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Earthquakes

Earthquake at the top of the world

In the spring of 2015, Nepal and the neighbouring states of India, China and Bangladesh were rocked by a series of powerful earthquakes. The consequences were devastating, especially in the rural district to the northwest of the Nepalese capital, Kathmandu.

02.03.2016

The largest mountain range in the world, the Himalayas, is also home to the highest mountains on the planet. They were formed by the collision between the Indian and the Eurasian continental plates, which began around 65 million years ago. Today, the Indian plate is moving at the rate of around 4 to 5 cm per year in a northerly direction, in the process lifting the Himalayas by roughly one centimetre per year. The forces that occur during this collision sometimes exceed the shear strength of the rocks deep beneath the Himalayas. This produces the sudden displacement of enormous rock masses, which scrape past one another in a matter of seconds, triggering powerful earthquakes in the process.

In the spring of 2015, Nepal and the neighbouring states of India, China and Bangladesh were rocked by a series of powerful earthquakes. The consequences were devastating, especially in the rural district to the northwest of the Nepalese capital, Kathmandu.

Displacement of up to four metres

It was such an earthquake that struck Nepal just before noon on 25 April 2015. It occurred on one of the known major fault lines along the Himalayas, and its magnitude was measured at 7.8, with the epicentre close to the town of Gorkha. Its force was especially strong in the rural district to the northwest of the capital, Kathmandu. Here, displacement of up to 4 metres occurred at a depth of between 10 and 25 kilometres on a rupture face angled to the north. Overall, the rupture face was approximately 100 kilometres long and 80 kilometres wide. In the epicentral area, ground motion was observed up to level IX (of a maximum of XII) on the Mercalli Intensity Scale. In the high mountain regions further north, the quake triggered landslides and avalanches over a wide area, which buried entire villages in the steep valleys that have been carved out of the mountains. Over the following days, there were hundreds of major and minor aftershocks (Fig. 1). The largest, with a magnitude of 7.3, occurred on 12 May, again around lunchtime, approximately 80 kilometres east of Kathmandu. Further damage was caused, and rescue teams from international aid organisations were also caught up in events.

In the spring of 2015, Nepal and the neighbouring states of India, China and Bangladesh were rocked by a series of powerful earthquakes. The consequences were devastating, especially in the rural district to the northwest of the Nepalese capital, Kathmandu.

Many schools destroyed

The earthquakes claimed over 9,000 lives in Nepal, India, China and Bangladesh. There were over 23,000 injured, and more than half a million were left homeless. Despite the fact that Nepal has had a National Building Code since 1994, buildings seldom comply with this construction standard. Building materials (clay, brick, bamboo and wood) are often of poor quality, and the method of construction typically leaves structural weaknesses. Bracing elements are either left out entirely, or the reinforcement measures used are inadequate. There was an alarming number of school buildings affected. A total of 6,000 were significantly damaged or completely destroyed. If the quake had struck on a school day instead of on a Saturday, there would have been many more children among the victims.

Gorkha not a worst-case scenario

Nepal is considered one of the most exposed earthquake regions in the world. Yet even stronger tremors and more violent ground motion than in the Gorkha quake are perfectly possible. The massive deposits of sediment in the southern foothills of the Himalayas (e.g. in the Kathmandu Valley) can even significantly intensify earthquakes at a local level. Seen from this perspective, the Gorkha quake was by no means a worst-case scenario. Historical earthquake catastrophes in the region around Kathmandu are known from the years 1833 (magnitude 7.6), 1934 (magnitude 8.0) and 1988 with a magnitude of 6.9 (see graph on pages 28/29). A total of 10,700 people died in 1934, with around 80,000 buildings destroyed and more than 120,000 damaged. Over 50 years later, the 1988 earthquake claimed the lives of 1,450 people and, despite its relatively low magnitude, again damaged more than 80,000 buildings. Railways, bridges and roads were also seriously affected.

Very few losses insured

Economic losses from the quakes of 25 April and 12 May are estimated at US$ 5.6bn (90% of these in Nepal), of which roughly US$ 210m was insured. Life insurers estimate that they have to pay out less than a million US dollars for local people, as only around 4% of the victims were insured. Sectors such as housing, education, cultural heritage and healthcare were the worst affected (Fig. 2). Most private residential buildings had no insurance cover. Only damage to newer buildings, whose construction had been financed by banks, was generally covered. Tourism is of key importance to Nepal’s economy, with over half a million visitors from abroad each year, and it is estimated that there were 20,000 visitors in the country in April at the time of the earthquake. Many world-famous monuments were badly damaged, a number of which were on the UNESCO list of world heritage sites. They included 700 historical, mostly Buddhist, structures with the typical pagodas and stupas, and it is unlikely that they can all be rebuilt. Given the importance of tourism, the Nepalese government was anxious to reopen some of the most important sites as quickly as possible (e.g. Bhaktapur Durbar Square, Hanuman Dhoka Durbar Square, Bodnath Stupa, Patan Durbar Square, the Pashupatinath Temple). In early June then, the local Ministry for Culture and Tourism declared that Nepal was again a safe travel destination. However, reconstruction work on the most important cultural sites is likely to take at least another five years.

Mountain tourism affected

The mountains are a further tourist attraction. In particular, Mount Everest, rising to an altitude of 8,848 metres, and which the earthquake pushed roughly four centimetres to the southwest, is a prime destination for many people. An avalanche of snow and ice on Pumori, a neighbouring seven-thousand metre peak, claimed a number of victims. At least 19 mountaineers and Sherpas were killed at Everest Base Camp, while others were injured. Two weeks after the quake, under pressure from international expeditions, the government initially permitted preliminary activities to reopen the traditional route through the Khumbu Icefall. (Nepal Tourism Association: “… climbing will continue, there is no reason for anyone to quit their expedition”). However, shortly afterwards, the Nepalese and Chinese authorities decided to prohibit all further expeditions. As a consequence, 2015 was the first time in 41 years that no one climbed Mount Everest.

Hold-ups in distributing billions in aid

The international community and charity organisations had promised Nepal billions in aid by the end of June. However, due to protests against the new constitution, very little government aid reached those affected. The authorities came under fire immediately after the earthquake because complicated customs procedures were stopping relief supplies getting into the country. In the absence of official assistance, people have been helping themselves as best they can. They have turned to friends and family abroad, or are trying to earn the money needed to rebuild their homes by working in Qatar or Saudi Arabia.

Need to heighten risk awareness

Prompted by the Global Earthquake Model (GEM) community initiative, supported by Munich Re, a study appeared in August 2015 on the seismic hazard and risk situation in Nepal. The findings from this study provide an important basis for making political decisions on land use, building codes, structure of the insurance industry, and catastrophe planning. With adequate risk assessment, it is possible to reduce the social and economic consequences of earthquakes. The Kathmandu Valley Earthquake Risk Management Project, also supported by Munich Re, was launched back in 1995. Its objective is to make school buildings more sturdy by giving due consideration to earthquake-resistant construction methods and effective structural reinforcing elements. A total of 300 schools have already benefited from the project, 270 of which were in the recently affected earthquake area. None of these buildings sustained significant damage, whereas 80% of the other schools were badly damaged or even destroyed. A further positive knock-on effect from the project is that earthquake-resistant construction methods have also been used in many villages for newly built housing. Nepal intends to replace all the schools that collapsed with new, reinforced buildings within the ambitious period of five years. The cost for this is likely to be in the region of US$ 400m. However, international organisations believe the schedule is unrealistic, since it would involve the construction of over 1,200 new buildings a year.

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