Key Terms

Planning Process

Capability Assessment: Provides a description and analysis of a community’s current capacity to address threats associated with hazards. The assessment includes two components: an inventory of an agency’s mission, programs, and policies, and an analysis of its capacity to carry them out. A capability assessment is an integral part of the planning process in which a community’s actions to reduce losses are identified, reviewed, and analyzed, and the framework for implementation is identified.

Disaster Mitigation Act of 2000 (DMA 2000): Federal legislation enacted to encourage and promote proactive, pre-disaster planning as a condition of receiving financial assistance under the Robert T. Stafford Act. The DMA emphasizes planning for disasters before they occur. Under the DMA, a pre-disaster hazard mitigation program and new requirements for the national post-disaster hazard mitigation grant program (HMGP) were established.

Federal Emergency Management Agency (FEMA): An independent federal agency (now part of the Department of Homeland Security) created in 1978 to provide a single point of accountability for all federal activities related to disaster mitigation and emergency preparedness, response, and recovery.

Geographic Information System (GIS): A computer software application that relates data regarding physical and other features on the earth to a database for mapping analysis.

Goal: A general guideline that explains what is to be achieved. Goals are usually broad-based, long-term, policy-type statements, and represent global visions. Goals help define the benefits that a plan is trying to achieve.

Hazard: A source of potential danger or adverse condition that could harm people and/or cause property damage

Hazard Mitigation: Reduction or alleviation of the loss of life, personal injury, and property damage that could result from a disaster through long- and short-term strategies. Hazard mitigation involves strategies such as planning, policy changes, programs, projects, and other activities that could mitigate the impacts of hazards

Hazard Mitigation Grant Program (HMGP): Authorized under Section 202 of the Robert T. Stafford Disaster Relief and Emergency Assistance Act, the HMGP is administered by FEMA and provides grants to states, tribes, and local governments to implement hazard mitigation actions after a major disaster declaration.  The purpose of the program is to reduce the loss of life and property due to disasters and to enable mitigation activities to be implemented as a community recovers from a disaster

Hazard Mitigation Plan (HMP): A collaborative document that identifies hazards that could affect a community, assesses vulnerability to identified hazards, and presents existing and potential actions that the community is undertaking or intends to undertake in order to minimize or eliminate the effects of hazards.

Mitigation Actions: Specific projects, plans, or policies that achieve goals and objectives that minimize the effects from a disaster and reduce the loss of life and property.

Mitigation Strategy: A systematic process for analyzing, prioritizing, and implementing the identified mitigation actions in the Hazard Mitigation Plan.

Natural Hazard: Hazard which results from conditions in the natural environment. Humans may contribute to or exacerbate the hazard, but are not the direct source of the hazard.

Non-Natural Hazard: Hazard which results from human-induced processes.

Preparedness: Actions that strengthen the capability of government, citizens, and communities to respond to disasters.

Presidential Disaster Declaration: Typically made for events that cause more damage than state and local governments and resources can handle without federal government assistance. Generally, no specific dollar loss threshold has been established for such declarations. A Presidential Disaster Declaration puts into motion long-term federal recovery programs, some of which are matched by state programs, designed to help disaster victims, businesses, and public entities.

Recovery: Recovery refers to actions taken by an individual or community after a catastrophic event to restore order and community lifelines.

Resiliency: The capacity of the social, built, or natural environment to bounce back and return to normalcy following a disaster.

Risk: The estimated impact that a hazard would have on people, services, facilities, and structures in a community. Risk measures the likelihood of a hazard occurring and resulting in an adverse condition that causes injury or damage. Risk is often expressed in relative terms such as a high, moderate, or low hazard. Risk also can be expressed in terms of potential monetary losses associated with the intensity of likelihood of sustaining damage above a particular threshold due to occurrence of a specific type of the hazard.

Risk Assessment: The process of measuring potential loss of life, personal injury, economic injury, and property damage resulting from hazards. This process assesses the vulnerability of people, buildings, and infrastructure to hazards and focuses on severity, probability, impact to the social, built, natural, and future environment.

Hazard Specific

Coastal Erosion

Coastal Erosion: Loss or displacement of land along the coastline from the interaction of oceans, waves, and beaches, often coupled with the impact human activity. 

Coastal Erosion Hazard Area (CEHA): Coastal locations that are particularly vulnerable to erosion requiring written approval of regulated activities or land disturbance to properties within these areas.

Landslides: The downward and outward movement of slope-forming materials reacting to the force of gravity. Slide materials may be composed of natural rock, soil, artificial fill, or combinations of these materials. The term landslide includes rock falls, rockslides, block glide, debris slide, earth flow, mudflow, slump, and other such terms.

Natural Protective Feature Area (NPFA): Portion of Coastal Erosion Hazard Area (CEHA) which contains natural protective features that protect natural habitats, infrastructure, and built structures from wind and water erosion and storm-induced high water.

Structural Hazard Areas: Section of the Coastal Erosion hazard Area located landward of natural protective features and having shorelines receding a long-term average recession rate of one foot or more per year.

Coastal Storms

Bearing: A storm’s direction and angle of approach.

Coastal Storms: Including tropical cyclones formed in the atmosphere over warm ocean areas, and nor’easters which form at higher latitudes during the colder months of the year. Circulation is counterclockwise around a center of low pressure. Depending on the exact storm type, coastal storms can affect the area with heavy rain, winds, storm surge, tornadoes, or wintry precipitation

Hurricane: A tropical cyclone with winds that have reached a constant speed of 74 miles per hour or greater.

New  York Bight: A bight is a curve in the shoreline of an open coast that funnels and increases the speed of storm surge. The New York Bight is located at the point where New York and New Jersey meet, creating nearly a right angle in the coastline

Nor’easter: A strong low-pressure system that affects the Mid-Atlantic and New England states. Nor’easters can form over land or coastal waters, generally between October and April. These events are notorious for producing heavy snow, rain, and tremendous waves that crash onto Atlantic beaches, often causing beach erosion and structural damage.

Saffir-Simpson Hurricane Wind Scale: Primary scale used to measure the hurricane’s sustained wind speed based on a scale of 1 to 5.

Sea, Lake, and Overland Surges from Hurricanes (SLOSH): Computer model which calculates surge based on storms moving in different directions and with varying strengths.

Severe Thunderstorm: Thunderstorms consisting of winds of 58 mph or higher, and/or large hail measuring at least 1 inch in diameter, and/or a tornado. About 10% of thunderstorms are classified as severe.

Storm Surge: An abnormal rise in water level above the normal astronomical tide level as it is pushed towards the shore by the force of the winds and low pressure of a storm. It is measured as the different between the normal astronomical tide levels and observed storm water levels, or storm tide.

Storm Surge Inundation: The storm surge height above ground level, calculated by subtracting the total land elevation from the total storm surge height.

Storm Tide: When storm surge combines with the astronomical high tide, raising mean water level and causing severe inundation of coastal areas.

Tropical Cyclone: Organized areas of precipitation and thunderstorms that form over warm, tropical ocean waters. Rotation is counterclockwise around a low pressure center.

Tropical Depression: A tropical cyclone consisting of an organized system of clouds and thunderstorms, with a defined surface circulation, and maximum sustained winds of 38 miles per hour or less.

Tropical Storm: A tropical cyclone consisting of an organized system of strong thunderstorms, with a defined surface circulation, and maximum sustained winds of 39 to 73 miles per hour.


Earthquake: A sudden, rapid shaking of the earth caused by the breaking and shifting of rock beneath the surface, usually within the upper 10-20 miles of the earth’s surface.

Epicenter: Point on the surface directly above the source of an earthquake.

Focus (earthquakes): An earthquake’s location of origin beneath the surface.

Ground Acceleration: Shaking of the ground resulting from seismic waves caused by an earthquake.

Intensity (earthquakes): Used to describe the overall felt severity of shaking during an earthquake at a particular location, measured in terms of the Modified Mercalli scale.

Liquefaction: Occurs when unconsolidated, water-saturated soils exhibit fluid-like or significantly softened properties due to the intense shaking and vibrations during an earthquake.

Magnitude (earthquakes): A measurement of the energy released at the source of the earthquake expressed by ratings on the Moment Magnitude Scale.

Modified Mercalli Intensity (MMI): A scale used for measuring the intensity of an earthquake. The scale quantifies the effects of an earthquake on the Earth’s surface, humans, objects of nature, and man-made structures on a scale of I through XII, with I denoting a weak earthquake and XII one that causes almost complete destruction.

Peak Ground Acceleration (PGA): The maximum acceleration experience by the ground during the course of an earthquake motion, described by its changing velocity as a function of time. It is expressed as a percent of the established rate of acceleration due to gravity (9.8 m/sec2).

Moment Magnitude Scale: A logarithmic scale used to express the total amount of energy released by an earthquake. It is a logarithmic scale – a single step represents an increase of about 32 times the amount of energy released.

Spectral Acceleration (SA): Measures what is experienced by a building during an earthquake by referencing a particle mass on a mass-level vertical rod having the same natural period of vibration as the building.

Extreme Heat

Excessive Heat Warning: Issued within 24 hours of onset of the following condition: Heat index of at least 105°F.

Extreme Heat: Temperatures that hover 10°F or more above the average high temperature for the region and last for several weeks. Humid or muggy conditions, which add to the discomfort of high temperatures, occur when a “dome” of high atmospheric pressure traps hazy, damp air near the ground.

Heat Advisory: Issued within 24 hours prior to onset of any of the following conditions: 1) Heat index of 100°F-104°F for any period 2) Heat Index of 95°F-99°F or greater for two consecutive days.

Heat Exhaustion: A health condition brought on by prolonged exposure to extreme heat, with symptoms including confusion, dizziness, fatigue, nausea, headaches, and muscle cramps.

Heat Index: The temperature the body feels when heat and humidity are combined. Higher humidity reduces the body’s ability to cool itself and makes the temperature feel hotter.

Heat Stroke: Occurs when the body is no longer able to regulate its internal temperature, resulting in a body temperature of greater than 105°F. Common symptoms include seizures, disorientation, loss of consciousness, and complications involving the central nervous system.

Urban Heat Island Effect: Develop when built surfaces replace a large portion of natural land. Incoming solar radiation is trapped during the day and is then re-radiated at night. This slows the cooling process, keeping nighttime air temperatures high, relative to temperatures in less urbanized areas.


1% Annual Chance Flood: The area where there is 1% chance of flooding in any given year. Formerly referred to as a “100-year-flood.”

0.2% Annual Chance Flood: The area where there is a 0.2 % or greater chance of flooding in any given year. Also called the “500-year-flood.”

Base Flood Elevation: FEMA’s flood maps identify the expected height of flooding from the 1% annual chance flood for each zone, known as the Base Flood Elevation. The Base Flood Elevations are denoted in the datum NAVD 88, which represents the number of feet above mean sea level in that datum.

Coastal Flooding

Primarily caused by the storm surge that generally accompanies a strong coastal storm, such as a tropical storm, hurricane, or nor’easter.

Flood: A general and temporary condition of partial or complete inundation or normally dry land. Flooding can be categorized as coastal, riverine, tidal, or inland.

Flood Insurance Rate Map (FIRM): The official map of a community for which FEMA has designated flood zones – geographic areas classified according to levels of flood risk, with each zone reflecting a different severity and/or type of flooding – and the insurance risk premium zones applicable to the community.

Flood Zone Categories:

VE: Coastal areas subject to inundation by a 1 percent annual chance flood. Additional hazards associated with storm-induced waves more than 3 feet high

Coastal A:  A sub-area of the A/AE flood zone that has additional hazards associated with storm-induced waves that are between 1.5 to 3 feet high

AE: Areas subject to inundation by a 1% annual chance flood

X: Areas of moderate flood hazard subject to inundation by a 0.2% annual chance flood, also called the “500 year flood zone”

Hazards US Multi-Hazards (HAZUS-MH): A nationally applicable standardized methodology and software program, developed by FEMA, which is under contract with the National Institute of Building Sciences. The program estimates potential losses from earthquakes, hurricane winds, and floods. In HAZUS-MH, current scientific and engineering knowledge is coupled with Geographic Information Systems (GIS) technology to produce estimates of hazard-related damage before, or after, a disaster occurs.

Mean Lower Low Water (MLLW): The average height of the lowest tide recorded at a tide station each day during a recording period.

Maximum Envelope of Water (MEOW): SLOSH output showing the maximum surge inundation from a set hypothetical storms with fixed intensity and bearing but varied size, forward speed, and landfall locations.

Maximum of MEOWs (MOMs): SLOSH output which represents the worst-case scenario storm surge.

National Flood Insurance Program (NFIP): Program through which FEMA sets insurance premiums and minimum building standards for properties in the 1 Percent annual chance floodplain. The three components of the NFIP are flood insurance, floodplain management, and flood hazard mapping. Nearly 20,000 communities across the United States and its territories participate in the NFIP by adopting and enforcing floodplain management ordinances to reduce future flood damage. In exchange, the NFIP makes federally backed flood insurance available to homeowners, renters, and business owners in these communities. Community participation in the NFIP is voluntary.

Probabilistic (for HAZUS-MH): Events modeled by looking at the damage caused by an event that is likely to occur over a given period of time, known as a return period.

Repetitive Loss Property: Structures for which a policyholder receives two or more claim payments of $1,000 or more after flood events within a 10-year period.

Riverine Flooding: Occurs when freshwater rivers and streams exceed local flow capacity and water spills over their banks.

Severe Repetitive Loss Structure: Any insured structure that has incurred flood damage for which:

  • At least two separate claim payments have been made under a Standard Flood Insurance Policy, with the cumulative amount of such payments exceeds the fair market value of the insured buildings on the day before each loss: or
  • At least four or more claim payments over $5,000 and with the cumulative amount of claim payments exceeding $20,000.

Stillwater Flooding: A rise in water levels without significant waves.

Tidal Flooding: Also known as “nuisance flooding,” “blue-sky flooding, or “sunny day flooding” is caused by normal variations in the lunar cycle and can occur even in the absence of a storm.

High Winds

Beaufort Wind Scale: A simplified scale to aid in the estimation of wind speed and corresponding typical effects.

Enhanced Fujita Scale: National Weather Service’s revised Fujita-scale, which is a complex, systematic approach to measuring the strength of a tornado.

Fujita Scale (F-Scale): Standard measurement for rating the strength of a tornado.

Micro/Macroburst: Associated with a thunderstorm, Micro/Macrobursts are powerful downdrafts that can cause severe, localized damage.

Straight-line winds: Typically blow in one direction but can vary during the course of an event. Speeds exceed 50-60 mph and are associated with intense low atmospheric pressure.  Duration usually lasts up to one day.

Tornadoes: A local atmospheric storm, generally of short duration, formed by winds rotating at very high speeds, usually in a counterclockwise direction. The vortex is visible to the observer as a whirl-pool-like column of winds rotating about a hollow cavity or funnel. Wind speeds range from 65 to 300 miles per hour.

Winter Weather

Extreme Cold: Temperatures that drop well below normal in an area. Whenever temperatures drop well below normal and wind speed increases, heat can leave your body more rapidly (known as the wind-chill effect).

Freezing Rain: Precipitation that falls as rain, but freezes on contact with the surface, forming a glaze of ice.

Frostbite: Freeing of the body’s outer tissue as a result of prolonged exposure to extreme cold. Most commonly occurs in the outer extremities like the nose, ears, cheeks, chin, fingers, and toes. Symptoms include numbness, tingling or stinging, aching, and discoloration of the skin.

Hail: Precipitation in the form of irregular pellets, or balls of ice more than five millimeters in diameter, falling from thunderstorm.

Hypothermia: A significant lowering of internal body temperature which occurs due to prolonged exposure to extreme cold. Early symptoms of hypothermia include shivering, fatigue, loss of coordination, and disorientation. If continued untreated, this condition becomes more serious, with recognizable symptoms including blue skin, dilated pupils, slow pulse and breathing, or loss of consciousness.

Ice storms: Occur when freezing rain results in dangerous accumulations of ice, usually ¼ inch or greater.

Sleet: Sleet is defined as pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes

Snow: Precipitation in the form of ice crystals that form directly from water vapor freezing in the air.

Snow Showers: Snow falling at varying intensities for brief periods with accumulations of one inch or less.

Snowsquall: Intense, brief periods of moderate-to-heavy snowfall, accompanied by strong, gusty surface winds and possibly lightning, with risk of significant snow accumulation.

Thundersnow: A snowstorm accompanied by thunder and lightning, which can occur over intense low pressure systems or other similar conditions of relatively strong instability and abundant moisture.

Wind-Chill Effect: Measures apparent temperature felt on exposed skin due to the combination of air temperature and wind speed. This occurs because wind causes heat to leave the body more rapidly.


Accidental Releases: Hazardous materials releases that result from human error, tainted food products, technological failure, or natural disaster. These include spills, leaks, and airborne releases.

Chemical Hazard: A substance with the potential to cause harm, primarily to humans, through toxicity, reactivity, corrosivity, or flammability.

Dose (radiation): Amount of energy absorbed by the body.

Dose Equivalent (radiation): Considers dose absorbed and the type of radiation to which one is exposed.

Hazardous Materials (HAZMAT) Incidents: A situation in which hazardous materials are released into the environment, causing a threat to human health and safety. Such incidents are often classified as chemical, biological, radiological, and nuclear (CBRN).

Intentional Releases: Hazardous materials release that are criminal acts. These include purposeful dumping by businesses to avoid regulatory requirements, or terrorist acts that target a specific location, possibly involving a dispersal or an explosive.

Latency: Time interval between exposure and the development of clinical symptoms.

Persistency: Time it takes for the chemical to disperse.

Radiological Hazard: When harmful doses of radiation come into contact with humans. Can occur when external radiation comes into contact with a person’s skin, hair, or clothing, or through inhalation or ingestion.

Toxicity: Degree to which the chemical impairs human health.

Transmissibility: Potential passage of the chemical between exposed persons and others, particularly rescue workers, such as hospital staff.

Cyber Threats

Cyber Attack: A cyber incident that is intentional or malicious in nature.

Cyber Crime: A cyber attack that is primarily motivated by financial gain.

Cyber Threat: An adverse event in an information system or network in which the digital infrastructure of a person or organization is compromised.

Hacktivism: The act of hacking, or breaking into a computer system for a politically or socially motivated purpose.

Emerging Diseases

Endemic (disease): Refers to the usual presence of a disease within a specific population or area.

Epidemic: The sometimes-sudden increase in the number of cases of a disease that exceeds what is normally expected.

Respiratory Viruses

Health Risk Assessment: Process of evaluating the existence and/or magnitude of health problems resulting from exposure to a hazardous substance. The four steps in this process are health problem identification, toxicology (dose response), exposure assessment, and health risk characterization.

Pandemic: An epidemic that has spread across a region or over several countries.

Mitigation Strategy

Benefit-Cost Analysis (BCA): A systematic, quantitative method of comparing projected benefits to projected cost of a project or policy. It is used as a measure of cost effectiveness.

Coastal/Natural Resource Protection : Actions that, in addition to minimizing hazard losses, also preserve or restore the functions of natural or coastal systems.

Education and Awareness: Actions that protect people and property, or increase the capacity of emergency response during and immediately following a disaster event.

Emergency Services: Actions that protect people and property, or increase the capacity of emergency response.

Existing Mitigation Action: A project, plan, policy, or program the City has already taken or has begun to implement that addresses natural hazard mitigation.

Infrastructure Projects: Actions that involve the engineering of infrastructure systems to be more resistant to the impacts of hazards.

Potential Mitigation Action: A project, plan, policy, or program that the City would like to take to address hazard mitigation, but currently does not have the funds and/or resources to implement.

Prevention and Policy: Government, administrative, or regulatory actions and processes that influence the way land buildings are developed and built. These actions also include public activities that reduce hazard losses. Examples of this category include building and construction code revisions, zoning regulation changes, and hazard computer modeling.

Property Protection: Actions that involve the modification of existing buildings or structures to protect them from a hazard, or removal from the hazard area.

STAPLEE: A set of criteria used to examine the Social, Technical, Administrative, Political, Legal, Economic, and Environmental (STAPLEE) opportunities and constraints of implementing a particular mitigation measure during a consistent framework.

All Hazards

Barrier Islands: A long offshore deposit of sand parallel to the coastline which act as a buffer against storms by absorbing the most severe impacts of waves and storm surge.

Building Value: Assessed value of the physical building.

Critical Facilities: A critical facility is vital to the City’s ability to provide essential services and protect life and property. Loss of a critical facility would result in a severe economic or catastrophic impact.

Debris: The scattered remains of assets broken or destroyed during the occurrence of a hazard. Debris caused by wind or water hazards can cause additional damage to other assets.

Deterministic (for HAZUS-MH): Estimates of hazard-related damage to a city or a region from a hypothetical “hazard event” of a fixed severity and location.

Geomorphology: The study of geographic features and landforms and the processes that shape them over time.

Go-Outside-the-Home Disability: Conditions lasting six or more months that make going outside the home alone to shop or visit a doctor’s office difficult.

Linguistically Isolated: Limited English-proficiency, people who speak English less than “very well”.

New York City Construction Code: The City’s comprehensive building code managed by the New York City Department of Buildings.

Outwash Plains: Deposits of sand, silt, and clay deposited by glaciers which compromise the low-lying areas of eastern Staten Island, and southern Brooklyn and Queens.

Physical Disability: Long-lasting conditions that substantially limit one or more basic physical activity, such as walking, climbing stairs, reaching, lifting, or carrying.

Public Health Jurisdictional Risk Assessment (JRA): An assessment of the past, current, and future risks to the health, safety, and property of the people within that jurisdiction.

Return Period: Average period of time in years between occurrences of a particular hazard (equal to the inverse of the annual frequency of occurrence).

Self-Care Disability: Conditions lasting six or more months that make dressing, bathing, or getting around inside the home difficult.

Sensory Disability: Blindness, deafness, or a severe vision or hearing impairment.

Susceptibility: Factors which make certain populations more at-risk to a hazard, including predisposition, stress, environmental factors, and behavioral factors.

Terminal Moraine: Rock debris deposited by glaciers. Terminal Moraine areas in the city are located in the  hilly portions through Staten Island and central Brooklyn/Queens.

Utility Disruptions: Disruptions to essential utilities, including energy (electric, gas, and steam) and communications.

Vulnerability: Refers to a reduced capacity of the social, built, or natural environment to cope with, resist, or recover from the impact of a hazard.


Boroughs: The five geographic and political divisions of New York City, each classified as an individual county. The five Boroughs of New York City are the Bronx, Brooklyn (Kings), Manhattan (New York), Queens, and Staten Island (Richmond).

Community District: 59 distinct geographical boundaries within New York City that haven an important advisory role in dealing with land use and zoning matters, the City budget, the municipal service delivery, and many other matters relating to their communities’ welfare.