Wednesday, April 29, 2015
The 2015 Nepal earthquake (also referred to as the Himalayan earthquake) occurred at 11:56 NST on 25 April with a moment magnitude (Mw) of 7.8 or 8.1Ms and a maximum Mercalli Intensity of IX (Violent). Its epicenter was approximately 34 km (21 mi) east-southeast of Lamjung, Nepal, and its hypocenter was at a depth of approximately 15 km (9.3 mi).
It was the most powerful disaster to strike Nepal since the 1934 Nepal–Bihar earthquake. As of 28 April 2015, more than 10,000 people were believed to have died as a result, with casualties reported in Nepal and adjoining areas of India, China, and Bangladesh. Within minutes of the earthquake, the Government of India, via the Indian Armed Forces, initiated Operation Maitri (English: Operation Amity), a massive humanitarian mission with the primary objective of conducting relief and rescue operations in Nepal. The Indian government also evacuated Indian and foreign citizens from Nepal.
The earthquake triggered an avalanche on Mount Everest, killing at least 19. The death toll surpassed that of the2014 Mount Everest avalanche, making it the most lethal day on the mountain. It triggered another huge avalanche in Langtang valley, where 250 are now missing. Centuries-old buildings were destroyed at UNESCO World Heritage sites in the Kathmandu Valley, including some at the Kathmandu Durbar Square, the Patan Durbar Square and theBhaktapur Durbar Square. Nepal's government has declared three days of mourning after the quake.
Geophysicists and other experts had warned for decades that Nepal was vulnerable to a deadly earthquake, particularly because of its geology, urbanization, and architecture.
Continued aftershocks occurred throughout Nepal, with one shock reaching a magnitude of 6.7 on 26 April at 12:54:08NST. The country is at continued risk of landslides as well.
The earthquake occurred on 25th April 2015 at 11:56am NST (06:11:26 UTC) at a depth of approximately 15 km (9.3 mi) (which is considered shallow and therefore more damaging than quakes that originate deeper in the ground), with its epicenter approximately 34 km (21 mi) east-southeast of Lamjung, Nepal, lasting approximately twenty seconds. The earthquake was initially reported as 7.5 Mw by the United States Geological Survey (USGS) before it was quickly upgraded to 7.9 Mw and finally downgraded to 7.8 Mw. The China Earthquake Networks Center (CENC) reported the earthquake's magnitude to be 8.1 Ms. The India Meteorological Department (IMD) said two powerful quakes were registered in Nepal at 06:11 UTC and 06:45 UTC. The first quake measured 7.9 Mw and its epicenter was identified at a distance of 80 km to the northwest of the capital Kathmandu. The second earthquake was somewhat less powerful at 6.6 Mw. The seismic focus lay at a depth of 10 km (6.2 mi) below the earth's surface. Bharatpur was the nearest major city to the main earthquake, 53 km (33 mi) from the epicenter. The second earthquake occurred 81 km (50 mi) northwest of Kathmandu, the capital of Nepal. Over thirty-five aftershocks of magnitude 4.5 Mw or greater occurred in the day following the initial earthquake, including the one of magnitude 6.6 Mw.
According to the USGS, the temblor was caused by a sudden thrust, or release of built-up stress, along the major fault line where the Indian Plate, carrying India, is slowly diving underneath the Eurasian Plate, carrying much of Europe and Asia. Kathmandu, situated on a block of crust approximately 120 km (75 miles) wide and 60 km (37 miles) long, reportedly shifted 3 m (10 ft) to the south in just 30 seconds.
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 [in the MFT], now to produce an 8 magnitude 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." According to Brian Tucker, founder of a nonprofit organisation devoted to reducing casualties from natural disasters, some government officials had expressed confidence that such an earthquake would not occur again. Tucker recounted a conversation he had had with a government official in the 1990s who said, "We don't have to worry about earthquakes anymore, because we already had an earthquake"; the previous earthquake to which he referred occurred in 1934.
Nepal lies towards the southern limit of the diffuse collisional boundary where the Indian Plate underthrusts the Eurasian Plate, occupying the central sector of the Himalayan arc, nearly one third of the 2,400 km (1,500 mi) long Himalayas. Geologically, the Nepal Himalayas are sub-divided into five tectonic zones from north to south, east to west and almost parallel to sub-parallel. These five distinct morpho-geotectonic zones are: (1) Terai Plain, (2) Sub Himalaya (SivalikRange), (3) Lesser Himalaya (Mahabharat Range and mid valleys), (4) Higher Himalaya, and (5) Inner Himalaya (Tibetan Tethys). Each of these zones is clearly identified by their morphological, geological, and tectonic features.
The convergence rate between the plates in central Nepal is about 45 mm (1.8 in) per year. The location, magnitude, andfocal mechanism of the earthquake suggest that it was caused by a slip along the Main Frontal Thrust.
The earthquake's effects were amplified in Kathmandu as it sits on the Kathmandu Basin, which contains up to 600 m (2,000 ft) of sedimentary rocks, representing the infilling of a lake.
Based on a study published in 2014, of the Main Frontal Thrust, on average a great earthquake occurs every 750 ± 140 and 870 ± 350 years in the east Nepal region. A study from 2015 found a 700-year delay between earthquakes in the region. The study also suggests that because of tectonic stress buildup, the earthquake from 1934 in Nepal and the 2015 quake are connected, following a historic earthquake pattern.
According to "Did You Feel It?" (DYFI?) responses on the USGS website, the intensity in Kathmandu was IX (Violent).Tremors were felt in the neighboring Indian states of Bihar, Uttar Pradesh, Assam, West Bengal, Sikkim, Uttarakhand,Odisha, Andhra Pradesh, Gujarat, in the Indian capital region around New Delhi and as far south as Karnataka. Many buildings were brought down in Bihar. Minor cracks in the walls of houses were reported in Odisha. Minor quakes were registered as far as Kochi in the southern state of Kerala. The intensity in Patna was V (Moderate). The intensity was IV (Light) in Dhaka, Bangladesh. The earthquake was also experienced across southwestern China, ranging from the Tibet Autonomous Region to Chengdu, which is 1,900 km (1,200 mi) away from the epicenter. Tremors were felt inPakistan and Bhutan.
A major aftershock of magnitude 6.7 Mw occurred on 26 April 2015 in the same region at 12:55 NST (07:09 UTC), with an epicenter located about 17 km (11 mi) south of Kodari, Nepal. The aftershock caused fresh avalanches on Mount Everest and was felt in many places in northern India including Kolkata, Siliguri, Jalpaiguri and Assam. The aftershock caused a landslide on the Koshi Highway which blocked the section of the road between Bhedetar and Mulghat.
A model of GeoGateway, based on a United States Geological Survey mechanism of a near-horizontal fault as well as location of aftershocks showed that the fault was an 11° dip striking at 295°, 50 km (31 mi) wide, 150 km (93 mi) long, and had a dip slip of 3 m (9.8 ft). The USGS says the aftershock on Sunday registered at a shallow depth of 10 km (6.2 mi).
Assuming that this earthquake is the largest event in this seismic episode, Nepal can expect more than 30 aftershocks greater than magnitude 5 over the next month.
UNICEF announced that close to 1 million children were "severely affected" by the disaster. On 27 April, The Himalayan Times reported that as many as 20,000 foreign nationals may have been visiting Nepal at the time of the earthquake. As reports come in from isolated villages, it is possible that total deaths may reach or exceed the more than 10,000 killed in the 1934 earthquake. Hundreds of people are still considered missing and more than 450,000 are displaced.
As of 4:14 p.m. 27 April in India, Home Minister Rajnath Singh confirmed that 56 people died in the state ofBihar, 12 in Uttar Pradesh, 3 in West Bengal and 1 in Rajasthan.
The death toll in Nepal has now crossed 5,000. The Nepal Prime Minister, Sushil Koirala has said that the number could reach 10,000.
Avalanches on Mount Everest
Main article: 2015 Mount Everest avalanches
This earthquake caused many avalanches on Mount Everest. At least 19 climbers, including Google executive Dan Fredinburg, are dead, with dozens injured or missing.
Avalanche in the Langtang valley
In the Langtang valley, around 250 people have been reported missing after a huge avalanche that resulted in the village of Langtang itself being wiped out.
The Tribhuvan International Airport serving Kathmandu was closed immediately after the quake, but was re-opened later in the day for relief operations, with commercial flights planned to resume on April 26. It has since shut down operations sporadically due to aftershocks, and many workers are not at their posts, either from becoming earthquake casualties or because they are dealing with its aftereffects.
Buildings in Kathmandu Durbar Square, a UNESCO World Heritage Site, collapsed, as did the Dharahara tower, built in 1832; the collapse of the latter structure killed at least 180 people, Manakamana Temple in Gorkha was also destroyed. The northern side of Janaki Mandir has been reported to be damaged. Several temples, includingKasthamandap, Panchtale temple, the nine-storey Basantapur Durbar, the Dasa Avtar temple and two dewals located behind the Shiva Parvati temple were demolished by the quake. Few other monuments, including the Kumari Temple and the Taleju Bhawani Temple, among others, have partially collapsed.
The top of the Jay Bageshwori Temple in Gaushala and some parts of the Pashupatinath Temple, Swyambhunath, BoudhanathStupa, Ratna Mandir, inside Rani Pokhari, and Durbar High School have been destroyed. Telephone service in Kathmandu has been sporadic since the quake, as has electricity.
In Patan, the Char Narayan Mandir, the statue of Yog Narendra Malla, a pati inside Patan Durbar Square, the Taleju Temple, the Hari Shanker, Uma Maheshwor Temple and the Machhindranath Temple in Bungmati were destroyed. In Tripureshwor, the Kal Mochan Ghat, a temple inspired by Mughal architecture, was completely destroyed and the nearby Tripura Sundari also suffered significant damage. In Bhaktapur, several monuments, including the Fasi Deva temple, the Chardham temple and the 17th century Vatsala Durga Temple, were fully or partially destroyed.
Outside the Valley, the Manakamana Temple in Gorkha, the Gorkha Durbar, the Palanchowk Bhagwati, in Kavrepalanchowk District, the Rani Mahal in Palpa District, the Janaki Mandir in Janakpur, the Churiyamai in Makwanpur District, the Dolakha Bhimsensthan inDolakha District, and the Nuwakot Durbar were partially destroyed.
Historian Prushottam Lochan Shrestha stated, "We have lost most of the monuments that had been designated as World Heritage Sites in Kathmandu, Bhaktapur and Lalitpur District, Nepal. They cannot be restored to their original states."
Coverage on social media"This is a very catastrophic event in a very poor nation. The cost of reconstruction over the next few years will be massive. Rebuilding costs could easily exceed USD$5 billion, which would be about 20 percent of Nepal's gross domestic product. Massive international disaster relief and rescue efforts will be needed urgently, as well as large-scale international financial and technical assistance for long-term reconstruction of the economy." said Rajiv Biswas, chief Asia-Pacific economist at Colorado-based consultancy services IHS Inc.Nepal, with a total GDP of $19.921 billion (according to a 2012 estimate), is one of Asia's poorest countries, and has little ability to fund a major reconstruction effort on its own. Even before the quake, the Asian Development Bank estimated that it would need to spend about four times more than it currently does annually on infrastructure through 2020 to attract investment. The U.S. Geological Survey initially estimated economic losses from the temblor at 9 percent to 50 percent of gross domestic product, with a best guess of 35 percent. "It’s too hard for now to tell the extent of the damage and the effect on Nepal’s GDP", according to Hun Kim, an Asian Development Bank (ADB) official. The ADB said on the 28th that it would provide a USD$3 million grant to Nepal for immediate relief efforts, and up to USD$200 million for the first phase of rehabilitation.
The earthquake has received extensive coverage on social networking sites such as Facebook and Twitter. Close to 5 million tweets related to Nepal was published during the first three days following the disaster.. Official Nepal government social media profiles also have been used by the Nepal Police, the Office of the Prime Minister of Nepal Prime Minister's Disaster Relief Fund and the National Emergency Operation Centre.. A group of popular Nepalese accounts on social media, such as @KanakManiDixit @Ekendra and @salokya, have been constantly providing rescue and relief information to the world. The hashtag #NepalEarthquake is in popular use, and on reddit a subreddit titled /r/NepalEarthquake has been created.
International humanitarian response
Main articles: Humanitarian response to the 2015 Nepal earthquake and Operation Maitri
Within 15 minutes of the earthquake on April 25, 2015, the Government of India, via the Indian Armed Forces, initiated Operation Maitri (English: Operation Amity), with the primary objective of conducting relief and rescue operations in Nepal. On Sunday April 26, 2015, International aid agencies and governments mobilized to respond to the earthquake in Nepal, saying they faced challenges in getting assistance to the country and distributing it amid the widespread devastation there.The global response is being coordinated by the Nepalese government through its National Emergency Operation Center.[