NEPAL EARTHQUAKE

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April 2015 Nepal earthquake

1. More than 4,300 people die after amagnitude-7.8 earthquake strikes Nepal.
2. Nepal's Prime Minister, Sushil Koirala, has said that the number could reach 10,000

The 2015 Nepal earthquake (the Himalayan earthquake) which is believed to have killed more than 6,100 people as of 29 April 2015, 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. Some casualties have also been reported in the adjoining areas of India, China, and Bangladesh. India responded with Operation Maitri for rescue and relief in Nepal by its armed forces and also evacuated Indian and foreign citizens from Nepal.

The earthquake triggered an avalanche on Mount Everest, killing at least 19,making it the deadliest day on the mountain in history. 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 PatanDurbar Square and the Bhaktapur 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 12:54:08 NST. The country is at continued risk of landslides as well.

The earthquake occurred on 25 April 2015 at 11:56 a.m. 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 epicenterapproximately 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. India Meteorological Department (IMD) said two powerful quakes were registered in Nepal at 06:11 UTC and 06:45 UTC. The w 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.

 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 (Sivalik Range), (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, and focal 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) ofsedimentary 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[35] 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 in Pakistan 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).

 Nepal's Prime Minister, Sushil Koirala, has said that the number could reach 10,000.

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 of Bihar, 12 in Uttar Pradesh, 3 in West Bengal and 1 in Rajasthan.

first quake measured 7.9 M

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.