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1624851192.pptx

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The document discusses different types of hazards and how they are classified. It defines a hazard as a process, phenomenon or human activity that can cause harm. Hazards are divided into several categories - natural, biological, environmental, geological, hydrometeorological, and technological. The document also discusses how hazards can be characterized by their magnitude, speed of onset, duration and area affected. It describes how hazard events are measured and analyzed, including through the use of historical data and computer-generated hazard event sets. The severity of hazard impacts can potentially be lessened through risk reduction strategies and actions.

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4th Semester Paper-4016 ENVIRONMENTAL GEOGRAPHY AND DISASTER MANAGEMENT
CONCEPT OF HAZARD *HAZARD • A hazard is a process, phenomenon or human activity that may cause loss of life, injury or other health impacts, property damage, social and economic disruption or environmental degradation. Hazards may be natural, anthropogenic or socionatural in origin. (UNDRR Terminology ,2017) • Natural (or physical) events are only termed hazards when they have the potential to harm people or cause property damage, social and economic disruption. The location of natural hazards primarily depends on natural processes, including the movement of tectonic plates, the influence of weather systems, and the existence of waterways and slopes (e.g. that might generate landslides). But processes such as urbanization, environmental degradation and climate change can also influence the location, occurrence (frequency) and intensity of natural hazards. These processes are known as risk drivers.
The classification schemes for hazards vary across different research institutions and governments, but these can be divided into: • Biological hazards are of organic origin or conveyed by biological vectors, including pathogenic microorganisms, toxins and bioactive substances. Examples are bacteria, viruses or parasites, as well as venomous wildlife and insects, poisonous plants and mosquitoes carrying disease-causing agents. • Environmental hazards may include chemical, natural and biological hazards. They can be created by environmental degradation or physical or chemical pollution in the air, water and soil. However, many of the processes and phenomena that fall into this category may be termed drivers of hazard and risk rather than hazards in themselves, such as soil degradation, deforestation, loss of biodiversity, salinization and sea-level rise.
• Geological or geophysical hazards originate from internal earth processes. Examples are earthquakes, volcanic activity and emissions, and related geophysical processes such as mass movements, landslides, rockslides, surface collapses and debris or mud flows. Hydrometeorological factors are important contributors to some of these processes. Tsunamis are difficult to categorize: although they are triggered by undersea earthquakes and other geological events, they essentially become an oceanic process that is manifested as a coastal water-related hazard. • Hydrometeorological hazards are of atmospheric, hydrological or oceanographic origin. Examples are tropical cyclones (also known as typhoons and hurricanes); floods, including flash floods; drought; heatwaves and cold spells; and coastal storm surges. Hydrometeorological conditions may also be a factor in other hazards such as landslides, wildland fires, locust plagues, epidemics and in the transport and dispersal of toxic substances and volcanic eruption material
• Technological hazards originate from technological or industrial conditions, dangerous procedures, infrastructure failures or specific human activities. Examples include industrial pollution, nuclear radiation, toxic wastes, dam failures, transport accidents, factory explosions, fires and chemical spills. Technological hazards also may arise directly as a result of the impacts of a natural hazard event. • Each hazard often triggers a sub-set of hazards, for instance tropical cyclones (known as hurricanes in the Atlantic Ocean, cyclones in the Indian Ocean and typhoons in the Northern Pacific Ocean) can bring intense winds, storm surge and heavy rainfall, as well as trigger secondary hazards, for instance landslides. A series of triggering relationships can cause a domino or cascading effect, for instance in the case of the tsunami-earthquake-nuclear crisis in Japan, 2011.
Characteristics of hazards • Natural hazard events can be characterized by their magnitude or intensity, speed of onset, duration, and the area they cover. • Hazards occur at different intensities (or magnitudes) over different time scales (sometimes known as temporal scales). Scientists talk about the occurrence of hazards of different intensities in terms of probabilties or return periods (also known as recurrence intervals), within the context of uncertainty. In general, the longer the return period (the less frequent the hazard) the greater the intensity of the hazard. Because of these long return periods, some communities may have no memory of the potential threat of a high intensity hazard. • Hazards also occur at different geographical (spatial) scales. For instance, the occurrence and impact of tornadoes tends to be quite localised, whereas droughts can occur over several tens of thousands of kilometres
• Many countries are exposed to multiple hazards. It is therefore essential to consider the risk related to the full range of hazards that might affect people or assets. How hazards can be measured? • Essential steps in hazard assessment are identifying the relevant hazard(s) and the collection of hazard-related data. Once the hazards are defined, the next step often involves obtaining a variety of hazard-related data. The most essential data define the date, geographical location and extent, and maximum intensity of historical events. A collection of the spatial, intensity, and temporal characteristics for events in an event set is termed a hazard catalogue. Hazard catalogues can be used with risk models in a deterministic or probabilistic manner.
• This process may include difficult decisions, such as whether to consider secondary (or chains of) hazards that might be triggered by a primary event (e.g. a fire after an earthquake) and/or the interactions between hazards. • Historical events are often used in deterministic analyses that assess the impact of past events with current exposure, but can also be used to estimate the probability of a hazard occurring at a location with a specific intensity. However, we have already identified that high intensity hazards tend to occur infrequently and have long return periods. This means that many of the intensities of hazards (and ultimately disasters) that could occur have not yet happened, which is particularly the case for geological hazards because they often occur over long time periods. Historical records of these types of events do not show the true picture of hazard return periods.
• Computer generated hazard events with statistical characteristics consistent with the historical record are therefore used to ""complete"" hazard catalogues. Such event sets can typically include thousands or tens of thousands of potential events and are intended to define the full range of potential events for a hazard. Event sets are used with information on exposure and vulnerability to quantify probabilities of loss and risk from a hazard. A probabilistic risk model contains a compilation of all possible “impact scenarios” for a specific hazard and geographical area • The adverse impacts of hazards, in particular natural hazards, often cannot be prevented fully, but their scale or severity can be substantially lessened by various strategies and actions.
TERMINOLOGIES • UNDRR-United Nations Office for Disaster Risk Reduction • It was formerly UNISDR(United Nations International Strategy for Disaster Reduction) REFERENCES/SOURCE *Environmental geography,Savindra Singh *Environmental geography,R.C Chandna *Websites-Office of Disaster preparedness And Management(Govt. Of the Republic of Trinidad)

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1624851192.pptx

  • 2. CONCEPT OF HAZARD *HAZARD • A hazard is a process, phenomenon or human activity that may cause loss of life, injury or other health impacts, property damage, social and economic disruption or environmental degradation. Hazards may be natural, anthropogenic or socionatural in origin. (UNDRR Terminology ,2017) • Natural (or physical) events are only termed hazards when they have the potential to harm people or cause property damage, social and economic disruption. The location of natural hazards primarily depends on natural processes, including the movement of tectonic plates, the influence of weather systems, and the existence of waterways and slopes (e.g. that might generate landslides). But processes such as urbanization, environmental degradation and climate change can also influence the location, occurrence (frequency) and intensity of natural hazards. These processes are known as risk drivers.
  • 3. The classification schemes for hazards vary across different research institutions and governments, but these can be divided into: • Biological hazards are of organic origin or conveyed by biological vectors, including pathogenic microorganisms, toxins and bioactive substances. Examples are bacteria, viruses or parasites, as well as venomous wildlife and insects, poisonous plants and mosquitoes carrying disease-causing agents. • Environmental hazards may include chemical, natural and biological hazards. They can be created by environmental degradation or physical or chemical pollution in the air, water and soil. However, many of the processes and phenomena that fall into this category may be termed drivers of hazard and risk rather than hazards in themselves, such as soil degradation, deforestation, loss of biodiversity, salinization and sea-level rise.
  • 4. • Geological or geophysical hazards originate from internal earth processes. Examples are earthquakes, volcanic activity and emissions, and related geophysical processes such as mass movements, landslides, rockslides, surface collapses and debris or mud flows. Hydrometeorological factors are important contributors to some of these processes. Tsunamis are difficult to categorize: although they are triggered by undersea earthquakes and other geological events, they essentially become an oceanic process that is manifested as a coastal water-related hazard. • Hydrometeorological hazards are of atmospheric, hydrological or oceanographic origin. Examples are tropical cyclones (also known as typhoons and hurricanes); floods, including flash floods; drought; heatwaves and cold spells; and coastal storm surges. Hydrometeorological conditions may also be a factor in other hazards such as landslides, wildland fires, locust plagues, epidemics and in the transport and dispersal of toxic substances and volcanic eruption material
  • 5. • Technological hazards originate from technological or industrial conditions, dangerous procedures, infrastructure failures or specific human activities. Examples include industrial pollution, nuclear radiation, toxic wastes, dam failures, transport accidents, factory explosions, fires and chemical spills. Technological hazards also may arise directly as a result of the impacts of a natural hazard event. • Each hazard often triggers a sub-set of hazards, for instance tropical cyclones (known as hurricanes in the Atlantic Ocean, cyclones in the Indian Ocean and typhoons in the Northern Pacific Ocean) can bring intense winds, storm surge and heavy rainfall, as well as trigger secondary hazards, for instance landslides. A series of triggering relationships can cause a domino or cascading effect, for instance in the case of the tsunami-earthquake-nuclear crisis in Japan, 2011.
  • 6. Characteristics of hazards • Natural hazard events can be characterized by their magnitude or intensity, speed of onset, duration, and the area they cover. • Hazards occur at different intensities (or magnitudes) over different time scales (sometimes known as temporal scales). Scientists talk about the occurrence of hazards of different intensities in terms of probabilties or return periods (also known as recurrence intervals), within the context of uncertainty. In general, the longer the return period (the less frequent the hazard) the greater the intensity of the hazard. Because of these long return periods, some communities may have no memory of the potential threat of a high intensity hazard. • Hazards also occur at different geographical (spatial) scales. For instance, the occurrence and impact of tornadoes tends to be quite localised, whereas droughts can occur over several tens of thousands of kilometres
  • 7. • Many countries are exposed to multiple hazards. It is therefore essential to consider the risk related to the full range of hazards that might affect people or assets. How hazards can be measured? • Essential steps in hazard assessment are identifying the relevant hazard(s) and the collection of hazard-related data. Once the hazards are defined, the next step often involves obtaining a variety of hazard-related data. The most essential data define the date, geographical location and extent, and maximum intensity of historical events. A collection of the spatial, intensity, and temporal characteristics for events in an event set is termed a hazard catalogue. Hazard catalogues can be used with risk models in a deterministic or probabilistic manner.
  • 8. • This process may include difficult decisions, such as whether to consider secondary (or chains of) hazards that might be triggered by a primary event (e.g. a fire after an earthquake) and/or the interactions between hazards. • Historical events are often used in deterministic analyses that assess the impact of past events with current exposure, but can also be used to estimate the probability of a hazard occurring at a location with a specific intensity. However, we have already identified that high intensity hazards tend to occur infrequently and have long return periods. This means that many of the intensities of hazards (and ultimately disasters) that could occur have not yet happened, which is particularly the case for geological hazards because they often occur over long time periods. Historical records of these types of events do not show the true picture of hazard return periods.
  • 9. • Computer generated hazard events with statistical characteristics consistent with the historical record are therefore used to ""complete"" hazard catalogues. Such event sets can typically include thousands or tens of thousands of potential events and are intended to define the full range of potential events for a hazard. Event sets are used with information on exposure and vulnerability to quantify probabilities of loss and risk from a hazard. A probabilistic risk model contains a compilation of all possible “impact scenarios” for a specific hazard and geographical area • The adverse impacts of hazards, in particular natural hazards, often cannot be prevented fully, but their scale or severity can be substantially lessened by various strategies and actions.
  • 10. TERMINOLOGIES • UNDRR-United Nations Office for Disaster Risk Reduction • It was formerly UNISDR(United Nations International Strategy for Disaster Reduction) REFERENCES/SOURCE *Environmental geography,Savindra Singh *Environmental geography,R.C Chandna *Websites-Office of Disaster preparedness And Management(Govt. Of the Republic of Trinidad)