Earthquakes
Earthquakes are mighty killers. About 15,000 people are killed by them every year and more than 100 million people have lost their life due to earthquakes in the history of mankind. Earthquakes have the power to uproot trees and send them crashing into buildings. They can trigger landslides and avalanches and cause fires, flooding and tsunamis that cause further devastation.
Any one who has visited California in USA will tell you what a beautiful State it is . But it is one of the most earthquake prone regions in the world. This is because a series of cracks in the earth crust run parallel to its coast. These are called faults. They are the places where the slabs that make up the earths crust called the tectonic places rub alongside each other. The tectonic pates move continually and this movement causes tremors along the fault lines.
The Indian Tectonic Plate
The India or Indian Plate is a tectonic plate that was originally a part of the ancient continent of Gondwanaland from which it split off, eventually becoming a major plate. About 50 to 55 million years ago, it fused with the adjacent Australian Plate. It is today part of the major Indo-Australian Plate, and includes the subcontinent of India and a portion of the basin under the Indian Ocean.
About 90 million years ago, subsequent to the splitting off from Gondwanaland, the India Plate split from Madagascar. It began moving north, at about 20 cm/yr and began colliding with Asia between 50 and 55 million years ago. During this time, the India Plate covered a distance of 2,000 to 3,000 km , and moved faster than any other known plate. In 2007, German geologists determined that the reason the India Plate moved so quickly is that it is only half as thick as the other plates which formerly constituted Gondwanaland.
The collision with the Eurasian Plate along the boundary between India and Nepal formed the orogenic belt that created the Tibetan Plateau and the Himalaya Mountains, as sediment bunched up like earth before a plow.
The India Plate is currently moving northeast at 5 cm/yr, while the Eurasian Plate is moving north at only 2 cm/yr . This is causing the Eurasian Plate to deform and the India Plate to compress at a rate of 4 mm/yr.
The seismic zone of India is depicted in the map. It clearly shows the highest earthquake riskis at the zones close to the Indian Plate.
Himalayas and how it is formed?
The highest mountain range in the world, the snow-capped Himalayas, is an example of a continent-to-continent collision. This immense mountain range began to form when two large landmasses, India and Eurasia, driven by tectonic plate movement, collided. As both landmasses have about the same rock density, one plate could not be subducted under the other. The pressure of the colliding plates could only be relieved by thrusting skyward. The folding, bending, and twisting of the the collision zone formed the jagged Himalayan peaks. This string of towering peaks is still being thrust up as India, embedded in the Indo-Australian Plate, continues to crunch relentlessly into Tibet, on the southern edge of the Eurasian Plate.
Major Earthquakes in India
| DATE | LOCATION | MAGNITUDE | TOTAL DEATH |
| 2004 DEC 26 | OFF WEST COAST OF SUMATRA | 9.3 | 2,25,000* |
| 1897 JUN 12 | SHILLONG PLATEAU | 8.7 | NA |
| 1950 AUG 15 | ARUNACHAL PRADESH-CHINA BORDER | 8.5 | NA |
| 1934 JAN 15 | BIHAR-NEPALBORDER | 8.3 | 10,700 |
| 1941 JUN 26 | ANDAMAN ISLANDS | 8.1 | NA |
| 1819 JUN 16 | KUTCH,GUJARAT | 8 | NA |
| 1905 APR 04 | KANGRA, H.P | 8 | 19,000 |
| 2001 JAN 26 | BHUJ , GUJARAT | 7.7 | 21,000 |
| 1918 JUL 08 | SRIMANGAL, ASSAM | 7.6 | NA |
| 2005 OCT 08 | PAKISTAN | 7.6 | 85000* |
| 1869 JAN 10 | NEAR CACHAR, ASSAM | 7.5 | NA |
| 1943 OCT 23 | ASSAM | 7.2 | NA |
| 1930 JUL 02 | DHUBRI, ASSAM | 7.1 | NA |
| 1885 MAY 30 | SOPOR, J&K | 7 | NA |
| 1956 JUL 21 | ANJAR, GUJARAT | 7 | NA |
| 1999 MAR 29 | CHAMOLI DIST, UP | 6.8 | NA |
| 1988 AUG 06 | MANIPUR-MYANMAR BORDER | 6.6 | 1,000 |
| 1991 OCT 20 | UTTARKASHI, UP HILLS | 6.6 | 2,000 |
| 1967 DEC 10 | KOYNA, MAHARASHTRA | 6.5 | NA |
| 1988 AUG 21 | BIHAR-NEPAL BORDER | 6.4 | NA |
| 1993 SEP 30 | LATUR-OSMANABAD, MAHARASHTRA | 6.3 | 10,000 |
| 1975 JAN 19 | KINNAUR, HP | 6.2 | NA |
| 1997 MAY 22 | JABALPUR,MP | 6 | NA |
* – Death toll is the total include the deaths in other countries in the region.
Mapsofindia Blog 