The quake which rocked Nepal on Saturday was the strongest in the region in more than 80 years
GN Bureau | April 27, 2015
What happened in Nepal and how big is the damage?
Seismologists say that the quake happened on what is known as a “thrust fault”. This describes the situation when one piece of the Earth’s crust is moving beneath another piece. In this case, it’s the Indian plate that is moving north at 45 millimetres a year under the Eurasian plate to the north.
United States Geological Survey (USGS) calculations estimate the damage between $100 million and $10 billion. Scientists estimate that more than 105 million people felt moderate shaking during the quake. A UN report says that nearly 6.6 million and 40 percent of the country is affected by the quake.
READ: Nepal earthquake: 3,200 dead and counting
Check here for fatalities and economic losses estimated by the USGS
What are Aftershocks?
An earthquake that follows a large magnitude earthquake called, “main shock” and originates in or around the rupture zone of the main shock. Generally, major earthquakes are followed by a number of aftershocks, which show a decreasing trend in magnitude and frequency with time.
Around 55 aftershocks occured in Nepal in two days after the massive 7.9 magnitude hit the country on April 25.
Why earthquakes occur?
Going by the plate tectonics concept, the Indian plate is moving in a north, north-east direction and colliding with Eurasian plate along the Himalayan mountain range. This collision is responsible for the formation of faults such as boundary thrust, central thrust in and along the Himalayan regions. Almost all the major earthquakes in India and its adjoining region occur along these faults. In brief, earthquakes occur due to forces of geological origin along weak planes called, faults. The earthquakes occurring near plate boundaries such as Himalaya are known as inter-plate earthquakes. Apart from earthquakes from the Himalayan belt, there have been earthquakes of relatively lesser magnitude and lesser frequency in the Peninsular region also. Such earthquakes are known as intra-plate earthquakes.
Nepal earthquake was 7.9, ie. earthquake of great magnitude.
Here is a list of significant earthquakes occurred in and around India
Here is a list of largest and deadliest earthquakes occurred around the world
With inputs from USGS and IMD