EARTHQUAKE, ITS REGIONS OF RISK ZONES, PREDICTIONS AND RISK REDUCTION MEASURES IN INDIA: AN OVERVIEW
Dr. Sanjay Singh Pathania
(Associate Professor in Geography), Government Degree College Dharmshala, Distt. Kangra H.P.(176215)
Man has been facing Disasters since the dawn of civilization. The earth has been undergoing various changes; both slow and catastrophic from the beginning time.
Extreme form of hazard leads to disaster.
Hazard may be defined as “a dangerous condition or event, that threat or have the potential for causing injury to life or damage to property or the environment.”
Hazards that cause great loss to human life and economy are known as Disaster.
Disaster (French word des meaning
‘bad’ and aster meaning ‘star’) is a natural or manmade event which results in wide spread loss of life and property. It is a catastrophic situation in which the normal patterns of life have been disrupted and extraordinary emergency interventions are required to save and preserve human lives and the environment. “It is a serious disruption of the functioning of society, causing widespread human, material or environmental losses which exceed the ability of the affected society to cop using its own resources”.
United Nation defines disaster as
“..The occurrence of a sudden of major misfortune which disrupts the basic fabric and normal functioning of a society or community”.
Classification of disaster:- Disaster are generally classified on the basis of their origin.
1. Tectonic (Earthquakes, volcanoes) 2. Topographical (Landslides,
avalanches )
3. Meteorological (Hurricanes, Cyclones, Tornadoes, Floods, Droughts )
4. Infest (Locust invasion of crops, epidemics)
5. Human (Industrial accident, nuclear bombs)
Some disasters are rapid and occur without any warning. They leave a trail of destruction with in a short time.
Very little precaution can be taken to save lives and property in such disasters.
Disaster are unevenly distributed with respect to time and space according to
South Asia Disaster Report 2010 “The year 2010 witnessed an overall increase in the occurrence of natural disasters around the world. There are 373 disaster events that affected a total of 207 million people and 2,96,800 people died in natural disasters during the year 2010,out of which 2,22,500 alone perished due to Mw 7.9 earthquake in Haiti,55,739 persons lost their lives due to forest fire and heat wave in Russia while Mw 6.9 earthquake in China killed 2968 people . Among the south Asian countries Pakistan witnessed a flood that killed more than 2100 people and caused extensive damage to the houses, infrastructure and agriculture in Pakistan.
1 IN INDIAN CONTEXT:
Because of its sub-continental dimensions, geographical situation and behavior of monsoon, India is exposed to various natural or manmade disasters like drought, Flood, Cyclone, Earthquake, etc. year after year”. The terms like earthquake prone, flood prone and drought prone are used to describe the distributional effects of the concerned hazards. The main natural disaster in India are caused by earthquakes Floods and Cyclones. Since the beginning , they have been causing heavy losses of life and property, forcing man to learn and live with natural calamities. It is estimated that 55 % of our landmass is prone to earthquakes of various intensities. i.e.
Seismic Zones III – IV, 5% to floods ,7% to cyclones and 70% cultivable area is prone to drought. Seismically, India is very active since years. Earthquake is a violent tremor in the earth’s crust, sending out a series of shock waves in all directions from its place of origin. For example:- If you through a stone in a pond of still water, a series of concentric waver are produced on the surface of the water.
These waves spread out in all direction from the point where the stone strikes the water. Similarly any sudden disturbance in the earths crust may produce vibration
in the crust which travel in all direction from the point of disturbances. It is one of the worst natural calamities which turn into disaster causing widespread destruction and loss of human lives.
Earthquake’s Magnitude and Intensity; These are two ways of measuring the strength of an earthquake.
It is determined by the use of Seismograph, and instrument which continuously records ground vibration. It is measured on the Richter Scale and was developed by Charles Francis Richter in 1935.Richter scale is the most popular and widely used for expressing the intensity of an earthquake. The intensity or destructive power of an earthquake is an evaluation of the severity of ground motion at a given location. It is described in terms of damage caused to buildings, dams, bridges etc. The intensity of an earthquake is measured by Modified Mercalli (MM scale) developed by an Italian Seismologist Mercalli in 1902 and modified by Wood and Newman in 1931.
Causes of Earthquakes in India;
There are several causes of earthquakes but nearly 95% of such disaster occur at the plate boundaries, and the earthquake generating in this way are most damaging.
Indian Plate:- This plate extends from Himalaya beyond the Andemans and Java, Sumatra to Australia. It is moving in the north-north east direction at an average velocity of about 5 cm per year. It encounters the adjacent plates in Myanmar-Andaman Sumatra region in the east, Himalayan foothills in the north and Suleman ranges of Pakistan in the west. Great earthquakes in Shillong (1897), Kangra (1905), Bihar Nepal (1934), Assam (1950) and Muzaffarabad in POK (2005) have occurred on the northern boundary of Indian plate which is underthrusting the Eurasion plate.
Intraplate Tectonics:- Seismicity of the Indian Plate assumed more importance after the occurrence of earthquakes in the Peninsula. The major earthquakes in the peninsular India are those of Broach (1970), Latur (1993), Jabalpur (1997) and Bhuj (2001). The intra-plate stress is due to the fact that not every part of the plate is similar to these are weak zones and faults. This is known as stable continental
region earthquake. This type of earthquake is rare Latur and Bhuj was of this type. Further research is required to answer such intricate questions.
Reservoir Induced Seismicity (RIS):- The Koyna (1967) could not be explained on the basis of intra-plate tectonic with any degree of satisfaction as a result of which geologist and seismologists turned to the theory of reservoir induced seismicity in a big way. This theory assumes that the load of the huge volume of water impounded can trigger a quake by destabilizing a fault. Based on intensities of earthquake recorded on MM Scale the Indian Standards Institution has published a map of India showing seismic zones.
Zone I - Intensity V or below (Instrument, feeble, slight, moderate.) Zone II - Intensity VI (Strong) Zone III - Intensity VII (Very Strong) Zone IV - Intensity VII (Destructive) Zone V - Intensity IX and above (Ruinous, disastrous, very disastrous, catastrophic)
According to seismologists, one part of India or the other experience one earthquake almost everyday. But most of them are of low intensity, are harmless and go unnoticed. However, major earthquake of higher intensity are strong and result is great loss of life and property. Depending upon the frequency and intensity of the earthquakes the India can be divided into three risk zones.
Himalayan zone:- The areas most prone to earthquakes in India are the fold mountain ranges of the Himalayan zone.
They have not yet attained isostatic equilibrium and are still rising. The region along the Himalaya where two plates meet is highly earthquake prone. This is known as the zone of maximum intensity. Indian plate is pushing in the north and north- east direction at an annual rate of 5 cm subducting the Eurasian plate along the Himalayas. The states of J & K H.P., Uttaranchal, Bihar, Nepal Border and the north-eastern states fall in this zone.
The Indo-Gangetic Zone:- To the south of Himalayan zone and running parallel, it is the Indo-Gangetic zone. Most of the earthquake in this area are of moderate intensity of 6 – 6.5 Richter Scale and are
more harmful due to high density of population.
The Peninsular zone:- This area has presumably remained a stable landmass and only few earthquakes have been
experienced in this region .This region is called zone of minimum intensity. But severe earthquakes of Koyna, Latur and Jabalpur have raised doubts about the seismic stability of this landmass.
Earthquakes Regions and occurrence in India
India has very long history of earthquakes occurrences. The most vulnerable areas according to the present seismic zone map of India are:
1. Kashmir and Western Himalayas:- This region covers the states of J&K, HP and sub-mountainous areas of Punjab.
2. Central Himalayas:- This region includes Uttarachal , U.P. and sub-mountainous parts of Punjab.
3. Northeast India:- This region comprises the whole northeastern part of the country
4. Indo-Gangetic Basin and Rajasthan:- This region comprises of Rajasthan, plains of Punjab, Haryana, U.P. and West Bengal.
5. Khambhat and Rann of Kachchh.
6. Peninsular India including the Islands of Lakshadweep.
7. The Andaman and Nicobar Islands.
Earthquake occurrence in India (1897-2015)
Sr. No. Seismic Region No of earthquakes of Magnitudes Return Period 5.0-5.9 6.0-6.9 7.0-7.9 8.0+
1. Kashmir &Western
Himalayas 25 8 2 2 2.5-3 years
2. Central Himalayas 68 28 4 1 1 year
3. Northeast India 200 128 15 04 < 4 months
4. Indo-Gangetic Basin and
Rajasthan 14 6 - - 5 years
5. Khambhat and Rann of
Kachchh 4 4 1 1 20 years
6. Peninsular India 31 11 - - 2.5-3 years
7. Andaman and Nicobar 90 80 1 1 < 8 months
2 EFFECTS OF EARTHQUAKES
Loss of Life and Property:-There is devastating loss of life and property if the intensity of the earthquake is more than 5 on the Richter scale. Building, roads, railways, bridges, dams suffers severe damage. When Bhuj earthquake struck on 26 Jan, 2001. The towns of Bhuj Bhachau, Anjar, Gandhidam & Ratnal were completely destroyed and property worth Rs. 2000 Crores was destroyed.
Topographical changes:- The main effect of earthquakes on topographical features are seen in the form of offsets along known faults, fissures, elevation and depression of coast, etc. Severe earthquake which struck Uttarkashi in Uttaranchal (1991) caused many cracks and fissures in Varunavat Parvat. This gave birth to landslides which caused heavy damage to Uttarkashi town in the year 2003.
Liquefaction:- Soil liquefaction is a phenomenon where low density saturated sands of relatively uniform size inside the earth start behaving like a jelly with no strength to hold a building up, and the building just sinks or gets tilted. The great Bihar-Nepal earthquake of 1934 produced a belt of slumping extending from Bettiah in north-west of Purnea in the south-east (320 km) surrounding the epicentral tract, in which all buildings were either tilted or sank in soft soil. Even liquefaction of ground was observed during the Bhuj earthquake of 2001.
Building:- Great damage is done to buildings by the earthquakes if they are constructed with brick, mud of timber.
Reinforced concrete buildings suffer least damage. The Muzaffarabad earthquake in oct, 2005 hit Pakistan and India with a magnitude of 7.4 and killed over one lakh persons. Several building collapsed like a pack of cards. Shape of building must be in Geometric shapes such as square of rectangle usually perform better than building in the shape of L, T, U, H, +, O or a combination of these.
Damage to Transport System:- Damage to transport includes highways, railways, airports, marine and river systems, water supply and sewage, fuel and oil, energy transmission and communication systems. The facilities of transport may built either on surface or underground may stop various activities needed for earthquake relief and rescue.
Fire:- There are short circuits, contact of live electrical wires, damage to blast furnaces and other fire related equipment are the major causes of fire.
Flood:- Distortion and displacement of the surface rocks which block the flow of the river. This causes floods in the upper course of the river. Often dams and embankments develop cracks and the course of the river lower than the dam is flooded.
Public Health:- People suffer multiple injuries and many become permanent disable. Many people died due to shock even heart attack.
Civic Services:- Water pipes, sewers, electric, connections, etc. are disrupted.
Economic Activities:- Economic like agriculture, Industry, trade transport and other services may be severely affected.
3 PREDICTION OF EARTHQUAKES If is forecasting of the occurrence of an earthquake in a particular intensity over a specific locality and time limit. Normally prediction is of three types, Long, Medium and Short range prediction. Long range prediction is concerned with for casting the occurrence of an earthquake in a number of years in advance, medium prediction is to be done a few months to a year while short term prediction implies few hours to some days in advance.
Scientist believe that it is possible by monitoring the seismicity caused by natural earthquakes, mining blasts and nuclear tests etc.
1. Unusual Animal Behaviour:- Animals are endowed with certain sensory perceptions which denied to human beings. Some of the animal have much better power of sniffing, hearing, seeing and sensing than the human beings. Unusual behaviour of animals prior to earthquakes received wide publicity after the Haichang earthquake is Liaoning province of China, 4th Feb, 1975 was successfully predicted.
Most animals show restlessness before an earthquake and China was presented a report at the inter – Governmental meeting convened at UNESCO, Paris in Feb, 1976 similar observations about rates were reported at to earlier occasions i.e.
Kanto earthquake of 1929 and Sankriku earthquake in 1933 in
Japan. Even dogs escaped from the city of Talcahuano in Chile before the earthquake struck the city.
Flocks of birds flew inland before the Chilean earthquake of 1822 and 1835. Monkeys became restless a few hours before the Managua earthquake of 1972 in Nicaragua. In Yugoslavia, birds in zoo started crime before 1963 earthquake. Deer gathered and cats disappeared from villages northern Italy two or three before damaging earthquake of 1976. In India unusual behaviour of animals was noticed early in 1892.
During the recent earthquakes of Uttrakashi (1991), Latur (1993), Jabalpur (1997), Chamoli (1999) and Bhuj (2001), there were isolated cases of unusual behaviour of pet dogs. Such abnormal behaviour of the animals is observed during earthquakes of magnitude five or more.
2. Hydrochemical Precursors:- It is observed that concentration levels of dissolved minerals and gaseous component remained almost constant during seismically in active period. But it was notice that the concentration of dissolve minerals and gaseous component in underground water were increased before 2 to 8 days of an earthquake.
After the earthquake, anomalies in concentrations of gaseous and mineral components disappear.
3. Temperature Change:-A rise of temperature by 100 to 150 was reported before the earthquake in Lunglin in China (1976) and Przhebalsk in Russia (1970).
4. Water Level:- There was drastic changes in water level in several wells just before a major earthquake For example:- Nankai earthquake in Japan(1946). Meckering in Australia (1968) Tangshan (1976) and Shayin (1979) in China, 3 to 4 days before an earthquake.
5. Radon Gas:- It is a radioactive gas which is discharged from rock masses prior to earthquake. It is dissolved in the well water and its concentration in the water increases by 15 to 100 percent before 3 to 13 days prior to and earthquake. In 1995 a correlation in radon
anomalies at four sites in Kangra and one site in Amritsar was noticed with the time of occurrence of Uttrakashi earthquake in (1991).
6. Oil Wells:- Large scale fluctuations of oil flow from oil wells prior to earthquakes were reported in Israel, northern Caucasus (Europe) and China.
7. Foreshocks:- Generally major earthquakes are preceded by minor shocks known as foreshocks these shocks provide valuable dues to the occurrence of a strong earthquake.
Some of the earthquakes have been successfully predicted on the basis of study of foreshocks. They have been detected a few days to a month in advance with the help of closely located seismic stations in Himachal Pradesh for several earthquakes like Anantnag (1967), Kashmir (1973), Kinnaur (1975), and even Bhuj Jan, 2001.
8. Changes in Seismic Wave Velocity:- As P,S and L waves originate from the focus of an earthquake. P and S are called body waves because they travel through the inner part of the earth while L wave are known as surface wave because they move along the upper crust of the earth. P and S are faster to reach seismograph first. The time lag between P and S waves is called lead time. Seismologist found that the lead time began to decrease significantly for days and week before the earthquakes but just before the earthquake it the area the lead time back to normal the longer period of abnormality in wave velocity presented a large earthquake.
4 DISASTER MANAGEMENT CYCLE Disaster Risk Management includes sum total of all activities, programmes and measures which can be taken up before, during and after a disaster with the purpose to avoid a disaster, reduce its impact or recover from its losses. The three key stages of activities that are taken up within disaster risk management are:
4.1 Before a disaster (pre-disaster).
Activities taken to reduce human and property losses caused by a potential hazard. For example carrying out awareness campaigns, strengthening the existing weak structures, preparation of the disaster management plans at household and community level etc. Such risk reduction measures taken under this stage are termed as mitigation and preparedness activities.
4.2 During a disaster (disaster occurrence).
Initiatives taken to ensure that the needs and provisions of victims are met and suffering is minimized. Activities taken under this stage are called emergency response activities. After a disaster (post- disaster). Initiatives taken in response to a disaster with a purpose to achieve early recovery and rehabilitation of affected communities, immediately after a disaster strikes. These are called as response and recovery activities.
5 DISASTER RISK REDUCTION 5.1 Preparedness
This protective process embraces measures which enable governments, communities and individuals to respond rapidly to disaster situations to cope with them effectively. Preparedness includes the formulation of viable emergency plans, the development of warning systems, the maintenance of inventories and the training of personnel. It may also embrace search and rescue measures as well as evacuation plans for areas that may be at risk from a recurring disaster.
Preparedness therefore encompasses those measures taken before a disaster event which are aimed at minimizing loss of life, disruption of critical services, and damage when the disaster occurs.
5.2 Mitigation
Mitigation embraces measures taken to reduce both the effect of the hazard and the vulnerable conditions to it in order to reduce the scale of a future disaster.
Therefore mitigation activities can be focused on the hazard itself or the elements exposed to the threat. Examples of mitigation measures which are hazard specific include water management in drought prone areas, relocating people away from the hazard prone areas and by
strengthening structures to reduce damage when a hazard occurs. In addition to these physical measures, mitigation should also aim at reducing the economic and social vulnerabilities of potential disasters.
6 EARTHQUAKES SAFETY MEASURES;
Earthquakes usually give no warning at all. Prepare your family Before the earthquake. Now is the time to formulate a safety plan for you and your family. If you wait until the earth starts to shake, it may be too late. Consider the following safety measures: Always keep the following in a designated place: bottled drinking water, non-perishable food (chura, gur, etc), first-aid kit, torchlight and battery-operated radio with extra batteries. Teach family members how to turn off electricity, gas, etc. Identify places in the house that can provide cover during an earthquake. It may be easier to make long distance calls during an earthquake. Identify an out-of-town relative or friend as your family’s emergency contact. If the family members get separated after the earthquake and are not able to contact each other, they should contact the designated relative/
friend. The address and phone number of the contact person/relative should be with all the family members.
6.1 Safeguard your house
It is much essential to retrofit your house with earthquake-safety measures. As reinforcing the foundation and frame of the building could make your house quake resistant. You may consult a reputed contractor and follow BIS building codes. Kutchha buildings can also be retrofitted and strengthened in such amanner so it will resisted the earthquake.
6.2 During quake
Earthquakes give no warning at all.
Sometimes, a loud rumbling sound might signal its arrival a few seconds ahead of time. Those few seconds could give you a chance to move to a safer location. Here are some tips for keeping safe during a quake. Take cover. Go under a table or other sturdy furniture; kneel, sit, or stay close to the floor. Hold on to furniture legs for balance. Be prepared to move if your cover moves. If no sturdy cover is nearby,
kneel or sit close to the floor next to a structurally sound interior wall. Place your hands on the floor for balance. Do not stand in doorways. Violent motion could cause doors to slam and cause serious injuries. You may also be hit be flying objects. Move away from windows, mirrors, bookcases and other unsecured heavy objects. If you are in bed, stay there and cover yourself with pillows and blankets Do not run outside if you are inside. Never use the lift. If you are living in a kutcha house, the best thing to do is to move to an open area where there are no trees, electric or telephone wires.
6.3 If outdoors:
Move into the open, away from buildings, streetlights, and utility wires. Once in the open, stay there until the shaking stops. If your home is badly damaged, you will have to leave. Collect water, food, medicine, other essential items and important documents before leaving. Avoid places where there are loose electrical wires and do not touch metal objects that are in touch with the loose wires. Do not re-enter damaged buildings and stay away from badly damaged structures.
6.4 If in a moving vehicle:
Move to a clear area away from buildings, trees, overpasses, or utility wires, stop, and stay in the vehicle. Once the shaking has stopped, proceed with caution. Avoid bridges or ramps that might have been damaged by the quake.
6.5 After the quake
Here are a few things to keep in mind after an earthquake. The caution you display in the aftermath can be essential for your personal safety. Wear shoes/chappals to protect your feet from debris After the first tremor, be prepared for aftershocks. Though less intense, aftershocks cause additional damages and may bring down weakened structures. Aftershocks can occur in the first hours, days, weeks, or even months after the quake. Check for fire hazards and use torchlights instead of candles or lanterns. If the building you live in is in a good shape after the earthquake, stay inside and listen for radio advises. If you are not certain about the damage to your building, evacuate carefully. Do not touch
downed power line. Help injured or trapped persons. Give first aid where appropriate. Do not move seriously injured persons unless they are in immediate danger of further injury. In such cases, call for help. Remember to help your neighbours who may require special assistance-infants, the elderly, and people with disabilities. Listen to a battery-operated radio for the latest emergency information. Stay out of damaged buildings. Return home only when authorities say it is safe. Clean up spilled medicines, bleaches or gasoline or other flammable liquids immediately.
Leave the area if you smell gas or fumes from other chemicals. Open closet and cupboard doors cautiously. If you smell gas or hear hissing noise, open windows and quickly leave the building. Turn off the switch on the top of the gas cylinder. Look for electrical system damages - if you see sparks, broken wires, or if you smell burning of amber, turn off electricity at the main fuse box. If you have to step in water to get to the fuse box, call an electrician first for advice. Check for sewage and water lines damage. If you suspect sewage lines are damaged, avoid using the toilets. If water pipes are damaged, avoid using water from the tap. Use the telephone only for emergency calls.
In case family members are separated from one another during an earthquake (a real possibility during the day when adults are at work and children are at school), develop a plan for reuniting after the disaster. Ask an out of state / district relative or friend to serve as the
“family contact”. Make sure everyone in the family knows the name, address, and phone number(s) of the contact person (s).
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