Nepal Case Study EQ 2015 PDF

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Seismic hazard case study: Nepal 2015 1.Describe the spatial and temporal setting of the event Where did the event take place? Where was the epicentre and focus? (depth km). Link to impacts, preparedness, mitigation. Include location maps and photos with relevant captions. 2.Describe and explain the association of the event to plate boundaries and plate movement What was the magnitude and intensity? Which plate boundaries were involved? How fast were they both moving? Does this area typically experience many earthquakes? Of what scale? Link this to earthquake preparedness or adaptation. Refer to your plate boundaries map and useful diagrams e.g. of plate movements or draw your own. 3. Assess the perception of the event, and the factors affecting those perceptions at a range of scales – eg, magnitude, frequency, population characteristics etc. Why do some earthquakes cause more deaths than others? Were people prepared? Did they expect it? When was the last earthquake? Link S&T aspect to preparedness. What was the cultural and socio-economic dimension affecting perception? 4. Explain the causes of the event Why does this continental collision zone (destructive boundary) experience earthquakes? Why was there a big one here in 2015? Why do earthquakes happen? Link to convection currents and slab pull/ridge push theory. Where was strain energy building up? Why are earthquakes inevitable based on plate motion? Why are powerful ones more likely along this boundary? 5. Explain and assess the impacts of the event – includes generic example! Explain the primary and secondary impacts. Assess them. Which were most/least significant and why? Include social, economic and environmental impacts e.g. ‘the most significant impact was the primary impact of X thousand deaths. This is chiefly a social impact; families will be permanently affected through deaths and injuries and potentially living in fear long after the event. Moreover, they will also suffer the loss of a money earner if an adult has died. If a child dies it is also a longterm economic and social loss, because the parents will not be looked after by their children in old age. As Nepal is a LIC it lacks a care system or NHS like the UK’s so this will negatively affect the parents’ quality of life in older age.’ These are far greater consequences than the lost of even several thousand buildings since these can be reconstructed and made even more earthquake resilient for the next earthquake. However, in the case of death it is final and there is no way of ‘improving’ or preparing to make this situation better for the future. Long-term psychological harm can be done which never gets repaired even with the passage of time.’ 6.Explain, assess and justify the response to the event including the factors affecting this response. What were the immediate and longer term responses? Link to: mitigation, preparedness and prevention. Explain how they worked. Did they work? Assess the effectiveness of responses? Why? Decide whether the rescue, relief, rebuilding and longer term reconstruction has been effective? Is Nepal becoming more resilient 2 years after the earthquake to help it cope when it happens again? Justify why the authorities responded as they did? If responses were limited, was this primarily about money? A lack of investment in monitoring and preparedness? Due to Nepal’s debts and lack of money for hazard management? How did people react? How did charities and foreign governments react?

Nepal Earthquake 2015

1.Describe the spatial and temporal setting of the event (Where did the event take place? Where was the epicentre and focus? (depth km). Link to impacts, preparedness, mitigation. Include location maps and photos with relevant captions.) The April 2015 Nepal earthquake occurred at 11:56 Nepal Standard Time at a depth of approximately 15 km (which is considered shallow and therefore more damaging than quakes that originate deeper in the ground), with its epicentre approximately 34 km east-southeast of Lamjung, Nepal, lasting approximately fifty seconds. The first quake measured 7.8 Mw and its epicenter was identified at a distance of 80 km to the northwest of Kathmandu, the capital of Nepal. Bharatpur was the nearest major city to the main earthquake, 53 km from the epicenter. The second earthquake was somewhat less powerful at 6.6 M. It occurred 65 km east of Kathmandu and its seismic focus lay at a depth of 10 km below the earth's surface. Over thirty-eight aftershocks of magnitude 4.5 M or greater occurred in the day following the initial earthquake, including the one of magnitude 6.8 M. The risk of a large earthquake was well known beforehand. In 2013, in an interview with seismologist Vinod Kumar Gaur, The Hindu quoted him as saying, "Calculations show that there is sufficient accumulated energy, now to produce an 8magnitude earthquake. I cannot say when. It may not happen tomorrow, but it could possibly happen sometime this century, or wait longer to produce a much larger one."

2.Describe and explain the association of the event to plate boundaries and plate movement (What was the magnitude and intensity? Which plate boundaries were involved? How fast were they both moving? Does this area typically experience many earthquakes? Of what scale? Link this to earthquake preparedness or adaptation. Refer to your plate boundaries map and useful diagrams e.g. of plate movements or draw your own) The earthquake had a magnitude of 7.8Mw or 8.1Ms and a maximum Mercalli Intensity of IX (Violent). Its epicenter was east of Gorkha District at Barpak, Gorkha, and its hypocenter was at a depth of approximately 8.2 km. It was the worst natural disaster to strike Nepal since the 1934 Nepal–Bihar earthquake. The ground motion recorded in Kathmandu valley was of low frequency which, along with its occurrence at an hour where many people in rural areas were working outdoors, decreased the loss of property and human life. According to "Did You Feel It?" responses on the USGS website, the intensity in small parts of Kathmandu was IX (Violent). In most of Kathmandu the intensity was VI, as evidenced by the numerous undamaged water towers installed on top of undamaged multi story buildings. Tremors were felt in the neighboring Indian states of Bihar, Uttar Pradesh, Assam, West Bengal, Sikkim, Jharkhand, Uttarakhand, Gujarat, in the National capital region around New Delhi.

Two tectonic plates meet beneath the Himalayas along a fault line. The India plate is moving north at around 45mm a year and pushing under the Eurasian plate. Over time that is how the Himalayas were created. The causes of Nepal earthquake 2015 was thrust fault which meant that the crushes of tectonic plates formed thrust fault where Indian plate pushed under Eurasian plate. The earthquake relieved compressional pressure between the Eurasian tectonic plate and the Indian section of the Indo-Australian Plate, which subducts (underthrusts) the Eurasian Plate. Subduction in the Himalayas occurs at an average rate of 4–5 cm annually. Such tectonic activity adds more than 1 cm to the height of the Himalayan mountains every year.

A second major earthquake occurred on 12 May 2015 at 12:50 NST with a moment magnitude of 7.3M,18 km southeast of Kodari. The epicenter was near the Chinese border between the capital of Kathmandu and Mt. Everest. It struck at the depth of 18.5 km. This earthquake occurred along the same fault as the original magnitude 7.8 earthquake of 25 April but further to the east. As such, it is considered to be an aftershock of the 25 April quake. Tremors were also felt in northern parts of India including Bihar, Uttar Pradesh, West Bengal and other North-Indian States.

3. Assess the perception of the event, and the factors affecting those perceptions at a range of scales – eg, magnitude, frequency, population characteristics etc. (Why do some earthquakes cause more deaths than others? Were people prepared? Did they expect it? When was the last earthquake? Link S&T aspect to preparedness. What was the cultural and socio-economic dimension affecting perception?) Nepal is a mulita hazard zone with steep mountain landscape; it is exposed to landslides, debris and floods, as well as earthquakes. The low level of development means that much of the local earthquake science is out of date – the current seismic hazard map is around 20 years old. Kathmandu valet has a population of 2.5 million people and a very high population density (13 000 per km3). It is also growing at 4% a year, making it one of the fastest - urbanising areas in South Asia. The earthquake on 25 April 2015 was an extreme event that people – both experts and Nepal’s inhabitants themselves – had been expecting for a long time, yet no one was adequately prepared for it. In general, cultural and economical factors affect a population’s risk exposure/vulnerability and its capacity to cope with natural disasters. In Nepal the low standard of living in general (Nepal is still one of the poorest and least developed countries in the world; more than 50 percent of its population lives below the poverty line of 1.25 US dollars per day), sustained high population growth and migration as well as the social exclusion of certain population groups, are important factors. All of this leads to a low capacity to cope with disasters and makes the people in Nepal are likely to be influenced to the negative consequences of natural events. If a similar event were to take place today the consequences would most likely be even more catastrophic than those of the earthquake on 25 April, as the Kathmandu Valley now has an estimated population of 2.5 million, the structural density of buildings is increasing massively – and is largely uncontrolled – and building

regulations, in particular those which apply to earthquake resistant building methods, are ignored. The fire brigade and civil protection authorities have neither the equipment nor the staff required to implement the necessary measures in the event of such a disaster (and are often absent in rural regions). Earthquake experts consider Kathmandu one of the most dangerous places in the world. Simulations of the potential consequences of a severe earthquake calculate a theoretical death toll of more than 100,000 in the Kathmandu Valley alone. The geological make-up of the valley floor, which consists of 500-metre-thick, unconsolidated sediments of sand and mud in places, is particularly precarious. Not only can this increase the vibration in the case of an earthquake but it can also lead to what is known as soil liquefaction, which causes buildings and entire infrastructures to sink. In the worst case this could lead to the country’s only international airport – which has proven to be absolutely crucial this time – being destroyed, meaning that it could no longer be used for disaster relief. With an annual population growth rate of 6.5 percent and one of the highest urban densities in the world, the 1.5 million people living in the Kathmandu Valley were clearly facing a serious and growing earthquake risk. And for years there were no building codes and rampant development so homes and other structures could be built without any regards to earthquakes. Poverty and pollution make the problem worse, Jackson said. That's because people don't spend time worrying about some future earthquake because they have more pressing problems. People in the Kathmandu Valley have other priorities, daily threats in terms of air quality, water quality, pollution, traffic and just poverty. But it doesn't mean that the earthquakes go away."

4. Explain the causes of the event (Why does this continental collision zone (destructive boundary) experience earthquakes? Why was there a big one here in 2015? Why do earthquakes happen? Link to convection currents and slab pull/ridge push theory. Where was strain energy building up? Why are earthquakes inevitable based on plate motion? Why are powerful ones more likely along this boundary?) The causes of Nepal earthquake 2015 was thrust fault which meant that the crushes of tectonic plates formed thrust fault where Indian plate pushed under Eurasian plate. The earthquake relieved compressional pressure between the Eurasian tectonic plate and the Indian section of the IndoAustralian Plate, which subducts (underthrusts) the Eurasian Plate. Subduction in the Himalayas occurs at an average rate of 4–5 cm annually. Such tectonic activity adds more than 1 cm to the height of the Himalayan mountains every year.

Nepal is based on a Continental – Continental converge plate boundaries. This is when two continents meet head on, neither is subducted because the continental rocks are relatively light and resist downward motion. Instead the crust tends to buckle and be pushed upward or sideways.

Volcanic activity does not occur at this margin because there is no subduction but shallow focus earthquakes can be triggered. Shallow focus earthquakes can be more dangerous and intense as the seismic waves can be felt more. The risk of a large earthquake was well known beforehand. In 2013, in an interview with seismologist Vinod Kumar Gaur, The Hindu quoted him as saying, "Calculations show that there is sufficient accumulated energy, now to produce an 8magnitude earthquake. I cannot say when. It may not happen tomorrow, but it could possibly happen sometime this century, or wait longer to produce a much larger one."...