Disaster Management

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Disaster is a sudden, calamitous event bringing great damage, loss, and destruction and devastation to life
and property. The damage caused by disasters is immeasurable and varies with the geographical location,
climate and the type of the earth surface/degree of vulnerability. This influences the mental, socio-
economic, political and cultural state of the affected area. Generally, disaster has the following effects in
the concerned areas,
 1. It completely disrupts the normal day to day life
 2. It negatively influences the emergency systems
 3. Normal needs and processes like food, shelter, health, etc. are affected and deteriorate depending on
          the intensity and severity of the disaster

It may also be termed as “a serious disruption of the functioning of society, causing widespread human,
material or environmental losses which exceed the ability of the affected society to cope using its own
Thus, a disaster may have the following main features:-
     o     Unpredictability
     o     Unfamiliarity
     o     Speed
     o     Urgency
     o     Uncertainty
     o     Threat

     Thus, in simple terms we can define disaster as a hazard causing heavy loss to life, property
         and livelihood.
     e.g. a cyclone killing 10,000 lives and a crop loss of one crore can be termed as disaster.

Generally, disasters are of two types – Natural and Manmade. Based on the devastation, these are
further classified into major/minor natural disaster and major/minor manmade disasters. Some of the
disasters are listed below,

                                                                   Minor natural disasters:
            Major natural disasters:
                                                                              Cold wave
                          Flood
                                                                            Thunderstorms
                        Cyclone
                                                                             Heat waves
                        Drought
                                                                              Mud slides
                       Earthquake
                                                                                Storm
Major manmade disaster:

        Setting of fires                          Minor manmade disaster:
        Epidemic                                      Road / train accidents, riots
        Deforestation                                 Food poisoning
        Pollution due to prawn cultivation            Industrial disaster/ crisis
                  Chemical pollution.                 Environmental pollution
                          Wars


An Earthquake is a sudden shake of the Earth's crust caused by the tectonic plates colliding.The
vibrations may vary in magnitude. The underground point of origin of the earthquake is called the "focus".
The point directly above the focus on the surface is called the"epicenter". Earthquakes by themselves
rarely kill people or wildlife. It is usually the secondary events that they trigger, such as building collapse,
fires,tsunamis (seismic sea waves) and volcanoes, that are actually the human disaster. Many of these
could possibly be avoided by better construction, safety systems, early warning and evacuation
planning.Earthquakes are caused by the discharge of accumulated along geologic fault.


A lahar is a volcanic mudflow or landslide. The 1953 Tangiwai disaster was caused by a lahar, as was the
1985 Armero tragedy in which the town of Armero was buried and an estimated 23,000 people were
What TSUNAMI means...

Tsunami is a Japanese word with the English translation, "harbor wave". Represented by two
characters, the top character, "tsu", means harbor, while the bottom character, "nami", means
"wave". In the past, the scientific community sometimes referred to tsunamis as "tidal waves".
The term "tidal wave" is a misnomer; although a tsunami's impact upon a coastline is dependent
upon the tidal level at the time a tsunami strikes, tsunamis are unrelated to the tides. Tides result
from the imbalance, extraterrestrial, gravitational influences of the moon, sun, and planets. The
term "seismic sea wave" is also misleading. "Seismic" implies an earthquake-related generation
mechanism, but a tsunami can also be caused by a non-seismic event, such as a landslide or
meteorite impact.


A tsunami can be generated by any disturbance that displaces a large water mass from its
equilibrium position. In the case of earthquake-generated tsunamis, the uplift (or subsidence) of
the sea floor disturbs the water column. Submarine landslides, which often accompany large
earthquakes, as well as collapses of volcanic edifices, can also disturb the overlying water
column as sediment and rock slump down slope and are redistributed across the sea floor.
Similarly, a violent submarine volcanic eruption can create an impulsive force that uplifts the
water column and generates a tsunami. Conversely, super marine landslides and cosmic-body
impacts disturb the water from above, as momentum from falling debris is transferred to the
water into which the debris falls. Generally speaking, tsunamis generated from these
mechanisms, unlike the Pacific-wide tsunamis caused by some earthquakes, dissipate quickly
and rarely affect coastlines distant from the source area.


Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the
overlying water. Tectonic earthquakes are a particular kind of earthquake that are associated with
the earth's crustal deformation; when these earthquakes occur beneath the sea, the water above
the deformed area is displaced from its equilibrium position. Waves are formed as the displaced
water mass, which acts under the influence of gravity, attempts to regain its equilibrium. When
large areas of the sea floor elevate or subside, a tsunami can be created. Tsunamis travel outward
in all directions from the epicenter of an earthquake.

Large vertical movements of the earth's crust can occur at plate boundaries. Plates interact along
these boundaries called faults. Around the margins of the Pacific Ocean, for example, denser
oceanic plates slip under continental plates in a process known as subduction. Subduction
earthquakes are particularly effective in generating tsunamis.

A drought (or drouth [archaic]) is an extended period of months or years when a region notes a
deficiency in its water supply. Generally, this occurs when a region receives consistently below
average precipitation. It can have a substantial impact on the ecosystemand agriculture of the affected
region. Although droughts can persist for several years, even a short, intense drought can cause
                           [1]                             [2]
significant damage               and harm the local economy.

This global phenomenon has a widespread impact on agriculture. The United Nationsestimates that an
area of fertile soil the size of Ukraine is lost every year because of drought,deforestation, and climate
instability.         Lengthy periods of drought have long been a key trigger for mass migration and played a key
role in a number of ongoing migrations and other humanitarian crises in the Horn of Africa and the SaheL

Periods of drought can have significant environmental, agricultural, health, economic and social
consequences. The effect varies according to vulnerability. For example, subsistence farmers are more
likely to migrate during drought because they do not have alternative food sources. Areas with
populations that depend on subsistence farming as a major food source are more vulnerable to drought-
triggered famine.

Types of drought
As a drought persists, the conditions surrounding it gradually worsen and its impact on the local
population gradually increases. People tend to define droughts in three main ways:

     1. Meteorological drought is brought about when there is a prolonged period with less than average
          precipitation. Meteorological drought usually precedes the other kinds of drought.
     2. Agricultural droughts are droughts that affect crop production or the ecology of the range. This
          condition can also arise independently from any change in precipitation levels
          whensoil conditions and erosion triggered by poorly planned agricultural endeavors cause a
          shortfall in water available to the crops. However, in a traditional drought, it is caused by an
          extended period of below average precipitation.
    3. Flood
    4. A flood is an overflow of an expanse of water that submerges land.                The EU Floods
        directive defines a flood as a temporary covering by water of land not normally covered by
        water.         In the sense of "flowing water", the word may also be applied to the inflow of thetide.
        Flooding may result from the volume of water within a body of water, such as a river orlake, which
        overflows or breaks levees, with the result that some of the water escapes its usual
        boundaries. While the size of a lake or other body of water will vary with seasonal changes in
        precipitation and snow melt, it is not a significant flood unless such escapes of water endanger
        land areas used by man like a village, city or other inhabited area.

    5. Floods can also occur in rivers, when flow exceeds the capacity of the river channel, particularly
        at bends or meanders. Floods often cause damage to homes and businesses if they are placed in
        natural flood plains of rivers. While flood damage can be virtually eliminated by moving away from
        rivers and other bodies of water, since time out of mind, people have lived and worked by the
        water to seek sustenance and capitalize on the gains of cheap and easy travel and commerce by
        being near water. That humans continue to inhabit areas threatened by flood damage is evidence
        that the perceived value of living near the water exceeds the cost of repeated periodic flooding.

[edit]Primary effects

       Physical damage - Can damage any type of structure, including bridges, cars,
    buildings, sewer systems, roadways, and canals.
       Casualties - People and livestock die due to drowning. It can also lead to epidemics and
    waterborne diseases.
[edit]Secondary effects

       Water supplies - Contamination of water. Clean drinking water becomes scarce.
       Diseases - Unhygienic conditions. Spread of water-borne diseases.
       Crops and food supplies - Shortage of food crops can be caused due to loss of entire
    harvest.         However, lowlands near rivers depend upon river silt deposited by floods in order to add
    nutrients to the local soil.
       Trees - Non-tolerant species can die from suffocation.
[edit]Tertiary/long-term effects

          Economic - Economic hardship, due to: temporary decline in tourism, rebuilding costs, food
    shortage leading to price increase ,etc.

          Earthquake
          An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of
           energy in the Earth's crust that creates seismic waves. Theseismicity or seismic activity of an
           area refers to the frequency, type and size of earthquakes experienced over a period of time.
           Earthquakes are measured with aseismometer; a device which also records is known as
           a seismograph. The moment magnitude (or the related and mostly obsolete Richter magnitude) of
           an earthquake is conventionally reported, with magnitude 3 or lower earthquakes being
           mostlyimperceptible and magnitude 7 causing serious damage over large areas. Intensity of
           shaking is measured on the modified Mercalli scale.

          At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacing
           the ground. When a large earthquake epicenter is located offshore, the seabed sometimes
           suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger
           landslides and occasionally volcanic activity.

          In its most generic sense, the word earthquake is used to describe any seismic event—whether a
           natural phenomenon or an event caused by humans—that generates seismic waves.
           Earthquakes are caused mostly by rupture of geologicalfaults, but also by volcanic activity,
           landslides, mine blasts, and nuclear experiments. An earthquake's point of initial rupture is called
           its focus or hypocenter. The term epicenter refers to the point at ground level directly above the


In order to determine the likelihood of future seismic activity, geologists and other scientists examine the
rock of an area to determine if the rock appears to be "strained". Studying the faults of an area to study
the buildup time it takes for the fault to build up stress sufficient for an earthquake also serves as an
effective prediction technique.            Measurements of the amount of accumulated strain energy on the fault
each year, time passed since the last major temblor, and the energy and power of the last earthquake are
made.          Together the facts allow scientists to determine how much pressure it takes for the fault to
generate an earthquake. Though this method is useful, it has only been implemented on California's San
Andreas Fault.

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hotmagma, ash and
gases to escape from below the surface.

Volcanoes are generally found where tectonic plates are diverging or converging. Amid-oceanic ridge, for
example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling
apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming
together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another.
Volcanoes can also form where there is stretching and thinning of theEarth's crust (called "non-hotspot
intraplate volcanism"), such as in the East African Rift, the Wells Gray-Clearwater volcanic field and
the Rio Grande Rift in North America.

Volcanoes can be caused by mantle plumes. These so-called hotspots, for example at Hawaii, can occur
far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on
rocky planets and moons.

Volcanic features

he most common perception of a volcano is of a conical mountain, spewing lava and
poisonousgases from a crater at its summit. This describes just one of many types of volcano, and the
features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on
a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit
crater, whereas others present landscape features such as massive plateaus. Vents that issue volcanic
material (lava, which is what magma is called once it has escaped to the surface, and ash) and gases
(mainly steam and magmatic gases) can be located anywhere on the landform.


Kilauea volcano

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