In my project I will study Mitigation Strategies of Earthquake with specific reference to the Indian subcontinent. Through my research I want to learn about, What are Earthquakes and what causes them?
Which are the earthquake prone regions of India and what are the major earthquakes that have occurred in India? What is Seismic Zoning?
What are the mitigation strategies of an earthquake?
The research methodology that I will be using to write this paper is to read and analyse books and scholarly articles on the topic from reliable sites on the internet. I will be using diagrams and charts to help understand the topic in a better way.
The National Earthquake Information Centre records around 50 earthquakes per day or around 20,000 earthquakes per year.( http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php) Of these an earthquake of intensity over 6.0 on the Richter scale is considered large and can cause immense damage to human life and property. In an article written in 2008, Professor C. Ghosh from the National Institute of Disaster Management said that in the last 20 years 8 major earthquakes have occurred in India resulting in 25000 deaths. And this does not include the recent earthquake which happened on the 18th September 2011 at Gangtok, Sikkim which measured 6.8 on the Richter scale resulting in many deaths and immense damage to buildings and roads. http://www.thehindu.com/news/national/article2479511.ece). A few days before the earthquake at Sikkim, Delhi and its Satellite towns were jolted by an earthquake of medium intensity which made people run out of their homes into the open. The intensity of the earthquake was 4.2 with its epicentre at Sonepat, Haryana. (http://www.thehindu.com/news/national/article2433325.ece). It is said that 90% of the casualties during earthquakes are due to collapse of buildings which do not have any earthquake resistant features. Further it is a known fact that with the present state of scientific knowledge one cannot predict the time, date or place of occurrence of an earthquake. http://earthquakescanada.nrcan.gc.ca/info-gen/faq-eng.php#predicted. This raises the question, ‘How can we mitigate the effects of an earthquake so as to limit the loss of life and property?’. This paper attempts to bring out some of the mitigation strategies of earthquake with specific reference to the Indian sub-continent.
Earthquake and the Indian subcontinent:
Before we discuss about mitigation strategies it is imperative that we understand why an earth quake occurs and the various earthquake prone zones in India. Earthquakes & its Causes:
Earthquake is one of the most destructive disasters that occur when the tectonic plates contact each other, stress arises in the crust. This stress can be classified into three types according to the type of movement along the plate’s boundaries: (a) Divergent- Where new crust is generated by the pulling away of the plates from each other. (b) Convergent-where the crust is destroyed as one of the plates dives under another (c) Transformational- Where crust is neither produced nor destroyed as the plates slide horizontally past one another. The rates of plate movements range from about 2 to 12 centimetres per year. Sometimes, tremendous energy can build up within a single, or between neighbouring plates. If the accumulated stress exceeds the strength of the rocks making up these brittle zones, the rocks can break suddenly, releasing the stored energy as an earthquake. (http://earthquakescanada.nrcan.gc.ca/info-gen/faq-eng.php#predicted)
The energy released during an earthquake is known as the magnitude of the earthquake and is measured by using a Seismograph. Earthquakes can be classified according to their magnitudes as given in the tabular column below:
Classification of magnitude
| Magnitude up to 4.9
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