Teaching Environmental Studies Disasters Notes - Disaster

 

Disaster  

 

A disaster is a sudden, calamitous event that seriously disrupts the functioning of a community or society and causes human, material and economic or environmental losses that exceed the community's or society ability's to cope using its own resources.

 

10.1 Types of Disaster

 

Disaster can be divided into two types on the basis of origin: Natural disaster and human originated disasters.

 

10.1.1 Natural Disaster

 

These are major adverse event resulting from natural processes of the Earth e.g. floods, hurricanes, tsunamis volcanic eruption earthquakes truncations and other logic processes.

The severity of a disaster is measured in lives lost, economic loss and the ability of the population to rebuild.

Some natural disasters are as follow

 

Earthquake

 

These are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two plates are rubbing each other earthquake occurs. Earthquake is measured in Richter scale (discovered by Dr Charles Richter in 1930). Following are the impact of earthquake

 

Impact on Human An earthquake may cause injury and loss of life, road and bridge damage, general property damage. And aftermath may bring diseases, lacks of basic necessities, mental consequences such as panic attacks, depression etc. In Nepal April 2015, earthquake killed nearly 9000 people and injured nearly 22000. It was of 7.8-8.1 on Richter scale.

 

Shaking and Ground Rupture This way result more of less severe damage to the buildings and other rigid structures. The severity is depend upon the complex combination of the earthquake magnitude and distance from the epicentre. Earthquake on 26th January, 2001 occurred in Kutch District of Gujarat, it was India's 52nd Republic Day at 8:46 AM. It is also called as Bhuj-earthquake. Magnitude of the earthquake was 7.7 on Richter scale. Earthquake magnitude higher than 6 on Richter scales are very dangerous

 

Landslides

 

Earthquake can produce slope instability leading to landslides.

 

Tsunami Tsunamis are long wavelength, long-period sea waves produced by the sudden of abrupt. Movement of large volumes of water including when an earthquake occurs at sea.

Generally, Tsunami arises at pacific ocean, where

Alaska, Japan, Philippines other islands of South-East Asia, Indonesia and Malaysia included.

 

Tsunami also occur in Myanmar, Sri Lanka and other coastal areas of India in Indian Ocean. On 26th

December, 2004 a magnitude 9.1 earthquake whose epicentre was located in Indonesia's, Sumatra coast recorded most powerful tsunami in history. It killed around 230000 people of 14 countries. India was also effected on the Andaman and Nicobar Islands and Southern coastal areas.

 

Volcano

 

It is a circular vent or fissure in Earth's crust through which lava, ash, rock and gases erupt. Volcanoes are found u three states extinct, dormant and active.

These are as follow

(i) Extinct Volcano An extinct volcano will never erupt again e.g. Mt Kulal in Kenya, Mt Buninayong in Australia.

 

(ii) Dormant Volcano An dormant volcano has not erupted in last 2000 years e.g. Kilimanjaro

(Tanzania); Mavna Kea (Hawaii); Mt Hood (US); Mt Ararat (Turkey).

 

(iii) Active Volcano An active volcano has erupted recently and is likely to erupt again e.g. Kilanea

(Hawaii), Mt Etna (Italy); Nyamuragira (Congo); Mt Fuji (Italy).

 

·                     'Ring of Fire' It is a volcanic chain surrounding the 'Pacific ocean'. It is famous for its regular earthquake and volcanic activity. More than half of the world's active volcanoes above sea level form part of the ring.

 

Reason of Volcanic Eruption

Volcanic eruption is not related with any artificial, seasons, this only result of plate movement and other related reasons like magma rises through cracks of Earth's crust.

 

Cyclone

It is a large scale air mass that rotate around a strong centre of low atmospheric pressure. \[30{}^\circ \] North and \[30{}^\circ \] South is the region of cyclone. A cyclone can be wide spread upto 500 to 1000 km and height of upto 12-14 km. A fully nature cyclone develops a calm centre, called eye of the cyclone. Diameter of eye is about 10-50 km. Eye is a cloud-free zone.

 

On the Basis of Location

 

Hurricane storm occurs in the Atlantic ocean and

North-Eastern Pacific ocean, Typhoon in North-Western Pacific Ocean and Cyclone in South Pacific or Indian Ocean.

 

Effects of Cyclone

 

The destruction from a tropical cyclone depends mainly on its intensity, its size and its location.

The main effects are : cloud, heavy rain, strong wind, flooding large storm and tornadoes.

 

There is high rise in sea-line hence sailors have risk of life. These cyclone show most effect in

Odisha, Andhra Pradesh and Bengal.

 

Flood

Usually, dry land submerges with over flow of water for several day is called flood. Sometimes water resources (river, lakes and pond receives too much extra water, either from heavy rain or other natural disasters. North-Indian plains are divided into 3 broad division for flood prone areas. These are as follow

 

Ganga Basin Besides Ganga, rivers like Sharda, Rapti, Gandak and Ghagra causes flood in Eastern part of UP Yamuna cause flood in Haryana and Delhi. Bihar experience flood due to river Burhi, Bagmati, Gandak, Kamla. In West

Bengal Mahananda, Bhagirathi, Damodar etc cause flood.

 

Brahmaputra and Barak Basin Brahmaputra and Barak river if get surplus water cause flood.

North -Eastern states like West Bengal, Assam and Sikkim are affected with these rivers.

 

Central India and Deccan Rivers Basin

In Odisha, rivers, Mahanadi, Baitarni and Brahamani cause flood. Southern and Central India observe flood by Narmada, Godavari, Tapi, Krishna and Mahanadi due to heavy rainfall. Cyclonic storm of Godavari, Mahanadi, Krishna cause flood in coastal regions of Andhra Pradesh, Odisha and Tamil Nadu.

 

Drought

 

It is a situation when the mean annual rainfall is less than 75% of the normal rainfall. A severe drought when the deficiency of rainfall exceeds

50% of the normal rainfall and moderate drought when the deficiency of rainfall is between 25-50% of the normal rainfall.

 

Drought in India

 

There is a history of drought in India. In India between 110 years (1877 to 1987) 23 drought faced by Indian population. In general about 16% area an 12% population is affected by drought every year according to data.

 

10.12 Human Originated Disaster.

 

Such type of disaster are the consequences of technological hazards, e.g. fires, transport accidents, industrial accidents, oil spills and nuclear explosions and radiation. War and deliberate attack can also included in this category.

 

Nuclear and Radiation Disaster

 

It is an event that has led to significant consequences to people, the environment or the facility; not led by nature but by human activities.

1st nuclear reactor was constructed in 1954 e.g. Major nuclear accident by which radio activity are released which impact on human very adversely.

 

Nuclear War

 

·                     In World War II, by the order of President of US 'Truman', US dropped nuclear weapons on Japanese cities-Hiroshima and Nagasaki on 6th and 9th August, 1945.This bombings killed at least 129000 people, it is only use of nuclear weapons in war history.

·                     About IS km height long ashes and fumes arises by nuclear bornb. The bomb dropped on Hiroshima was known as Little Boy, about 350000 population was live in Hiroshima at the time of bombing. Between 90000 to 166000 people are believed to have died from the bomb. The bomb dropped on Nagasaki was named as Fatman.

 

Nuclear Accidents

 

·                     Fukushima Daiichi On 11th March, 2011, this nuclear power plant got nuclear accident result of this, there was an explosion and radiation leak.

This was the result of 9.0 earthquake and major

Tsunami. This accident was of level 7 of radiation damage.

Now-a-days this plant is fully diminished.

 

·                     Three Miles Island This is a nuclear generating station in Eastern Pennsylvania, Three Mile Island accident was caused by a nuclear meltdown on 28th March, 1979 in reactor number 2. The accident was rated a five on the seven-point International Nuclear event scale. No casuality observed but 140000 people had left the area.

·                     Tokaimura Nuclear Accidents The accident was due to no proper qualification and training given to the workers. Two worker were dead while 100 worker was injured.

·                     Carnobyl Nuclear Disaster This catastrophic nuclear accident occurred on 26th April, 1986.

This plant was situated at the border of Belarus and Ukrain. There was a destructive steam explosion and a subsequent open-air graphite fire which persist for 9 days.

Radiation emitted in this accident was 100 times more than the Hiroshima and Nagasaki attacks. According to data provided by Russian government, 50 people were dead while according to International Nuclear Energy Agency 1000 people were dead and radiation level was of 7.

 

Industrial Disaster

Bhopal Gas Tragedy This was considered as the world's worst industrial disaster. It occurred on the night of 2nd-3rd December, 1984 at Union

Carbide India Limited, pesticide plant in Bhopal.

There was leakage of Methyl Isocyanate (MIC) gas and other gases resulting around 500000 people exposed.

 

Noise Pollution

'Sound' is a necessary feature of our life. A low sound is pleasant where as a loud sound-is disturbing and commonly referred as 'noise'.

Noise is 'unpleasant and unwanted sound'. It can be recorded in Decibel meter. Different Decibel (dB) units are near total silence 0 dB. A whisper

15 dB, Normal conversation 60 dB, Car horn 110 dB, A rock concert/jet engine 120 dB, A fire cracker/gunshot 140 dB. Any sound above 85 dB can cause hearing loss.

 

Green Muffler

With the help of this technique, we can control noise pollution by planting green plants, normally 4-5 rows of plants are grown near noisy areas like road sides and industrial areas so that these trees can create some obstruction for noise to reach to residents.