Glossary of concepts and terminology
Note: The number in square brackets following each definition refers to the list of references at the end of the glossary.
4R's: Means (a) reduction, (b) readiness, (c) response, and (d) recovery (emergency management). [9]
acceptable risk: The level of risk that a society or community considers acceptable given existing social, economic, political, cultural, technical and environmental conditions. In engineering terms, acceptable risk is also used to assess structural and non-structural measures undertaken to reduce possible damage at a level which does not harm people and property, according to codes or "accepted practice" based, among other issues, on a known probability of hazard. [4]
advisory: A message to say that a hazard is in the early stages of approaching, and warnings may follow. [1]
aftershock: A smaller earthquake that follows the main shock and originates close to the focus of the main shock. Aftershocks generally decrease in number and magnitude over time. [5]
alarm: A visible or audible signal giving warning of danger. [7]
alert: Advisory that hazard is approaching and that places emergency forces on stand-by, pending mobilization, but is less imminent than implied by a warning message. See warning. [7]
all-hazards planning: Most hazardous places are threatened by more than one set of hazards and associated risks. Besides the presence of several classes of extreme phenomena, there may be secondary hazards (e.g. earthquake-induced landslides). It is often more efficient to plan for all the major hazards to be expected in a region rather than separately for single ones. This allows economies of scale to be achieved and risks to be tackled comprehensively. [1]
ash flow: Pyroclastic flow including a liquid phase and a solid phase composed mainly of ash. [5]
avalanche: The rapid and sudden sliding and flowage of masses of usually incoherent and unsorted material such as snow/ice/rock or mixtures of these materials. [5]
background levels (of risk): In risk analysis, inherent natural or normal levels of risk in addition to risk from any specific factor. [1]
biological hazard: Processes of organic origin or those conveyed by biological vectors, including exposure to pathogenic micro-organisms, toxins and bioactive substances, which may cause the loss of life or injury, property damage, social and economic disruption or environmental degradation.
Examples of biological hazards include outbreaks of epidemic diseases, plant or animal contagion, insect plagues and extensive infestations. [4]
building codes: Regulations or ordinances for controlling the design, construction, materials, alteration and occupancy of any structure to insure human safety and welfare. Building codes include both technical and functional standards. [4]
capacity: A combination of all the strengths and resources available within a community, society or organisation that can reduce the level of risk, or the effects of a disaster. Capacity may include physical, institutional, social or economic means as well as skilled personal or collective attributes such as leadership and management. Capacity may also be described as capability. [4]
capacity building: Efforts aimed to develop human skills or societal infrastructures within a community or organisation needed to reduce the level of risk. [7]
In extended understanding, capacity building also includes development of institutional, financial, political and other resources, such as technology at different levels and sectors of the society.
casualty: A person killed or injured in an event. Injury can be divided into physical trauma (e.g. fractured bones) and psychological trauma (e.g. post-traumatic stress disorder). [1]
catastrophe: The terms disaster and catastrophe can be used synonymously because definitions of the two terms are not sufficiently well developed, precise or subject to consensus, that the terms can rigorously be distinguished from one another. However some authors regard a catastrophe to be more cataclysmic than a disaster and to affect a larger area. Jurisdictions affected by catastrophe, or so it is argued, are more thoroughly overwhelmed by it that they would be in the case of a disaster. [1]
CDEM: Civil Defence Emergency Management. Means the application of measures, knowledge, and practices that: are necessary or desirable for the safety of the public or property; and are designed to guard against, prevent, reduce, or overcome any hazard or the harm or loss that may be associated with any emergency. Includes, without limitation, the planning, organisation, coordination, and implementation of such measures, knowledge, and practices. [10]
CDEM Groups: Consortia of local authorities working in partnership with emergency services, major utilities and others to ensure that emergency management principles are applied at the local level. [10]
CIMS:Coordinated Incident Management System (emergency management). [9]
civil defence: The process of protecting the general public, organisations, institutions, commerce and industry against disaster, by creating an operational structure for mitigation, readiness, response and recovery. Military forces do not play a central role in civil protection, which is in the hands of administrative authorities, such as municipal, provincial, state or national governments. [1]
climate change: The climate of a place or region is changed if over an extended period (typically decades or longer) there is a statistically significant change in measurements of either the mean state or variability of the climate for that place or region. Changes in climate may be due to natural processes or to persistent anthropogenic changes in atmosphere or in land use. [4]
consequence: The outcome of an event expressed qualitatively or quantitatively, being a loss, injury, disadvantage or gain. There may be a range of possible outcomes associated with an event. [2]
consequence analysis: Identifying the type of impact or loss expected from a given hazard or hazards by determining the elements at risk and their vulnerability. [2]
coping capacity: The means by which people or organisations use available resources and abilities to face adverse consequences that could lead to a disaster. In general, this involves managing resources, both in normal times as well as during crises or adverse conditions. The strengthening of coping capacities usually builds resilience to withstand the effects of natural and human-induced hazards. [4]
cost effectiveness: A measure of efficacy obtained by quantifying the costs and benefits of an activity and comparing them in a cost-benefit ratio. Cost effectiveness does not necessarily require a predominance of benefits over costs, nor can all benefits always be quantified as readily as costs can. [1]
cost (of event, situation or activities): The negative impacts which may extend beyond damage and losses and may or may not be quantifiable, both direct and indirect, including damage, time, labour, disruption, goodwill, political and intangible losses. Whereas losses refer to negative effects to existing resources, costs refer to adverse effects that go beyond existing use. [2]
cost-benefit analysis: Assessment and comparison of the costs and benefits associated with an activity or proposed activity. For example, a comparison of the costs of establishing slope stability measures compared to the accrued economic benefits of being able to occupy that place as a result of the achieved reduction of landslide risk. [7]
counter measures (syn. treatments): All measures taken to counter and reduce disaster risk. They most commonly refer to engineering (structural) measures but can also include non-structural measures and tools designed and employed to avoid or limit the adverse impact of natural hazards and related environmental and technological disasters. [4]
crisis: In disasters, a point at which normal mechanisms for coping (personal, organisational or institutional) suddenly cease to function as a result of the seriousness of the impact. [1]
cyclone: A large-scale closed circulation system in the atmosphere with low barometric pressure and strong winds that rotate counter clockwise in the northern hemisphere and clockwise in the southern hemisphere. [6]
damage assessment: Investigation of damaged property and quantification of the value of losses. Monetary estimates usually depend on the cost of repairing the damage, which in turn depends on the adoption of particular techniques and components whose values are known. [1]
damage ratio: The cost of damage expressed as a ratio of the total value of the object damaged in an event. When referred to a given magnitude of event, this ratio represents vulnerability. [7]
debris flow: A high-density, rapid, downslope flowage of surfical slope-forming material with abundant coarse-grained materials such as rocks and tree trunks. [5]
disaster: A serious disruption of the functioning of a community or a society causing widespread human, material, economic or environmental losses which exceed the ability of the affected community or society to cope using its own resources. A disaster is a function of the risk process. It results from the combination of hazards, conditions of vulnerability and insufficient capacity or measures to reduce the potential negative consequences of risk. [4]
disaster insurance: Government sponsored or private insurance policies for protection against economic losses resulting from disaster. Such insurance can also apply to individual property loss in the case of specified hazards e.g. the Earthquake Commission New Zealand (EQC). [7]
disaster response: A sum of decisions and actions taken during and after disaster, including immediate relief, rehabilitation, and reconstruction. [5]
displaced persons: Persons who, for different reasons or circumstances, have been compelled to leave their homes. [7]
early warning: The provision of timely and effective information, through identified institutions, that allows individuals exposed to a hazard to take action to avoid or reduce their risk and prepare for effective response. Early warning systems include a chain of concerns, namely: understanding and mapping the hazard; monitoring and forecasting impending events; processing and disseminating understandable warnings to political authorities and the population; and undertaking appropriate and timely actions in response to the warnings. [4]
earth flow: A mass movement characterized by down slope translation by flowage of fine surficial material, such as regolith and soil. [5]
earthquake: The energy release from a sudden break within the upper layers of the earth, sometimes breaking the surface, resulting in the vibration of the ground, which where strong enough will cause the collapse of buildings and destruction of life and property. [5]
earthquake intensity: A measure of the perceived shaking effects of earthquakes and of the damage they cause to the built and natural environments. A variety of scales are used throughout the world - in New Zealand the most common scale is the Modified Mercalli (MM) scale, which has been referenced to New Zealand conditions. [1]
earthquake magnitude: A standardized measure of the size of the largest seismic waves created by the movement of a geological fault in the earth's brittle crust. Charles Richter's 1935 magnitude scale (the Richter Scale) is now known as local magnitude (ML), and is used in conjunction with other scales such as those for the body waves (MB) and surface waves (MS). As the scales are logarithmic, earthquakes with high magnitude are very much larger than those with moderate or small magnitude. Seismic magnitude is an indirect measure of the amount of physical energy released by an earthquake. [1]
earthquake swarm: A series of minor earth tremors (none of which may be identified as the main shock) that occurs within a limited area and time. [5]
El Niņo Southern Oscillation (ENSO): A complex interaction of the tropical Pacific Ocean and the global atmosphere that results in irregularly occurring episodes of changed ocean and weather patterns in many parts of the world, often with significant impacts, such as altered marine habitats, rainfall changes, floods, droughts, and changes in storm patterns. The El Niņo part of ENSO refers to the well-above-average ocean temperatures along the coasts of Ecuador, Peru and northern Chile and across the eastern equatorial Pacific Ocean, while the Southern Oscillation refers to the associated global patterns of changed atmospheric pressure and rainfall. La Niņa is approximately the opposite condition to El Niņo. Each El Niņo or La Niņa episode usually lasts for several seasons. [4]
elements at risk: The people, buildings and structures, infrastructure, economic activities, public services, or any other defined values exposed to hazards in a given area. [7]
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. [7]
emergency management: The organisation and management of resources and responsibilities for dealing with all aspects of emergencies, in particularly readiness, response and rehabilitation.
Emergency management involves plans, structures and arrangements established to engage the normal endeavours of government, voluntary and private agencies in a comprehensive and coordinated way to respond to the whole spectrum of emergency needs. This is also known as disaster management. See also civil defence.[4]
emergency planning: Planning of actions for the case of a disaster, training of special teams and of population, contingency planning, testing of disaster scenarios. [4]
EOC: Emergency Operations Centre. [9]
epicentre (earthquake): The point on the earth's surface directly above the place of origin (i.e., focus or hypocentre) of an earthquake. [5]
EQC: Earthquake Commission. [9]
erosion: Localised removal of rock or soil as a result of the action of water, ice, wind, coastal processes, or mass movement. [7]
evacuation: Precautionary, temporary, planned removal of people or moveable items that, if left in place, would result in avoidable casualties or damage. [1]
exceedance probability: Probability that a given magnitude of an event will be equalled or exceeded. [5]
exposure: The length or proportion of time that a person, building or other entity runs a risk. Fixed capital (e.g. houses, bridges, 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 earthquakes, people will be most exposed to it during daily commuting to or from work or on other forms of regular journey. [1]
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. [5]
externalization of risk: The process by which risk is divested by or shifted from an individual to other parties. See also internalization of risk. [7]
fault: A planar or gently curved fracture in the earth's upper layers across which displacement occurs. When this displacement is abrupt it gives rise to an earthquake. [5]
focal depth: Vertical distance from the earth's surface to the place of origin (hypocentre, focus) of an earthquake. [5]
focus (earthquake): The point beneath the earth's surface where an earthquake rupture starts and from which waves radiate. [5]
foreshock: Earthquake which is often part of a distinctive sequence which precedes and originates close to the focus of a large earthquake (main shock). [5]
frequency: With respect to natural hazards, the number of events of a given or minimum size per unit time (e.g. the number of earthquakes of magnitude greater than 5.9 per 100 years). The reciprocal of frequency is period.[1]
geological hazard: Natural earth-related processes or phenomena that can cause damage. These may include internal earth processes (tectonic) such as earthquakes, fault rupture, and volcanic activity, or external processes and situations such as landslides and weak foundation soil. [4]
Geographical Information System (GIS): Combined relational databases with spatial interpretation and outputs often in form of maps. A more elaborate definition is that of computer programmes for capturing, storing, checking, integrating, analysing and displaying data about the earth that is spatially referenced. Geographical information systems are increasingly being utilised for hazard and vulnerability mapping and analysis, as well as for the application of disaster risk management measures. [4]
GeoNet: The GeoNet system is a New Zealand national geological hazards monitoring and data collection system, operated by GNZ Science. [9]
ground motion: Seismic vibration of the ground at a particular point, recorded by accelerograph or seismograph in order to determine the vibrational characteristics of an earthquake or explosion. [5]
groundwater level: The level at which soil and porous rock begins to be saturated with water. Usually measured as a depth below the ground surface or as a depth above a defined level, such as a shear surface. [5]
hazard: The actual or potential interaction between extreme natural events and human activities that may result in damage, disruption, death or injury.
In natural hazard usage, there are two accepted definitions of 'hazard'. The first (Hazard I) refers to an actual physical entity (process or situation) that has the potential to cause damage (e.g., a large rockslide or a large earthquake). This is the common non-technical understanding of hazard. However, this use of the term hazard is also found in some legal and statutory documents, with statements of the form: 'It is council policy to record the date and location of hazards. These include, landslide, debris flow, surface flooding, and subsidence ...'. The second definition (Hazard II) is more technical and refers not to a process but rather a threatening condition resulting from the behaviour of that process, expressed as the probability of occurrence of a damaging landslide. [7]
hazard I: A hazard is a potentially damaging process or situation, e.g. an earthquake above a certain intensity or a landslide of sufficient size, depth, or displacement to cause damage or disruption or, as an example of a situation, the presence of weak foundation material. Hazards can include latent conditions that may represent future threats and can have different origins: natural (geological, hydrometeorological, and biological) or induced by human processes (environmental degradation and technological hazards). Hazards can be single, sequential or combined in their origin and effects. Each hazard is characterised by its location, intensity, frequency and probability. See also RMA definition under 'natural hazard' (RMA Part I).
hazard II: The probability of a potentially damaging event occurring in a unit of time. This probability varies with the magnitude of the event (generally small events occur more frequently than large events). Consequently hazard is often expressed as the probability of occurrence of a given magnitude of event. Defined in this way, hazard represents a state or condition and is assessed and applied to a particular place, e.g. site, unit area of land surface, region or object, e.g. lifelines and hydro dams.
hazard analysis: The in-depth study and monitoring of hazards to determine their potential, origin, impact characteristics and behaviour, including their magnitude-frequency behaviour, historic performance and initiating (triggering) factors. [2]
hazard identification: The process of recognising and accounting for all possible hazards that might occur within the place and time period of interest. The process needs to consider the types of element at risk as well as the relationship in time and space between the hazard occurrence and elements at risk. [2]
hazard impact characteristics: Characteristics of the hazard that control the potential impact including: magnitude, duration, areal extent, and speed of onset. [7]
hydrometeorological hazards: Natural processes or phenomena of atmospheric, hydrological or oceanographic nature, which may cause the loss of life or injury, property damage, social and economic disruption or environmental degradation. Hydrometeorological hazards include: floods; hyperconcentrated floods (but not debris flows); tropical cyclones; storm surges; thunder / hailstorms; rain and wind storms; blizzards and other severe storms; drought; desertification; lightning-induced fires; temperature extremes; sand or dust storms; permafrost; and snow or ice avalanches. Hydrometeorological hazards can be single, sequential or combined in their origin and effects. [4]
hypocentre (earthquake): The place inside the earth where the faulting which is associated with the earthquake originated. [5]
incidence: The number of specified occurrences in a given place in a period of time. [7]
incident: In emergency management terms, a sudden event, usually resulting in an emergency, that requires a response from one or more agencies. Incidents are more restricted in scope and consequences than are disasters. [1]
individual risk: Total risk (see societal risk) divided by the population at risk. For example, if a region with a population of one million people experiences on average 5 deaths from landslides per year, the individual risk of being killed, in a year, by a landslide in that region, is 5/1,000,000 usually expressed in orders of magnitude as 5 x 10-6. [7]
initiating factors: See triggering factors.
Interdecadel Pacific Oscillation (IPO): A weather pattern with a 10 to 30 year cycle, operating across the Pacific Ocean.
internalization of risk: The process by which responsibility for risk is borne or assumed by the individual. See also externalization of risk. [7]
involuntary risk: A risk that is borne because there is no reasonable alternative, and because the bearer is unable or reluctant to forgo the benefits associated with tasking the risk. [1]
La Niņa: See El Niņo Southern Oscillation.
lahar: A term originating in Indonesia, designating a debris flow or mud flow over the flank of a volcano and composed of water and volcanic deposits. Primary lahars occur during, or as a result of, eruptions. Secondary lahars have other causes (e.g. the collapse of a crater wall and sudden drainage of a crater lake). [7]
land-use planning: Branch of physical and socio-economic planning that determines the means, and assesses the values or limitations of, various options in which land is to be utilized, with the corresponding effects on different segments of the population or interests of a community taken into account in resulting decisions.
Land-use planning involves studies and mapping, analysis of environmental and hazard data, formulation of alternative land-use decisions and design of a long-range plan for different geographical and administrative scales.
Land-use planning can help to mitigate disasters and reduce risks by discouraging high-density settlements and construction of key installations in hazard-prone areas, control of population density and expansion, and in the siting of service routes for transport, power, water, sewage and other critical facilities. [4]
landslides: Landslides are parts of slopes that break away and move downwards under the influence of gravity. They range in size from mountain slope failures to small roadside collapse. They can creep slowly or move at velocities of several kilometres an hour. They can move with a range of conditions from solid blocks to wet slurries. [7]
landslide stabilization: Measures to prevent movement and increase the stability of a pre-existing landslide. [5]
land-use control: A process used in urban and regional planning, that imposes restrictions and interdictions on the uses to which particular plots of land are put. It is one of the principal instruments of non-structural mitigation, because it can be used to prevent development, or require structural mitigation, at sites where there is a demonstrably strong risk of damage and casualties. However, it is often less effective where development has already taken place. [1]
lava flow: Molten rock which flows down-slope from a volcanic vent, typically moving at between a few metres to several tens of kilometres per hour. [5]
lead time: Period of a particular hazard between its announcement and arrival, also used for the mobilization of resources needed in relief operations. [5]
levee (syn. bund, dike, embankment, stopbank): Water-retaining earthwork used to confine streamflow within a specified area along the stream or to prevent flooding due to waves or tides; or a natural embankment formed by deposition alongside a stream or debris flow pathway. [7]
LGA: Local Government Act 2002
lifelines: Vital communications and essential services that are liable to be compromised in disaster. They include the transportation networks along which emergency vehicles and evacuees will travel, main utility corridors for the distribution of electricity and water, and the medical-assistance infrastructure. [7]
likelihood: Used as a qualitative description of probability or frequency. [2]
liquefaction: Loss of resistance to shear stress of a water-saturated, silty-sandy soil as a consequence of earth shaking, to the extent that the ground behaves as a liquid rather than a solid. [5]
loss: Any negative consequence, financial or otherwise; a reduction in the value of pre-existing resources (part of the costs experienced as the result of a hazard occurrence. See costs. [2]
main shock: The biggest of a particular sequence of earthquakes. [5]
mass movement: A general term for the outward and downward movement of slope forming material under the influence of gravity. Mass movement includes abrupt movements such as landslides, as well as slower, more widespread movements such as creep, and subsidence. [7]
MCDEM: Ministry of Civil Defence and Emergency Management. The agency in central government that coordinates the civil defence emergency management necessary during states of national emergency or civil defence emergencies of national significance. [9]
mean return period: The average time between occurrences of a particular hazardous event. [5]
Mercalli Scale: A10-degree scale that measures earthquake intensity by examining its effects on the Earth's surface, humans, objects of nature, and man-made structures. Mercalli, an Italian seismologist, developed the scale in the early 20th century. Since that time it has been modified several times, and is known today as the Modified Mercalli Scale.
meteorological hazards: See hydrometeorological hazards.
Modified Mercalli (MM) scale: See also Mercalli Scale. A 12-point scale (ranging from I:Instrumental to XII:Catastrophic) that represents the intensity of ground-shaking, or destructiveness, of an earthquake (i.e. the effects of an earthquake, rather than the magnitude). In this way, it differs from the Richter scale which measures the magnitude of an earthquake. There may be many intensities recorded from one earthquake, due to the effects varying from location to location.
The original Mercalli Scale was modified to suit building standards in California. New Zealand scientists have modified it further to suit New Zealand conditions. It is used by scientists, engineers, architects, planners, and insurance companies who need to know the relationship between the strength of shaking at ground level and the degree of damage.
The following outlines the categories on the scale:
I. Instrumental. Not felt except by a very few under especially favourable conditions.
II. Feeble. Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing.
III. Slight. Felt quite noticeably by persons indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.
IV. Moderate. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. Dishes and windows rattle.
V. Rather Strong. Felt by nearly everyone; many awakened. Some dishes and windows broken. Unstable objects overturned. Clocks may stop.
VI. Strong. Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight.
VII. Very Strong. Difficult to stand; furniture broken; damage negligible in building of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving motor cars.
VIII. Destructive. Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved.
IX. Ruinous. General panic; damage considerable in specially designed structures, well designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.
X. Disastrous. Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent.
XI. Very Disastrous. Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly.
XII. Catastrophic. Total damage - Almost everything is destroyed. Lines of sight and level distorted. Objects thrown into the air. The ground moves in waves or ripples. Large amounts of rock may move.
mitigation: Medium-to long-term measures taken in advance of a disaster aimed at decreasing or eliminating its impact on society and environment. Methods are divided into structural mitigation (e.g. building levees along a river to reduce flooding), semi-structural (e.g. allowing floodable areas to exist along a river flood-plain in order to contain flood waves) and non-structural (e.g. flood-damage insurance). Most modern mitigation strategies involve combinations of methods. Mitigation after the event is referred to as alleviation. [7]
mudflow: The rapid and localised down-slope transfer of fine earth material mixed with water. [5]
natural disaster: The impact of an extreme natural phenomenon on the human system (lives, livelihoods and activities). For disaster to occur, the impact must exceed the ability of the human system to absorb or reflect it without suffering considerable, albeit temporary, disruption and losses. [1]
natural hazard: A hazard resulting form natural processes (see hazard). Natural hazards can be classified by origin namely: geological, hydrometeorological or biological. Natural hazards can be dynamic (events) or static (deposits of quick clay). Hazardous events can vary in magnitude or intensity, frequency, duration, area of extent, speed of onset, spatial dispersion and temporal spacing. [4]
As defined in the RMA, means any atmospheric or earth or water related occurrence (including earthquake, tsunami, erosion, volcanic and geothermal activity, landslip, subsidence, sedimentation, wind, drought, fire, or flooding) the action of which adversely affects or may adversely affect human life, property, or other aspects of the environment. [8]
non-structural elements: Those parts of a building (e.g. partitions and ceilings) which do not belong to the load-bearing system. [5]
non-governmental organisation (NGO): Non-profit making organisation operating at the local, national or international levels. Distinct from a governmental organisation, having no statutory ties with a national government. [6]
N-year event (see also return period): Magnitude of an event, the mean return period of which is N years. [5]
period: The average interval between hazard events of a given size.
planning map: A map (often in the form of a statutory district plan) on which prescribed or suggested land uses or planned processes are shown. It serves a prescriptive, rather than a representative, function. [1]
plate tectonics: The dynamics and associated forms resulting from the earth's upper layers being made up of several mobile large rigid plates whose boundaries are fault zones along which slippage takes place.[5]
population at risk: A well-defined population whose lives, property, and livelihoods are threatened by given hazards. [7]
prediction: A statement to the effect that a particular impact will occur in a particular area, with a particular magnitude and set of effects, during a particular time interval. Predictions are the responsibility of bona fide scientists and are usually given in probabilistic terms. A prediction is not as definitive as a forecast. [7]
preparedness: See readiness.
prevention: Encompasses activities designed to provide permanent protection from disasters. It includes engineering and other physical protective measures, and also legislative measures controlling land use and urban planning. [5]
probability: The likelihood of a specific event or outcome, measured by the ratio of specific events or outcomes to the total number of possible events or outcomes. Probability is expressed as a number between 0 and 1, with 0 indicating an impossible event or outcome and 1 indicating an event or outcome is certain. [2]
PTWC: Pacific Tsunami Warning Centre. [9]
PTWC tsunami bulletin: A 'heads up' message giving information on earthquakes of magnitude >6.5 and <7.5 in the Pacific. No destructive threat, no tsunami warning. Investigation under way.[9]
PTWC tsunami watch: A message about earthquakes of magnitude >7.5 in the Pacific, using only seismic information to alert recipients of the probability of a tsunami and that a tsunami investigation is underway. [9]
PTWC tsunami warning: A message about earthquakes of magnitude >7.5 in the Pacific to warn recipients after confirmation has been received that a potentially destructive tsunami has been generated, or when confirmation has not been established but the tsunami travel time to the particular member country is less than 3 hours. [9]
pyroclastic fall: A uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff.
pyroclastic flow: High density flow of solid volcanic fragments suspended in gas which flows downslope from a volcanic vent (at speeds up to 200 km/h) which may also develop from partial collapse of a vertical eruption cone, subdivided according to fragment composition and nature of flowage into: ash flow, glowing avalanche, nuee ardente, pumice flow. [5]
qualitative approach: A method by which information is analysed and evaluated verbally, with argument based on judgement and logic. [7]
quantitative approach: A method by which information is recorded, analysed, and evaluated using numerical scales and techniques. [7]
readiness: Developing operational systems and capabilities before an emergency happens. These include self-help and response programmes for the general public, as well as specific programmes for emergency services, utilities and other agencies. [10]
Activities and measures taken in advance to ensure effective response to the impact of hazards, including the issuance of timely and effective early warnings and the temporary evacuation of people and property from threatened locations. [4]
recovery: Activities beginning after initial impact has been stabilised and extending until the community's capacity for self-help has been restored. [10]
recurrence interval: See return period.
reduction: Identifying and analysing long-term risks to human life and property from natural or man-made hazards; taking steps to eliminate these risks where practicable, and where not, reducing the likelihood and the magnitude of their impact. [10]
release: In risk analysis, the rate at which a hazard strikes, which is usually expressed in terms of frequency and return period, or with respect to the trend of cumulative impacts. [1]
relief: Assistance and/or intervention during or after disaster to meet the life preservation and basic subsistence needs. It can be of emergency or protracted duration. [5]
residual risk: The remaining level of risk after risk treatment measures have been taken. [2]
response: Actions taken immediately before, during or directly after an emergency, to save lives and property, as well as help communities to recover. [10]
retrofitting: Reinforcement of structures to become more resistant and resilient to the forces of natural hazards. [4]
return period (or recurrence interval ): The average time interval between occurrences of a natural hazard event of a given or greater magnitude, usually expressed in years.
Richter scale (Richter magnitude scale): The commonly used scale for measuring the size, or magnitude, of an earthquake. It is a base-10 logarithmic scale obtained by calculating the logarithm of the combined horizontal amplitude of the largest displacement from zero on a seismometer output. Developed in 1935 by Charles Richter in collaboration with Beno Gutenberg, both of the California Institute of Technology, the scale was originally intended to be used only in a particular study area in California, and on seismograms recorded on a particular instrument, the Wood-Anderson torsion seismometer. Richter arbitrarily chose a magnitude 0 event to be an earthquake that would show a maximum combined horizontal displacement of 1 micrometre on a seismogram recorded using a Wood-Anderson torsion seismometer 100 km from the earthquake epicentre. This choice was intended to prevent negative magnitudes from being assigned. However, the Richter scale has no upper or lower limit, and sensitive modern seismographs now routinely record quakes with negative magnitudes. [11]
The following provides a description of the various scale categories: [12]
Less than 3.5: Generally not felt, but recorded.
3.5-5.4: Often felt, but rarely causes damage.
Under 6.0: At most slight damage to well-designed buildings. Can cause major damage to poorly constructed buildings over small regions.
6.1-6.9: Can be destructive in areas up to about 100 kilometres across where people live.
7.0-7.9: Major earthquake. Can cause serious damage over larger areas.
8 or greater: Great earthquake. Can cause serious damage in areas several hundred kilometres across.
risk: Expected losses (e.g. to life, well-being, property, and / or economic activity) due to the occurrence of a natural hazard(s).
Risk is the product of hazard, the value of elements at risk, and vulnerability. [2]
risk acceptance: An informed decision to accept the consequences and the likelihood of a particular risk. [2]
risk analysis: The initial stage of risk assessment involving scope identification, hazard and risk identification, and risk estimation. [7]
risk assessment: Assessing the risk associated with natural hazards using the processes of risk analysis and risk evaluation. [7]
risk avoidance: An informed decision not to become involved in a risk situation. [2]
risk / benefit analysis: In terms of disasters, the benefits of inhabiting areas at risk, of carrying out various activities in them and of putting oneself at risk, set off against the costs of damage and losses in disaster ( including estimated future costs of the event) and of mitigation works. [1]
risk calculation: Risk is calculated by combining hazard analysis and consequence analysis, i.e. a process to determine consequences x frequency. Calculation is generally based on the product of hazard, the value of elements at risk and their vulnerability. In quantitative terms risk is expressed as the probability of adverse effects, per unit of time, for a place, object, or activity. In qualitative terms the risk is expressed as a likelihood, rather than a probability. [7]
risk communication: The communication of information about particular risks to the public (individuals, groups, organisations, institutions) and monitoring of the public's response. [1]
risk control: See risk treatment.
risk engineering: The application of engineering principles and methods to risk management. [2]
risk estimation: Estimating the risk associated with natural hazards using the processes of consequence analysis, hazard analysis and risk calculation. [7]
risk evaluation: Determining the importance and relevance (significance) of the results of calculated or estimated risk with reference to the social and physical context within which they occur. This process determines whether risk is, intolerable, tolerable or acceptable. Risk evaluation may involve considerations of risk perception, risk communication, risk comparison, and risk / benefit analysis, with the aim of developing some appropriate level or form of response. Implicitly or explicitly risk evaluation involves balancing risk with the benefits associated with exposure to that risk. [2]
risk financing: The methods applied to fund risk treatment and the financial consequences of risk. Note: In some industries risk financing only relates to funding the financial consequences of risk. [2]
risk identification: The process of determining what adverse effects can happen, why and how. [2]
risk level: The level of risk calculated as a function of likelihood and consequence. [2]
risk management: The systematic process of using administrative decisions, organisation, operational skills and capacities to implement policies, strategies and coping capacities of the society and communities to lessen the impacts of natural hazards and related environmental and technological disasters. This comprises all forms of activities, including risk assessment, structural and non-structural measures to avoid (prevention) or to limit (mitigation and readiness) adverse effects of hazards. It involves the systematic application of management policies, procedures and practices to the tasks of establishing the context, identifying, analysing, evaluating, treating, monitoring and communicating risk. [2]
Risk management incorporates risk analysis, risk assessment and risk treatment.
risk perception: Intuitive understanding of risk based on an individual's own experience and judgement. [2]
risk reduction: A selective application of appropriate techniques and management principles to reduce the likelihood of the occurrence of a hazard, its intensity and/ or its consequences. [2]
risk retention: Intentionally or unintentionally retaining the responsibility for loss or financial burden of loss within the organisation. [2]
risk tolerance: A decision on the level of the tolerable residual risk after protection measures have been implemented. [2]
risk transfer: Shifting the responsibility or burden for loss to another party through legislation, contract, insurance or other means. Risk transfer can also refer to shifting a physical risk or part thereof elsewhere. [2]
risk treatment: That part of risk management which involves the implementation of policies, standards, procedures and physical changes to eliminate or minimise adverse risks. Incorporates the steps of assessing potential treatment options, developing a treatment plan detailing the selected options, implementing the plan, and monitoring / reviewing the plan. Also see counter measures. [2]
RMA: Resource Management Act 1991
scope definition: Involves establishing a brief and proposed methodology to analyse the risks associated with natural hazards. [7]
sea surge: A rise in sea level that results in the inundation of areas along coastlines. These phenomena are caused by the movement of ocean and sea currents, low-pressure cells, winds and major storms. [5]
secondary hazard : Those hazards that occur as a result of another hazard or disaster, i.e., fires or landslides following earthquakes, epidemics following famines, food shortages following drought or floods. [5]
seiche: (or underwater wave), pronounced say'sh. A standing wave in a body of water. The word originates in a Swiss-French dialect word that means "to sway back and forth", which had apparently long been used in the region to describe oscillations in alpine lakes. They are often hard to see on the surface of a water body due to the effects of gravity.
seismic isolation / base isolation: Systems used to limit the transfer of strong ground motion to a structure [5]
seismic zone: An area within which ground motion and seismic-design requirements for structures are similar [5]
seismic-activity rate: The mean number per unit time of earthquakes with specific characteristics (e g. magnitude 6) originating on a selected fault or in a selected area [5]
seismicity: The distribution of earthquakes in space and time. [5]
shear wall: A structural element which resists lateral forces. [5]
societal risk: the total risk attributed to the society responsible for bearing that risk (see also individual risk). [7]
storm: An atmospheric disturbance involving perturbations of the prevailing pressure and wind fields, on scales ranging from tornadoes (1 km across) to extratropical cyclones (2,000-3,000 km across). [5]
structural measures / non-structural measures: Structural measures refer to any physical construction to reduce or avoid possible impacts of hazards, which include engineering measures and construction of hazard-resistant and protective structures and infrastructure.
Non-structural measures refer to policies, awareness, knowledge development, public commitment, and methods and operating practices, including participatory mechanisms and the provision of information, which can reduce risk and related impacts. [4]
subsidence: Collapse of a considerable area of land surface, due to the removal of liquid or solid underlying or removal of soluble material by means of water. [5]
tephra: solid, fragmentary material ejected during a volcanic eruption such as ash, lapilli, blocks and bombs, except lava. [7]
tolerable risk: alevel of risk that a society is prepared to live with because there are net benefits in doing so, as long as that risk is monitored and controlled and action is taken to reduce it. See also risk tolerance. [7]
triggering factors: the final factors in a chain of causes leading to the occurrence of a hazard. [7]
tropical cyclone: Generic term for a non-frontal synoptic scale cyclone originating over tropical or sub-tropical waters with organized convection and definite cyclonic surface wind circulation, with winds generally over 33 knots Referred to as Typhoons in Asia and Hurricanes in the Atlantic. [5]
tropical depression: cell of low pressure originating in the tropics with wind speed up to 33 knots. [5]
tsunami: A series of large waves generated by sudden displacement of seawater (caused by earthquake, volcanic eruption or submarine landslide); capable of propagation over large distances and causing a destructive surge on reaching land. The Japanese term for this phenomenon, which is observed mainly in the Pacific, has been adopted for general usage. [5]
volcanic eruption: The discharge (aerially explosive) of fragmentary ejecta (see tephra), lava and gases from a volcanic vent. [5]
volcano: A vent from which a volcanic eruption occurs which may be associated with a mountain or other landform such as a caldera. [7]
voluntary risk: a risk that is taken despite full awareness of the consequences. [7]
vulnerability: The expected degree of loss to a given element or set of elements at risk, resulting from the occurrence of a natural hazard event of a given magnitude.
warning: An alarm signal or message coupled with a recommendation or order to take action (such as mobilize or evacuate). The warning is a more advanced stage of mobilization than the hazard watch and it pertains to conditions in which there is a high probability, or virtual certainty, that disaster will occur relatively soon (within minutes, hours, or at the most a few days). Warnings can be subdivided into the technological processes of conveying the message (i.e. communications systems) and the social process of informing the people and ensuring that they understand and act upon the warning message. Warnings are separate from predictions. Whereas the latter are the responsibility of scientists, warnings are the preserve of civil administrators. [1]
zoning: The division of a geographical area of land (e.g. a valley, town or region) into homogeneous sectors with respect to particular criteria (e.g. intensity of hazard, degree of vulnerability or risk, dependence on a particular operations centre). [1]
1 Alexander D E, 2002, Principles of Emergency Planning and Management, New York, Oxford University Press.
2 Australian Geomechanics Society, 2000, 'Landslide risk management: concepts and guidelines', Australian Geomechanics: 49-92.
3 Cruden D M and Fell R (Eds), 1997, Landslide risk assessment - Proceedings of the Workshop on Landslide Risk Assessment, Honolulu, Hawaii, USA, 19-21 February, Rotterdam, A.A. Balkema.
4 International Strategy of Disaster Reduction ISDR (http://www.unisdr.org/) terminology [updated, 2004]
5 International Decade of Natural Disaster Reduction IDNDR
6 Carter W N, 1991, Disaster Management: a Disaster Manager's Handbook, Asian Development Bank
7 Glade T, Anderson M, and Crozier M J, 2005, Landslide Hazard and Risk, Wiley, Chichester.
8 Resource Management Act 1991 (as amended by the Resource Management Amendment Act 2005).
9 Ministry of Civil Defence and Emergency Management, 2006, The Guide to the National CDEM Plan (Draft Version, 16 February 2006)
10 Ministry of Civil Defence & Emergency Management, 2004, Resilient New Zealand: A Aotearoa Manahau: National Civil Defence Emergency Management Strategy 2003-2006, ISBN 0-478-25461-X (www.civildefence.govt.nz).
12 www.seismo.unr.edu
Bibliography
Further explanations and definitions may be obtained from the following:
Aitchison J (Coordinator), 1989, International Thesaurus of Refugee Terminology, M. Nijhoff Publications, Dordrecht.
AS/NZS, 2004a, Australian/New Zealand Standard: Risk Management, HBAS/NZS 4360:2004
AS/NZS, 2004b, Australian/New Zealand Standard: Risk Management Handbook, companion to AS/NZS 4360:2004, HB 436:2004
Disaster Management Centre, 1991, Glossary, pp. 10, University of Wisconsin.
Gunn S W A, 1990, Multilingual Dictionary of Disaster Medicine and International Relief, Kluwer Acad. Publications, Dordrecht.
Hagman G, de Allwood A, Cutler P, Kassaye E, Kessely L, Kourmayev G A, Tolstopiatov B I, 1988, From Disaster Relief to Development, Henri Dunant Institute Studies on Development, No. 1, Geneva, 171-185.
Ockwell R, 1990, Disaster-related terminology, some observations and suggestions, A report to UNDRO.
Office of US Foreign Disaster Assistance, 1984, Glossary of International Disaster Assistance Terms: Natural Hazards, Appendix I, pp.134-150, OFDA, Washington DC.
Pan American Health Organisation, 1985, Disaster Planning: A Selected Bibliography, Disaster Preparedness Update Bibliography Series, No. 5, pp. 19, PAHO, Washington DC.
Steinbrugge K V, 1982, Earthquakes, volcanoes and tsunamis - an anatomy of hazards, Skandia America Group, Appendix 2, New York.
U.S. Geological Survey, 1984, Glossary of terms for probabilistic seismic risk and hazard analysis, Open-File report 84-7ķ0.
UNESCO Division of Earth Sciences, 1990, Glossary, pp. 12.
United Nations Disaster Relief Organisation, 1979, Natural Disasters and Vulnerability Analysis, UNDRO Geneva.
United Nations Disaster Relief Organisation, 1991, Mitigating Natural Disaster Phenomena: Effects and Options - A Manual, UNDRO Geneva.
World Meteorological Organisation, 1990, International Meteorological Vocabulary, WMO Geneva.
World Meteorological Organisation, 1991, International Glossary of Hydrology, WMO Geneva.
