The Himalayan Mountain ranges are largely known as a top destination for trekking because of their pristine peaks and breathtaking views. At the same time this mountain range also happens to be one of the most seismically active regions in the world.
The Himalayan ranges were formed as a result of collision between Indian plate and Eurasian plate (a plate is the outermost layer of the earth with a depth of up to 200 km). The Indian plate is moving under the Eurasian plate at a rate of 4 to 5 centimeters per year, causing an uplift to the Himalayan region . This is what we call subduction of the Indian plate beneath the Eurasian plate makes the Himalayan region so seismically active.
On the morning of April 25 a magnitude 7.8 earthquake struck near Lamjung, with the epicenter between the capital Kathmandu (home to 1.2 million people) and Pokhara, the second largest city.This shallow earthquake, just 15km deep, was the result of a shift (near the main frontal thrust) of the two plates.
Kathmandu sits on a dried-up lake bed with a soft soil, which amplifies the seismic motion and further worsens the situation. The previously largest earthquake in Nepal (Mw –8.2) occurred in 1934 close to Nepal Bihar boundary and caused widespread liquefaction in the state of Bihar in India. Causalities rose above 10,000 in India and Nepal after the quake.
In the coming week there could be aftershocks with magnitude 5 or more, with the chances of aftershocks with magnitude above 6 are more at 60%, according to the U.S. Geological Survey. Tremors were widely felt in neighboring countries including India. The worst affected states in India are Bihar and Uttar Pradesh.
At present the official casualty figure is over 3700,with casualties from India, China and Bangladesh. The figure is expected to rise. Widespread loss of property has been reported from Kathmandu and two of the historic monuments in Kathmandu, the UNESCO World Heritage Sites of Kathmandu Durbar Square and the Dharahara tower, were severely damaged. The earthquake also triggered an avalanche near Mount Everest and many trekkers are feared to be trapped. Moreover, it is estimated that around 300,000 tourists were in Nepal during this time of the year and this will have a huge impact on the tourism industry in Nepal.
The international community has started supporting Nepal in their relief efforts. While this will assist in initial rescue and recovery operations and is highly appreciated, this will not be enough to cover widespread damage (both economic and human losses) in the country or bring it back to a pre-disaster level.
Only a very small fraction of total economic losses is likely to be insured, highlighting the importance of state sponsored or public private partnership in providing insurance solutions to individuals and institutions to be resilient and quickly recover on experiencing such disasters. These solutions need to be supported by strong building codes,enforcements and better urban planning in these high hazard areas. Nepal can learn from other disasters on how to move forward. A good example are the steps taken by New Zealand government in red flagging many of the liquefaction prone areas in Christchurch after the series of earthquakes, which struck the Canterbury region in 2010 and 2011.
If there is such a thing as a silver lining to an event like this, it is about the lessons that can be learned to prevent future catastrophes. This quake provides an opportunity for Kathmandu to rebuild the region with stronger building construction practices able to resist strong earthquakes in the future. It is also a striking reminder to the neighboring countries, particularly India which has grown tremendously in the last few decades. Many of the highly urbanized regions in India, including its national capital region are within the striking distance of a big Himalayan earthquake.Almost all of these cities are built on deep soil basin and induced effects like site amplification and liquefaction will worsen the earthquake effects. Given large inventory of poor quality structures with haphazard development, even a smaller magnitude earthquake will be enough to cause tremendous economic and human losses.
We cannot afford to ignore these risks any longer.
Category: Climate/natural disasters: Disaster risk, Earthquakes