Why is it in the news?
2. The Earthquake killed more than 1666 people and more than 3400 people were injured. 139 people are believed to be missing. Its effect was also felt in the far flung Bangkok, a city in Thailand where more than 10 deaths have been reported. It is believed that more than 10 thousand people would have been killed only in Myanmar. The exact data would come to light when debris is excavated and rescue operations are completed.
3. The earthquake destroyed buildings, drowned bridges and buckled roads across Myanmar with massive destruction in the city of Mandalay.
4. The Government of India launched operation Brahma to provide humanitarian assistance to earthquake affected people. India has dispatched search and rescue teams to Myanmar. The Indian air force carried relief materials to Myanmar. India would also set up a field hospital in the quack hit region.
5. The US, China and other countries also extended help to the quack hit people of Myanmar.
6.It should be noted that more than 20 lakh Indians are living in Myanmar. No casualty of any Indian citizen working in the country has been reported so far. Myanmar needs more help from foreign countries. It is a poor country, having low resources. The rehabilitation of the affected people by the Government of Myanmar itself is beyond its capacity, looking into the magnitude of disasters caused by earthquakes.
Structure of the Earth?
1. In order to understand the causes for the occurrences of the earthquake, it is essential to understand the structure of the Earth.
2. The structure of the Earth consists of four layers. These are crust, mantle, outer core and inner core. Crust has a thickness of 5 km in the Ocean and about 70 km in the Continent.
3. The Continental crust is composed mostly of granite while the oceanic crust is composed mostly of basalt.
4. Mantle has a thickness of 2900 km. It is composed mostly of magnesium and iron. It has two layers- the upper mantle consists of a lithosphere which is rigid and an asthenosphere which is semi-fluid. Lower mantle is more rigid due to high pressure. The temperature ranges from about 500°C near the crust to 4000°C near the core. The difference between the temperatures creates convection currents in the mantle, thereby, driving plate tectonics.
5. Outer core has a thickness of 2200 km and is composed of liquid iron and nickel. Its temperature varies between 4000°C to 5700°C. The movement of liquid matter generates the Earth’s magnetic field. The inner core has a thickness of 1220 km. It is composed of solid, iron and nickel. Its temperature goes to 600°C. Despite high temperatures , intense pressure keeps the inner core solid.
Lithosphere
1. It is composed of the crust and the uppermost part of the mantle. It is solid and brittle in nature and is divided into large rigid pieces called tectonic plates. Its thickness varies from 100 km beneath the oceans and 200 km under continents.
2. Lithosphere is solid and rigid compared to the underlying asthenosphere which is semi-fluid. Because of the semi-fluid asthenosphere and convection currents, the lithosphere moves. Lithosphere is broken into several tectonic plates. The interactions between lithospheric (tectonic) plates cause earthquakes, volcanic activity, high mountain and ocean tanks formation.
3. There are seven major lithospheric (tectonic) plates in the world. These are Pacific, North American, South American, African, Eurasian, Antarctic, Indo Australian plates.
4. Apart from major tectonic plates, there are various minor tectonic plates like Arabian (Arabian peninsula), Caribbean (between North and South America), Cocos (Off the West Coast of Central America), Nazca (Off the West Coast of South America), Philippines Sea plate (East of Philippines), Scotia plate (situated between South America and Antarctica), Juan de fuca plate (Off the Pacific Northwest Coast of North America), Indian (Part of Indo-Australian plate), Somali (along the East African rift), Caroline (Western Pacific Ocean), Okhotsk (part of the North West Pacific including parts of Russia and Japan), Yangtze (parts of China), Amurian (Eastern Asia including parts of Russia and China), Sunda (includes parts of SouthEast Asia, Java, Sumatra and Borneo bounded by Eurasian, Australian, Philippine and Indian Plates). These plates interact with the major plates causing earthquakes, volcanic eruptions and the formation of mountain ranges.
How Earthquakes occur?
1. Movement of the plates - The tectonic plates move continuously towards each other. If one tectonic plate crashes another plate it is called convergent boundary. The heavier plate is subducted below the lighter plate, thereby, causing release of energy and therefore, the trembling of earth called earthquake. When two tectonic plates move apart it is called divergent boundary. It causes a fault line and this fault line releases energy on account of stress on the Earth’s crust leading to earthquakes.
Thirdly, when one tectonic plate slides past another tectonic plate,it is called the transform boundary. And if some part of the plate is struck with another part of the plate, it leads to the shaking of the earth. The earthquake in Syria and Turkey in 2023 was caused by the sliding past one plate by another plate.
2. Earthquakes are also caused by volcanoes in areas having crustal weaknesses.
3. In the areas of intense mining activities, roofs of the underground mines collapse causing minor tremors.
4. Nuclear explosion and implosion further cause earthquakes.
5. It is also caused where large dams or reservoirs have been built.
Why did the Earthquake occur in Myanmar on 28th March 2025?
1. The epicentre of the earthquake was at Sagaing fault line. It is a right lateral strike slip fault in Myanmar where the primary movement is horizontal. It means the blocks of the earth crust move side by side and parallel to the faultline rather than up or down. The displacement is caused by shearing forces.
It runs in a north-south direction and is approximately 1200 km long. This fault line forms the boundary between the Burma microplate, the part of Sunda plate and the Eurasian plate. It accommodates the northward movement of the Indian plate relative to the Sunda plate. The tectonic interactions result in significant stress accumulation along the faultline. When this stress exceeds the frictional resistance along the fault, it releases seismic energy causing an earthquake.
Distribution of Earthquake prone zones of the earth
1. Circum Pacific seismic belt - Also called ring of fire along the pacific ocean rim having more than 81% earthquakes.
2. Alpine continental belt - It stretches from Europe to Sumatra via the Mediterranean , the Himalayas and into the Atlantic Ocean. This belt accounts for about 17% of the world’s earthquakes.
3. Mid Atlantic Ridge - A divergent plate boundary called the mid Atlantic ridge is mostly underwater.
Distribution of Earthquake prone zones in India
India has been divided into four seismic zones :
1. Zone V consists of parts of Kashmir Valley, Western Part of Himachal Pradesh, Eastern Part of Uttrakhand, Kutch in Gujarat, Part of Northern Bihar, all North Eastern States and Andaman Nicobar islands.
2. Zone IV consists of Ladakh, remaining parts of J & K, Himachal Pradesh and Uttarakhand, Delhi, some parts of Haryana, Punjab, Sikkim, Northern Parts of Uttar Pradesh , Bihar ,West Bengal, some parts of Gujarat, Maharashtra and Western Rajasthan.
3.Zone III includes states of Kerala, Goa, Lakshadweep islands, parts of Uttar Pradesh and Haryana, remaining parts of Gujarat and Punjab, parts of West Bengal, Western Rajasthan, Madhya Pradesh, remaining part of Bihar, Northern Part of Jharkhand and Chhattisgarh, parts of Maharashtra, Odisha, Andhra Pradesh, Telangana, Tamil Nadu and Karnataka.
4. Zone II includes the remaining parts of Rajasthan, Uttar Pradesh, Gujarat, Haryana, Madhya Pradesh, Maharashtra, Odisha, Andhra Pradesh, Telangana, Karnataka and Tamil Nadu.
5. Approximately, 11% area of the country falls under Zone V, 18% in Zone IV, 30% in Zone III and the remaining in Zone II. Thus, a total 59% of the landmass of India is prone to earthquakes of different intensities.
Effects of Earthquakes
1. Tremors of grounds
2. Landslides and mudslides
3. Soil liquefaction
4. Ground Displacement
5. Floods from dam failure
6. Structure collapse
7. Tsunami
8. Falling objects/skyscrapers
9. Fire
10. Differential ground settlement
11. Avalanches
How to mitigate devastation caused by earthquakes?
1. Earthquake resistance construction - Houses/ buildings should be constructed in such a way that they can withstand seismic forces.
2. Implementing and enforcing strict building codes that require earthquake resistant design.
3. Site selection and foundation - Avoiding building on loose soils or clay that can amplify seismic waves. Avoiding construction near fault lines, unstable soils and areas prone to liquefaction.
4. Early warning system through television, radio and mobile alerts so that people can take protective measures.
5. Rapid response and recovery - Quick response and mobilising the resources can save lives trapped in debris.
6. Preparedness - rescue and quick response teams should be prepared in advance. These teams should be regularly trained. Ensuring essential services like hospitals, emergency response centres and utilities to respond to the disaster.
7. Public education - Educating communities about the earthquake risks can reduce panic and improve response during the disaster.
8. International cooperation and research - Sharing knowledge, technology and resources with neighbouring countries and international organisations for reduction of earthquake risk.
9. Research and innovation - Investing in research to improve understanding with regard to seismic hazards and developing new technologies for earthquake resistant construction.
10. Retrofitting - Strengthening existing buildings and infrastructure to improve their ability to withstand earthquakes.
11.Implementing land use policies that restrict development in high risk areas and promote open spaces that can serve as evacuation zones.
12. Continuously updating maps pointing out seismic hazards to guide urban planning and infrastructure development.
Conclusion
1. Earthquakes cannot be prevented because they are natural calamities. But systematic earthquake resistant construction designs and preparedness in advance can go a long way in mitigating the devastation caused by the earthquake disaster.
2. The quick response in evacuating the quake hit areas and removal of debris to save people trapped therein would further reduce the magnitude of disaster.
3. The international help and coordination between different agencies would further help in speedy rehabilitation of quack hit people.
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