Disaster is a sudden, 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.

Natural disasters:

            A natural disaster is the effect of a natural hazard that affects the environment, and leads to financial, environmental and/or human losses. The resulting loss depends on the capacity of the population to support or resist the disaster, and their resilience.

Examples:

1.    Flood

2.    Cyclone

3.    Drought

4.    Earthquake

5.    Thunderstorms

6.    Heat waves

7.    Mud slides

Man-made disasters are events which, either intentionally or by accident cause severe threats to public health and well-being. Because their occurrence is unpredictable, man-made disasters pose an especially challenging threat that must be dealt with through vigilance, and proper preparedness and response.

Examples:

1.    Setting of fires

2.    Epidemic

3.    Deforestation

4.    Pollution due to prawn cultivation

5.    Chemical pollution.

6.    Wars

7.    Road / train accidents, riots

8.    Food poisoning

9.    Industrial disaster/ crisis

Disaster recovery is the process, policies and procedures related to preparing for recovery or continuation of technology infrastructure critical to an organization after a natural or human-induced disaster.

            Disaster recovery planning is a subset of a larger process known as business continuity planning and should include planning for resumption of applications, data, hardware, communications (such as networking) and other IT infrastructure.

Management is of course a key part of the the disaster recovery planning process. To be successful it requires a firm understanding of the concepts, structures required, the cultural aspects, the different requisite activities,

            the different plans and elements within, the different phases and activities within the planning process, the critical success factors, and of course much more.

Service	Phone Numbers
Police	100
Traffic Police	103
Police (outside city limits)	108
Fire Control	101
Ambulance of Fire Services Dept.	102
Child Line	1098
Women Help Line	1091
Lions Blood Bank	1910

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1.             Battery operated torch
2.             Extra batteries
3.             Battery operated radio
4.             First aid kit and manual
5.             Emergency food (dry items) and water (packed and sealed)
6.             Candles and matches in a waterproof container
7.             Knife
8.             Chlorine tablets or powdered water purifiers
9.             Can opener.
10.             Essential medicines
11.             Cash and credit cards
12.             Thick ropes and cords
13.             Sturdy shoes

A cyclone is a storm accompanied by high speed whistling and howling winds. It  brings torrential rains.

The word cyclone has been derived from Greek word ‘cyclos’ which means ‘coiling of a snake’. The word cyclone was coined by Heary Piddington who worked as a Rapporteur in Kolkata during British rule. The terms "hurricane" and "typhoon" are region specific names for a strong "tropical cyclone". Tropical cyclones are called "Hurricanes” over the Atlantic Ocean and "Typhoons” over the Pacific Ocean.

A cyclonic storm develops over tropical oceans like the Indian Ocean and Bay of Bengal   and the Arabian Sea. Its strong winds blow at great speed, which can be more than 118  kilometers per hour.

When a cyclonic storm approaches, the skies begin to darken accompanied by lightening  and thunder and a continuous downpour of rain.

The frequencies of cyclonic storms crossing different coastal states of India during 1891-2006 are shown in the figure below. The frequency of severe cyclonic storms is maximum for Andhra Pradesh while that of cyclone is maximum for Orissa. Considering west coast only, Gujarat is most vulnerable.

The death toll in the infamous Bangladesh Cyclone of 1970 has had several estimates, some wildly speculative, but it seems certain that at least 300,000 people died from the associated storm tide [surge] in the low-lying deltas.

The dangers associated with cyclonic storms are generally three fold.

1. Very heavy rains causing floods.

2. Strong wind.

3. Storm surge.

The wind speed may be as high as 300 kmph.

Storm Surge is an abnormal rise of sea level as the cyclone crosses the coast. Sea water inundates the coastal strip causing loss of life, large scale destruction to property & crop. Increased salinity in the soil over affected area makes the land unfit for agricultural use for two or three seasons.

Storm surge depends on intensity of the cyclone (Maximum winds and lowest pressure associated with it and Coastal bathymetry (shallower coastline generates surges of greater heights).

The on shore wind gives rise to storm surge. Thus the forward right sector of a storm gives rise to storm surge.

The storm tide is the combination of storm surge and the astronomical tide.

Entire Indian coast can be categorized into 4 zones

• Very high risk zones (Surge height > 5m)
• High risk Zone (Surge height between 3-5m)
• Moderate risk zone (Surge height between 1.5 to 3m)
• Minimal risk zone ( Surge height < 1.5m)

When the speed of movement is 10-14 kmph, it is called as slow moving cyclone. It is called as moderately moving cyclone, if the speed of movement is 15-25 kmph. If the speed of movement is more than 25 kmph, is called as fast moving cyclone.

Warnings are issued for general public, fishermen, farmers and different categories of users such as central and state government officials responsible for disaster mitigation and relief, industrial and other establishments located in the coastal areas, ports, coastal shipping, railways, aviation, transport, communication and power authorities.

It is the point within the earth from where seismic waves orignate. Focal depth is the vertical distance between the hypocentre and epicentre.

            Vulnerability is the degree of damage caused by various levels of loading. The vulnerability may be calculated in a probabilistic or deterministic way for a single structure or groups  of structures.

The phenomenon Tsunami is a series of traveling ocean waves of extremely long length generated primarily by earthquakes occurring below or near the   ocean floor;

•           A tsunami is a series of waves with a long wavelength and period (time between crests). Time between crests of the wave can vary from a few minutes to over an hour. 

•           Tsunamis are often incorrectly called tidal waves; they have no relation to the daily ocean tides. 

•           Tsunami (soo-NAH-mee) is a Japanese word meaning harbour wave.

•           Tsunamis can occur at any time of day or night.

•           Tsunamis are generated by any large, impulsive displacement of the sea    bed level.

•           Earthquakes generate tsunamis by vertical movement of the sea floor. If the            sea floor movement is horizontal, a tsunami is not generated. Earthquakes of M > 6.5 are critical for tsunami generation.

•           Tsunamis are also triggered by landslides into or under the water surface,   and can be generated by volcanic activity and meteorite impacts.

•           On the average, there are two tsunamis per year in the Pacific Ocean           somewhere, which cause damage near the source.

•           Approximately every 15 years a destructive tsunami occurs in Pacific.

•           The destructive tsunami on Dec 26th, 2004 on the Indian Coast interms of its          impact seems to have occurred for the first time in the history.

•           Tsunami velocity is dependent on the depth of water through which it travels          (Velocity equals the square root of water depth h times the gravitational             acceleration g, that is V =√g h).

•           Tsunamis travel approximately at a velocity of 700 kmph in 4000 m depth of           sea water. In 10 m of water depth the velocity drops to about 36 kmph.

            For example, the tsunami from Sumatra coastal earthquake travelled to       Tamil Nadu coast in about two hours.

            Even on shore tsunamis speed is 35 – 40 km/h, hence much faster than a   person can run.