Disaster Management Science Notes
→ Earthquake: An earthquake is caused by sudden vibrations felt due to shaking of the earth’s surface or ground. The earthquake is caused due to seismic waves. These waves cause movements of the earth’s surface which are perceived as tremors or shaking.
→ The vibrations cause the surface of the earth to go up- down. The resulting shocks and waves formed in the interior of the earth spread on the surface in all directions.
→ The central point of earthquake: The point above the epicentre on the earth’s surface is called central point of the earthquake. In this area there is a major loss as the strong waves reach the epicentre first.
→ Shocks of earthquake:
- Mild: Shocks are in more frequency, but destruction is less.
- Acute or Intensified: Frequency of shocks is much less but major destruction is caused.
→ 12,400 to 14,000 earthquakes occur on the earth per year. Daily there is occurrence of earthquake somewhere on the earth. National Earthquakes information centre has carried out all such observations.
→ Seismograph or Seismometer: Instrument which records the earthquakes.
→ Richter Scale: The mathematical measure to understand the accentuation (intensity) of earthquake.
Causes of an Earthquake
→ Natural causes:
- Volcanic eruption
- Steam formed in the interior of Earth tries to come out on the earth’s surface.
→ Causes due to actions of human beings:
- Underground atomic tests.
- Pressure due to mega-hydroelectric projects and dams.
Effects of earthquake
→ Biological impacts: Wild animals and domestic animals are killed. Loss of life for human beings. Destruction of biodiversity. Ecosystems endangered.
→ Economic Impacts: Economic loss, destruction of infrastructure. Electric poles, pipelines, houses, buildings, roads, railway tracks, etc. are completely destroyed. Urban regions may face dangers of fire.
→ Economic Impacts: Economic loss, destruction of infrastructure. Electric poles, pipelines, houses, buildings, roads, railway tracks, etc. are completely destroyed.
→ Geographical impact: Flow of rivers and streams are changed. Tsunami waves are formed. The coastal regions are largely affected due to devastating tsunamis. Level of groundwater table either decreases or increases.
→ Precautions to be taken Dos and dont’s at the time of earthquake:
1. Not to get scared, not to run helter-skelter.
2. Stand silently at one place.
3. Or sit on the ground under a table or other furniture.
4. Wait there till the movement of the earth do stops. Protect your head and face by covering it with folded hands.If outside the home:
1. If travelling in the vehicle, park your vehicle at a safe place and be inside the vehicle.
2. Avoid waiting below tall buildings, trees or electric pole.
|1. Not to use elevator at the time of earthquake.
2. Do not sit in an uncomfortable position for a long time.
3. Do not be motionless for a long time.
4. Short circuit may break into fire therefore do not keep the main electric connections switched on. Turn off the mains.
5. Not to use candles, lantern or matchbox.
6. It may break into fire.
7. Instead use torches.
Earthquake Resistant Buildings:
The Earthquake Resistant buildings are constructed with the idea that even if there is some movement of the earth, the building should not get damaged.
|Some codes of conduct made by Indian Standard Institute||For construction of buildings|
|I.S. 456||Buildings are constructed|
|I.S.1893||Earthquake resistant constructions are performed|
|I.S. 13920||Ductile detailing of reinforced concrete structures subjected to seismic forces.|
Modern equipment that give prior intimation about earthquake: Laser ranging, very long baseline, Geiger counter, creep meter, strain meter, tide gauge, tilt meter, volumetric strain gauge, etc.
→ Types of Fire:
|Types of Fire||Which substances catch fire?||Examples||Method to extinguish fire|
|Class A Fire||Solid substances||The fire of commonly flammable materials such as wood, clothes, coal, papers, etc.||Put out with water by cooling it out.|
|Class B Fire||Liquid substances||Fires caused by flammable liquid substances such as petrol, oil, varnish, solvents, cooking oil, paints, etc.||Fire extinguishers|
|Class C Fire||Gaseous Substances||Fires caused due to acetylene, household gas (L.P.G.).|
|Class D Fire||Chemical substances||Combustible metals like potassium, sodium and calcium react with water at normal room temperature and metals like Magnesium, aluminium and zinc react with water at high temperature. Explosion occurs when these two groups combine with each other.|
|Class E Fire||Electrical||Electrical components, fittings, etc.||Power supply cut off. Non-conductive fire extinguishers like carbon dioxide.|
→ Methods of Fire Extinguishing: Two important aspects of fire control are:
- To stop the fire
- To prevent it from spreading further.
→ Three main methods:
|Cool Out (Use of Water)||Most common and effective method is to use water. Water extinguishes fire and causes cooling. Water is easily available.|
|Supress the fire||Froth like substance, the Fire sand or soil can be used on the fire. Used for extinguishing fire which is caused due to electricity or oil.|
|Keep away Flammable Substances||Stirrup pump is used to spray water in all the directions around the fire, and thus fire is put off.|
→ Precautions and Safety Measures:
- Switching off the gas regulator when not in use or while going out of the house.
- Switch off the electrical appliances when not in use.
- Calling loudly and making others alert so that they can rush for help.
- Call phone no. 101 to get help from fire brigade.
- To learn the use and operation of fire extinguishers.
- To give first aid to the victims and seek medical help as soon as possible.
There are natural cracks and fissures in hard rocks which result into their breaking at the time of heavy rains. The cracks widen due to flowing water which further causes weathering process. The heavy rocks slide on the sloppy region and collapse to the lower side. This is called landslide.
→ Causes of landslide:
- Major natural disasters such as earthquake, tsunami, cloud bursting, cyclone, storms and floods can result into landslide.
- Excessive deforestation and cutting down the trees cause soil erosion leading to landslide.
- Digging done at the time of road constructions, makes the mountains weak resulting into landslide.
→ Effects of landslide:
- Rivers get flooded.
- Rivers change their path.
- Waterfalls are displaced, and they change their original position.
- Artificial reservoirs are formed.
- The trees are uprooted and the plant life in general is destroyed.
- The constructions done on the slope collapse.
- There is large scale loss of life and property as the villages are buried under the debris.
- The debris and rocks on the rail tracks or roads cause suspended traffic.
→ Disaster relief – planning:
Disaster relief plan is specially done to monitor and manage the conditions when disaster strikes. The urgent relief work is necessary during any disasters and hence this kind of preparations are necessary.
→ Work of the institutes that manage the disaster relief:
|National Institute of Seismology||Research work related to earthquakes and allied disaster relief work.|
|Indian Mountaineering Institute||Program to forecast the landslides and its effects.|
|International centre for Integrated Mountain Development.
Institute of Geology and World Geological Forum.
|These International Institutes help the Institutes in India.|