A subduction process similar to the one that caused the Ecuadorean quake is happening under the Himalayan region as well, where the Indian plate is getting inside the Chinese landmass.
This northward push has been creating a huge amount of tectonic strain in the region, making it particularly prone to earthquakes.
Scientists believe there is so much energy stored in the area that an earthquake of magnitude greater than 8, possibly even 9, would be needed to release it. This earthquake can come at any time.
The Nepal earthquake was a result of this same process, but it was relatively weak in magnitude.
Interestingly, historical data from the US Geological Survey shows that on an average only one earthquake of magnitude 8 or above, called as ‘great earthquakes’, takes place in a year anywhere in the world. This year there hasn’t been a 8-plus quake so far.
There have been aberrations. The year 2007, for example, witnessed as many as four 8-plus earthquakes – in Kuril Islands in north Pacific, Soloman Islands near Australia, central Peru, and in Sumatra in Indonesia. The years 1920, 1923, 1946, 1960 and 1995 each had three of these big events.
On the other hand, in recent memory, 2002, 2008 and 2013, did not have any 8-plus earthquake. Still, the period after 2000 has been one of the most frequent for ‘great earthquakes’. As many as 20 of these events have happened in these 15 years.
The frequency of earthquakes every year increases exponentially as we look at smaller magnitudes. Earthquakes of magnitude between 7 and 7.9 happen 15 times on an average every year, while 134 instances of earthquakes between 6 and 6.9 are recorded every year. Read more