calculations, or design of structures. For structures, the exposure time is often chosen to be equal to the design lifetime of the structure.

Extreme event
Event, which has a very low annual excedance probability (AEP). Sometimes defined as an event beyond the credible limit of extrapolation and therefore dependent on the length of record and the quality of the data available.

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