This glossary contains a number of definitions of terms that are used in the CHARIM handbooks, They have been derived from different sources, such as:

• SafeLand, deliverable 2.4, Guidelines for landslide susceptibility, hazard and risk assessment and zoning

Annual Exceedance Probability (AEP) – The estimated probability that an event of specified magnitude will be exceeded in any year.

Consequence – The outcomes or potential outcomes arising from the occurrence of a landslide expressed qualitatively or quantitatively, in terms of loss, disadvantage or gain, damage, injury or loss of life.

Danger – The natural phenomenon that could lead to damage, described in terms of its geometry, mechanical and other characteristics. The danger can be an existing one (such as a creeping slope) or a potential one (such as a rock fall). The characterisation of a danger does not include any forecasting.

Elements_at_risk – The population, buildings and engineering works, economic activities, public services utilities, infrastructure and environmental features in the area potentially affected by landslides.

Environmental risk – (a) The potential for an adverse effect on the natural system (environment). (b) the probability of suffering damage because of exposure to some environmental circumstance. The latter acception will not be used in this document.

Exposure – Exposure is the spatial overlay of a hazard footprint and (set of) elements at risk.People, property, systems, or other elements present in hazard zones that are thereby subject to potential losses(UNISDR,2009).

Frequency – A measure of likelihood expressed as the number of occurrences of an event in a given time. See also Likelihood and Probability.

Hazard – A condition with the potential for causing an undesirable consequence. The description of landslide hazard should include the location, volume (or area), classification and velocity of the potential landslides and any resultant detached material, and the probability of their occurrence within a given period of time.

Hazard zoning – The subdivision of the terrain in zones that are characterized by the temporal probability of occurrence of landslides of a particular size and volume, within a given period of time. Landslide hazard maps should indicate both the zones where landslides may occur as well as the runout zones. A complete quantitative landslide hazard assessment includes:

• spatial probability: the probability that a given area is hit by a landslide
• temporal probability: the probability that a given triggering event will cause landslides
• size/volume probability: probability that the slide has a given size/volume
• runout probability: probability that the slide will reach a certain distance downslope

Individual risk to life – The risk of fatality or injury to any identifiable (named) individual who lives within the zone impacted by the landslide; or who follows a particular pattern of life that might subject him or her to the consequences of the landslide.

Landslide inventory – The collection of landslide features in a certain area for a certain period, preferably in digital form with spatial information related to the location (as points or polygons) combined with attribute information. These attributes should ideally contain information on the type of landslide, date of occurrence or relative age, size and/or volume, current activity, and causes.  Landslide inventories are either continuous in time, or provide so-called event-based landslide inventories, which are inventories of landslides that happened as a result of a particular triggering event (rainfall, earthquake).

Landslide activity – The stage of development of a landslide; pre-failure when the slope is strained throughout but is essentially intact; failure characterized by the formation of a continuous surface of rupture; post-failure which includes movement from just after failure to when it essentially stops; and reactivation when the slope slides along one or several pre-existing surfaces of rupture. Reactivation may be occasional (e.g. seasonal) or continuous (in which case the slide is “active”).

Landslide hazard map - The subdivision of the terrain in zones that are characterized by the temporal probability of occurrence of landslides of a particular size and volume, within a given period of time. Landslide hazard maps should indicate both the zones where landslides may occur as well as the runout zones. A complete quantitative landslide hazard assessment includes:

• Spatial probability: the probability that a given area is hit by a landslide.
• Temporal probability: the probability that a given triggering event will cause landslides
• Volume/intensity probability: probability that the slide has a given volume/intensity
• Runout probability: probability that the slide will reach a certain distance downslope

Landslide intensity – A set of spatially distributed parameters related to the destructive power of a landslide. The parameters may be described quantitatively or qualitatively and may include maximum movement velocity, total displacement, differential displacement, depth of the moving mass, peak discharge per unit width, kinetic energy per unit area.

Landslide magnitude – The measure of the landslide size. It may be quantitatively described by its volume or, indirectly by its area. The latter descriptors may refer to the landslide scar, the landslide deposit or both

Landslide probablity – In the framework of landslide hazard the following types of probability are of importance:

• spatial probability: the probability that a given area is hit by a landslide
• temporal probability: the probability that a given triggering event will cause landslides
• size/volume probability: probability that the slide has a given size/volume
• runout probability: probability that the slide will reach a certain distance downslope

Landslide risk map - The subdivision of the terrain in zones that are characterized by different probabilities of losses (physical, human, economic, environmental) that might occur due to landslides of a given type within a given period of time.  The risk may be indicated either qualitatively (as high, moderate, low and no risk) or quantitatively (in numbers or economic values).  Risk is quantitatively estimated by the product of probability x consequences.  It is usually calculated as:

• On annual basis: i.e. the expected losses in a particular area being struck by a landslide of a given magnitude (intensity) in a given year.
• As a recurrence interval, i.e. the expected losses in a particular area being struck by the 100-year landslide event or
• the cumulative losses during a given time interval due to landslides with different return periods

Landslide susceptibility – A quantitative or qualitative assessment of the classification, volume (or area) and spatial distribution of landslides which exist or potentially may occur in an area. Susceptibility may also include a description of the velocity and intensity of the existing or potential landsliding.

Landslide susceptibility map – A map showing the subdivision of the terrain in zones that have a different likelihood that landslides of a type may occur. The likelihood may be indicated either qualitatively (as high, moderate low, and not susceptible) or quantitatively (e.g. as the density in number per square kilometres, or area affected per square kilometre). Landslide susceptibility maps should indicate both the zones where landslides may occur as well as the runout zones.

Likelihood – Used as a qualitative description of probability or frequency.

Probability – A measure of the degree of certainty. This measure has a value between zero (impossibility) and 1.0 (certainty). It is an estimate of the likelihood of the magnitude of the uncertain quantity, or the likelihood of the occurrence of the uncertain future event.

There are two main interpretations:

• Statistical-frequency or fraction – The outcome of a repetitive experiment of some kind like flipping coins. It includes also the idea of population variability. Such a number is called an “objective” or relative frequentist probability because it exists in the real world and is in principle measurable by doing the experiment.
• Subjective probability (degree of belief) – Quantified measure of belief, judgement, or confidence in the likelihood of a outcome, obtained by considering all available information honestly, fairly, and with a minimum of bias. Subjective probability is affected by the state of understanding of a process, judgement regarding an evaluation, or the quality and quantity of information. It may change over time as the state of knowledge changes.

Qualitative risk analysis – An analysis which uses word form, descriptive or numeric rating scales to describe the magnitude of potential consequences and the likelihood that those consequences will occur.

Quantitative risk analysis – An analysis based on numerical values of the probability, vulnerability and consequences, and resulting in a numerical value of the risk.

Residual risk – the degree of existing risk given the presence of both stabilization and protection measures.

Risk – A measure of the probability and severity of an adverse effect to health, property or the environment. Risk is often estimated by the product of probability × consequences. However, a more general interpretation of risk involves a comparison of the probability and consequences in a non-product form.

Risk analysis – The use of available information to estimate the risk to individuals, population, property, or the environment, from hazards. Risk analyses generally contain the following steps: Scope definition, hazard identification, vulnerability evaluation and risk estimation.

Risk assessment – The process of risk analysis and risk evaluation. In some communities (for instance those dealing with flood) risk assessment differs from risk evaluation by the fact that it includes subjective aspects such as risk perception.

Risk control or risk treatment – The process of decision making for managing risk, and the implementation or enforcement of risk mitigation measures and the reevaluation of its effectiveness from time to time, using the results of risk assessment as one input.

Risk estimation – The process used to produce a measure of the level of health, property, or environmental risks being analysed. Risk estimation contains the following steps: frequency analysis, consequence analysis, and their integration.

Risk evaluation – The stage at which values and judgements enter the decision process, explicitly or implicitly, by including consideration of the importance of the estimated risks and the associated social, environmental, and economic consequences, in order to identify a range of alternatives for managing the risks.

Risk management – The complete process of risk assessment and risk control (or risk treatment).

Risk perception – The way how people/communities/authorities judge the severity of the risk, based on their personal situation, social, political, cultural and religious background, economic level, their level of awareness, the information they have received regarding the risk, and the way they rate the risk in relation with other problems.

Societal risk – The risk of multiple fatalities or injuries in society as a whole: one where society would have to carry the burden of a landslide causing a number of deaths, injuries, financial, environmental, and other losses.

Susceptibility – see Landslide susceptibility.

Temporal–spatial probability of the element at risk – The probability that the element at risk is in the area affected by the landsliding, at the time of the landslide. It is the quantitative expression of the exposure.

Tolerable risk – A risk within a range that society can live with so as to secure certain net benefits. It is a range of risk regarded as non-negligible and needing to be kept under review and reduced further if possible.

Vulnerability – The degree of loss to a given element or set of elements exposed to the occurrence of a landslide of a given magnitude/intensity. It is expressed on a scale of 0 (no loss) to 1 (total loss). For property, the loss will be the value of the damage relative to the value of the property; for persons, it will be the probability that a particular life (the element at risk) will be lost, given the person(s) is affected by the landslide. Vulnerability could also refer to the propensity to loss (or the probability of loss), and not the degree of loss.

Zoning – The division of land into homogeneous areas or domains and their ranking according to degrees of actual or potential landslide susceptibility, hazard or risk