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105-745: Patan Durbar Square was heavily damaged by the earthquake in April 2015 . Former International Artists in Residence include Nancy Condon, Jessica Melville-Brown, and Joy Lynn Davis. The current chairman of the Board of Directors is Kedar Bahadur Adhikari, from the Ministry of Culture, Tourism and Civil Aviation , Singh Durbar , Kathmandu. The entrance fees are 1000 Nepalese rupees for foreign visitors, 250 for SAARC visitors, 30 for Nepali visitors, and 15 for Nepalese students (with identification). The Patan Museum's mission

210-724: A United States Geological Survey mechanism of a near-horizontal fault as well as the location of aftershocks showed that the fault had an 11° dip towards the north, striking at 295°, was 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 registered at a shallow depth of 10 km (6.2 mi). As of 24 May 2016, 459 aftershocks had occurred with different epicenters and magnitudes equal to or above 4 M w (out of which 51 aftershocks are equal to or above 5 M w and 5 aftershocks above 6 M w ) and more than 20,000 aftershocks less than 4 M w . A second major earthquake occurred on 12 May 2015 at 12:50 NST with

315-522: A moment magnitude (M w ) of 7.3. The epicenter was near the Chinese border between the capital of Kathmandu and Mount Everest. More than 200 people were killed and over 2,500 were injured by this aftershock, and many were left homeless. The earthquake occurred on 25 April 2015 at 11:56 am NST (06:11:25 UTC) at a depth of approximately 8.2 km (5.1 mi) (which is considered shallow and therefore more damaging than quakes that originate deeper in

420-463: A moment magnitude (M w ) of 7.3M w 18 km (11 mi) southeast of Kodari . The epicenter was near the Chinese border between the capital city of Kathmandu and Mount Everest . It struck at a depth of 18.5 km (11.5 miles). 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 an aftershock of

525-461: A certain rate. Charles F. Richter then worked out how to adjust for epicentral distance (and some other factors) so that the logarithm of the amplitude of the seismograph trace could be used as a measure of "magnitude" that was internally consistent and corresponded roughly with estimates of an earthquake's energy. He established a reference point and the ten-fold (exponential) scaling of each degree of magnitude, and in 1935 published what he called

630-581: A collapsed wall while a teacher died of a heart attack during the earthquake. This earthquake caused avalanches on Mount Everest . At least 19 died, with at least 120 others injured or missing. In the Langtang valley located in Langtang National Park , 329 people were reported missing after an avalanche hit the village of Ghodatabela and the village of Langtang . The avalanche was estimated to have been two to three kilometres wide. Ghodatabela

735-496: A constant term ( W 0 / M o  = 5 × 10 ) in Eq. (A) and estimated M s and denoted as M w (dyn.cm). The energy Eq. (A) is derived by substituting m  = 2.5 + 0.63 M in the energy equation Log E  = 5.8 + 2.4 m (Richter 1958), where m is the Gutenberg unified magnitude and M is a least squares approximation to the magnitude determined from surface wave magnitudes. After replacing

840-470: A conversation he 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 . In fact, the 600-km-long Central Himalayan Gap hadn't ruptured since 1505 . Nepal lies towards the southern limit of the diffuse collisional boundary where the Indian plate underthrusts

945-485: A double couple, but not from a single couple. This was confirmed as better and more plentiful data coming from the World-Wide Standard Seismograph Network (WWSSN) permitted closer analysis of seismic waves. Notably, in 1966 Keiiti Aki showed that the seismic moment of the 1964 Niigata earthquake as calculated from the seismic waves on the basis of a double couple was in reasonable agreement with

1050-513: A fast and cost effective manner. Digital mappers, through the Kathmandu Living Labs , were already charting the densely populated Kathmandu Valley, and then focused on earthquake relief. "They were doing an inventory in the poorer communities where they didn't have a very good sense of the quality of buildings," says Cowan, whose students helped add Kathmandu's buildings and roads to OpenStreetMap. First responders, from Nepalese citizens to

1155-418: A general solution in 1964 by Burridge and Knopoff, which established the relationship between double couples and the theory of elastic rebound, and provided the basis for relating an earthquake's physical features to seismic moment. Seismic moment – symbol M 0   – is a measure of the fault slip and area involved in the earthquake. Its value is the torque of each of the two force couples that form

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1260-602: A government survey, malnutrition in children has worsened considerably some 3 months after the quake, with the most undernourished being Tamang and Chepang peoples. Before the quake, 41 percent of children under five were stunted, 29 percent were underweight and 11 percent were emaciated, according to the World Food Programme. Though a feared mass cholera outbreak failed to materialize (there were sporadic reports), other outbreaks were reported. At least 13 people died of scrub typhus while 240 people were taken ill since

1365-458: A long drawn out chain of events , in that one disaster feeds into another for years or even decades on end. The aftereffects of the earthquake had subsequent effects on a myriad of things: human trafficking , labour cost and availability, rental and property cost burdens, urbanization , private and public debt burdens, mental health, politics, tourism , disease, and damage to the healthcare system. A survey some 30 months later found only 12% of

1470-471: A maximum Mercalli Intensity of X ( Extreme ). Its epicenter was east of Gorkha District at Barpak, Gorkha, roughly 85 km (53 mi) northwest of central Kathmandu , and its hypocenter was at a depth of approximately 8.2 km (5.1 mi). It was the worst natural disaster to strike Nepal since the 1934 Nepal–India earthquake . The ground motion recorded in Kathmandu, the capital of Nepal,

1575-425: A nine-storey 61.88-metre (203.0 ft) tall tower, was destroyed. It was a part of the architecture of Kathmandu recognized by UNESCO. Continued aftershocks occurred throughout Nepal at intervals of 15–20 minutes, with one shock reaching a magnitude of 6.7 on 26 April at 12:54:08 NST . The country also had a continued risk of landslides. A major aftershock occurred on 12 May 2015 at 12:50 NST with

1680-402: A portion Δ W {\displaystyle \Delta W} of this stored energy is transformed into The potential energy drop caused by an earthquake is related approximately to its seismic moment by where σ ¯ {\displaystyle {\overline {\sigma }}} is the average of the absolute shear stresses on the fault before and after

1785-530: A report by the Inter-party Women's Alliance (IPWA). The report also found that violence and rapes against women and minors have increased after the earthquake. Additionally, the earthquake has significantly affected certain groups of people. Tibeto-Burman peoples were hardest hit as they tend to inhabit the higher slopes of mountains as opposed to the central valleys and are less educated and connected. All of these factors make them harder to access. According to

1890-449: A single couple model. In principle these models could be distinguished by differences in the radiation patterns of their S-waves , but the quality of the observational data was inadequate for that. The debate ended when Maruyama (1963), Haskell (1964), and Burridge and Knopoff (1964) showed that if earthquake ruptures are modeled as dislocations the pattern of seismic radiation can always be matched with an equivalent pattern derived from

1995-439: A three-decade-long controversy over the best way to model the seismic source: as a single couple, or a double couple. While Japanese seismologists favored the double couple, most seismologists favored the single couple. Although the single couple model had some shortcomings, it seemed more intuitive, and there was a belief – mistaken, as it turned out – that the elastic rebound theory for explaining why earthquakes happen required

2100-454: A week after the earthquake. As of 1 May international aid agencies like Médecins Sans Frontières and the Red Cross were able to start medically evacuating the critically wounded by helicopter from outlying areas, initially cut-off from the capital city, Kathmandu, and treating others in mobile and makeshift facilities. There was concern about epidemics due to the shortage of clean water,

2205-439: Is "the interpretation of Sacred Art , Culture and Iconography of Hinduism and Buddhism through preservation and exhibition." The museum's exhibits cover a long span of Nepal's cultural history. It has over 1,100 artifacts, about 200 of which are on permanent display. Most of the objects are cast bronzes (mostly sculptures of Hindu and Buddhist deities) and gilt copper repoussé work , traditional crafts for which Patan

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2310-403: Is a measure of an earthquake 's magnitude ("size" or strength) based on its seismic moment . M w   was defined in a 1979 paper by Thomas C. Hanks and Hiroo Kanamori . Similar to the local magnitude/Richter scale (M L  ) defined by Charles Francis Richter in 1935, it uses a logarithmic scale ; small earthquakes have approximately the same magnitudes on both scales. Despite

2415-448: Is a measure of the work (more precisely, the torque ) that results in inelastic (permanent) displacement or distortion of the Earth's crust. It is related to the total energy released by an earthquake. However, the power or potential destructiveness of an earthquake depends (among other factors) on how much of the total energy is converted into seismic waves. This is typically 10% or less of

2520-429: Is approximately related to seismic moment by where η R = E s / ( E s + E f ) {\displaystyle \eta _{R}=E_{s}/(E_{s}+E_{f})} is radiated efficiency and Δ σ s {\displaystyle \Delta \sigma _{s}} is the static stress drop, i.e., the difference between shear stresses on

2625-485: Is challenging as the source events cannot be observed directly, and it took many years to develop the mathematics for understanding what the seismic waves from an earthquake can tell about the source event. An early step was to determine how different systems of forces might generate seismic waves equivalent to those observed from earthquakes. The simplest force system is a single force acting on an object. If it has sufficient strength to overcome any resistance it will cause

2730-612: Is clearly identified by its 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) of sedimentary rocks , representing

2835-501: Is complete and ignores fracture energy), (where E is in Joules and M 0   is in N ⋅ {\displaystyle \cdot } m), Kanamori approximated M w   by The formula above made it much easier to estimate the energy-based magnitude M w  , but it changed the fundamental nature of the scale into a moment magnitude scale. USGS seismologist Thomas C. Hanks noted that Kanamori's M w   scale

2940-511: Is famous. [REDACTED] Media related to Patan Museum at Wikimedia Commons April 2015 Nepal earthquake The April 2015 Nepal earthquake (also known as the Gorkha earthquake ) killed 8,962 people and injured 21,952 across the Nepal, India, China and Bangladesh. It occurred at 11:56 Nepal Standard Time on Saturday 25 April 2015, with a magnitude of 7.8 M w or 8.1 M s and

3045-426: Is only valid for (≤ 7.0). Seismic moment is not a direct measure of energy changes during an earthquake. The relations between seismic moment and the energies involved in an earthquake depend on parameters that have large uncertainties and that may vary between earthquakes. Potential energy is stored in the crust in the form of elastic energy due to built-up stress and gravitational energy . During an earthquake,

3150-546: Is sufficient accumulated energy [in the Main Frontal Thrust ], 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 organization devoted to reducing casualties from natural disasters, some government officials had expressed confidence that such an earthquake would not occur again. Tucker recounted

3255-463: Is technically difficult since it involves the integration of wave energy over the entire frequency band. To simplify this calculation, he noted that the lowest frequency parts of the spectrum can often be used to estimate the rest of the spectrum. The lowest frequency asymptote of a seismic spectrum is characterized by the seismic moment , M 0  . Using an approximate relation between radiated energy and seismic moment (which assumes stress drop

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3360-620: Is the same for all earthquakes, one can consider M w   as a measure of the energy E s radiated by earthquakes. Under these assumptions, the following formula, obtained by solving for M 0   the equation defining M w  , allows one to assess the ratio E 1 / E 2 {\displaystyle E_{1}/E_{2}} of energy release (potential or radiated) between two earthquakes of different moment magnitudes, m 1 {\displaystyle m_{1}} and m 2 {\displaystyle m_{2}} : As with

3465-420: Is thus poorly known. It could vary highly from one earthquake to another. Two earthquakes with identical M 0 {\displaystyle M_{0}} but different σ ¯ {\displaystyle {\overline {\sigma }}} would have released different Δ W {\displaystyle \Delta W} . The radiated energy caused by an earthquake

3570-558: The Dharahara tower, built in 1832; the collapse of the latter structure killed at least 180 people, Manakamana Temple in Gorkha, previously damaged in an earlier quake, tilted several inches further. The northern side of Janaki Mandir in Janakpur was reported to have been damaged. Several temples, including Kasthamandap , Panchtale temple, the top levels of the nine-story Basantapur Durbar,

3675-698: 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 subdivided 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 ( Shivalik Range ); (3) Lesser Himalaya (Mahabharat Range and mid valleys); (4) Higher Himalaya; and (5) Inner Himalaya (Tibetan Tethys). Each of these zones

3780-439: The Eurasian plate , carrying much of Europe and Asia. Kathmandu, situated on a block of crust approximately 120 km (74 miles) wide and 60 km (37 miles) long, rapidly shifted 3 m (10 ft) to the south in a matter of 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

3885-547: The Nepalese Army were sent to the stricken areas in the aftermath of the earthquake under Operation Sankat Mochan , with volunteers mobilized from other parts of the country. Rainfall and aftershocks were factors complicating the rescue efforts, with potential secondary effects like additional landslides and further building collapses being concerns. Impassable roads and damaged communications infrastructure posed substantial challenges to rescue efforts. Survivors were found up to

3990-519: 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 series of aftershocks began immediately after the mainshock, at intervals of 15–30 minutes, with one aftershock reaching 6.6M w within 34 minutes of the initial quake. A major aftershock of magnitude 6.9 M w occurred on 26 April 2015 in

4095-489: The "magnitude scale", now called the local magnitude scale , labeled M L  . (This scale is also known as the Richter scale , but news media sometimes use that term indiscriminately to refer to other similar scales.) The local magnitude scale was developed on the basis of shallow (~15 km (9 mi) deep), moderate-sized earthquakes at a distance of approximately 100 to 600 km (62 to 373 mi), conditions where

4200-621: The 1970s, introducing a separate magnitude associated to radiated energy was warranted. Choy and Boatwright defined in 1995 the energy magnitude where E s {\displaystyle E_{\mathrm {s} }} is in J (N·m). Assuming the values of σ̄/μ are the same for all earthquakes, one can consider M w   as a measure of the potential energy change Δ W caused by earthquakes. Similarly, if one assumes η R Δ σ s / 2 μ {\displaystyle \eta _{R}\Delta \sigma _{s}/2\mu }

4305-556: The 25 April quake. Tremors were also felt in northern parts of India including Bihar , Uttar Pradesh , West Bengal and other North-Indian States. At least 153 people died in Nepal as a result of the aftershock and about 2,500 were injured. 62 others died in India, two in Bangladesh, and one in China. Disastrous events in very poor and politically paralyzed nations such as Nepal often become

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4410-770: The Char Narayan Mandir, the statue of Yog Narendra Malla, a pati inside Patan Durbar Square, the Taleju Temple, the Hari Shankar, Uma Maheshwar Temple and the Machhindranath Temple in Bungamati were destroyed. In Tripureshwar, 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

4515-768: The Dasa Avtar temple and two shrines located behind the Shiva Parvati temple were demolished by the quake. Some other monuments including the Taleju Bhawani Temple partially collapsed. The top of the Jaya Bageshwari Temple in Gaushala and some parts of the Pashupatinath Temple , Swyambhunath , Boudhanath Stupa, Ratna Mandir , inside Rani Pokhari, and Durbar High School have been destroyed. In Patan,

4620-549: The Kathmandu 2015 earthquake had been derived and the intensities of shaking had been mapped, a line source model for losses could be constructed with energy being radiated along the entire rupture. The fatalities estimated in this way by QLARM agree with those reported in the end. The figure shows reports of fatalities as a function of time. News reports significantly underestimated the actual numbers of fatalities for several days. The Himalayan Times reported that as many as 20,000 foreign nationals may have been visiting Nepal at

4725-609: The National Capital Region around New Delhi and as far south as Karnataka . Damage was extensive in northern Bihar and minor damage was also reported from parts of Odisha. Shaking was felt in high-rise buildings 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 southwest China , ranging from

4830-1297: The Phasi 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 Palanchok Bhagwati, in Kabhrepalanchok District , the Rani Mahal in Palpa District , the Churiyamai in Makwanpur District , the Dolakha Bhimsensthan in Dolakha District , and the Nuwakot Durbar suffered varying degrees of damage. Historian Prushottam Lochan Shrestha stated, "We have lost most of

4935-575: The Red Cross, the Nepal army and the United Nations used this data. The Nepal earthquake crisis mapping utilized experience gained and lessons learned about planning emergency aid work from earthquakes in Haiti and Indonesia. Moment magnitude scale The moment magnitude scale ( MMS ; denoted explicitly with M or M w   or Mwg , and generally implied with use of a single M for magnitude )

5040-452: The Richter scale, an increase of one step on the logarithmic scale of moment magnitude corresponds to a 10 ≈ 32 times increase in the amount of energy released, and an increase of two steps corresponds to a 10 = 1000 times increase in energy. Thus, an earthquake of M w   of 7.0 contains 1000 times as much energy as one of 5.0 and about 32 times that of 6.0. To make the significance of

5145-609: The West China region through the 2020s. According to the USGS website, the maximum intensity was VIII ( Severe ), however certain reports state an intensity of X ( Extreme ) or higher. In most of Kathmandu the intensity was VIII-IX, 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 , Odisha , Sikkim , Jharkhand , Uttarakhand , Gujarat , in

5250-436: The airport opened all boarding-lounge exit doors onto the tarmac, allowing people who were waiting post security and immigration to flee to the open spaces of the runway tarmac. Many remained outside as planes were delayed and the airport swelled to capacity. The airport facilities suffered damage and there was no running water or operating toilets in the airport lounges. Few airport workers were at their posts; most were killed in

5355-409: The chaos that resulted from the aftermath of the earthquake. The most affected were women from poor communities who lost their homes. In response to the unsafe conditions of the temporary campsites, international organizations implemented Safety Committees which were provided cash grants for necessities like additional toilets and bathrooms. Single women had very little access to relief, according to

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5460-470: The country, with entire villages flattened, especially those near the epicenter. The Tribhuvan International Airport serving Kathmandu was closed immediately after the earthquake, but was re-opened later in the day for relief operations and, later, for some commercial flights. It subsequently shut down operations sporadically due to aftershocks, and on 3 May was closed temporarily to the largest planes for fear of runway damage. During strong aftershocks,

5565-939: The country. 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 , the Bhaktapur Durbar Square , the Changu Narayan Temple, the Boudhanath stupa , and the Swayambhunath stupa. Geophysicists and other experts had warned for decades that Nepal was vulnerable to a deadly earthquake, particularly because of its geology, urbanization, and architecture. Dharahara , also called Bhimsen Tower,

5670-421: 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 US$ 3 million grant to Nepal for immediate relief efforts, and up to US$ 200 million for the first phase of rehabilitation. Rajiv Biswas, an economist at a Colorado -based consultancy, said that rebuilding the economy will need international effort over

5775-569: The deficiencies of the M L   scale, but all are subject to saturation. A particular problem was that the M s   scale (which in the 1970s was the preferred magnitude scale) saturates around M s  8.0 and therefore underestimates the energy release of "great" earthquakes such as the 1960 Chilean and 1964 Alaskan earthquakes. These had M s   magnitudes of 8.5 and 8.4 respectively but were notably more powerful than other M 8 earthquakes; their moment magnitudes were closer to 9.6 and 9.3, respectively. The study of earthquakes

5880-444: The difference, news media often use the term "Richter scale" when referring to the moment magnitude scale. Moment magnitude (M w  ) is considered the authoritative magnitude scale for ranking earthquakes by size. It is more directly related to the energy of an earthquake than other scales, and does not saturate – that is, it does not underestimate magnitudes as other scales do in certain conditions. It has become

5985-523: The disease was first diagnosed in the country in August 2015 until September 2016. The mental and emotional impact of an earthquake is the other invisible disaster. Medical Doctors from India, Ramachandra Kamath, Edmond Fernandes and Prakash Narayan stated that elderly care in disaster was more important than women and child focused one for Nepal earthquake and absence of military support for medical aid providers impacted relief work. About 90% of soldiers from

6090-468: The earth's surface. Over 38 aftershocks of magnitude 4.5 M w   or greater occurred in the day following the initial earthquake, including one of 6.8 M w  . According to the USGS, the earthquake was caused by a sudden thrust, a short sharp thrust that caught many unsuspected and dies to this thrust only, along the major fault line where the Indian plate , carrying India, is slowly diving underneath

6195-428: The earthquake (e.g., equation 3 of Venkataraman & Kanamori 2004 ) and μ {\displaystyle \mu } is the average of the shear moduli of the rocks that constitute the fault. Currently, there is no technology to measure absolute stresses at all depths of interest, nor method to estimate it accurately, and σ ¯ {\displaystyle {\overline {\sigma }}}

6300-420: The earthquake or had to deal with its aftereffects. Flights resumed from Pokhara, to the west of the epicentre, on 27 April. Several of the churches in the Kathmandu valley were destroyed. As Saturday is the principal day of Christian worship in Nepal, 500 people were reported to have died in the collapses. Several temples on Kathmandu Durbar Square , a UNESCO World Heritage Site , collapsed, as did

6405-399: The earthquake's equivalent double-couple. (More precisely, it is the scalar magnitude of the second-order moment tensor that describes the force components of the double-couple. ) Seismic moment is measured in units of Newton meters (N·m) or Joules , or (in the older CGS system) dyne-centimeters (dyn-cm). The first calculation of an earthquake's seismic moment from its seismic waves

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6510-409: The energy released, and the stress drop (essentially how much of the potential energy was released). In particular, he derived an equation that relates an earthquake's seismic moment to its physical parameters: with μ being the rigidity (or resistance to moving) of a fault with a surface area of S over an average dislocation (distance) of ū . (Modern formulations replace ūS with

6615-402: The epicentre of the earthquake was in a rural setting, so the worst hit districts had low population densities and most of the population was outside when the earthquake hit. Had the earthquake occurred at night or during the working week, when many more people were inside vulnerable buildings, the death toll would have likely been much closer to the modelled estimate. After the rupture area of

6720-482: The equivalent D̄A , known as the "geometric moment" or "potency". ) By this equation the moment determined from the double couple of the seismic waves can be related to the moment calculated from knowledge of the surface area of fault slippage and the amount of slip. In the case of the Niigata earthquake the dislocation estimated from the seismic moment reasonably approximated the observed dislocation. Seismic moment

6825-412: The expected numbers of fatalities due to a hypothetical scenario earthquake near Kathmandu for M8.1 was published. The fatalities at that time were estimated between 21,000 and 42,000. The M7.8 earthquake of 25 April 2015 killed about 8,800 people because it occurred on a Saturday and so many buildings that collapsed, such as schools and municipal buildings, were empty, reducing the death toll. In addition,

6930-456: The fact that they only provided a comparison of the amplitude of waves produced at a standard distance and frequency band; it was difficult to relate these magnitudes to a physical property of the earthquake. Gutenberg and Richter suggested that radiated energy E s could be estimated as (in Joules). Unfortunately, the duration of many very large earthquakes was longer than 20 seconds, the period of

7035-1161: The fault before and after the earthquake (e.g., from equation 1 of Venkataraman & Kanamori 2004 ). These two quantities are far from being constants. For instance, η R {\displaystyle \eta _{R}} depends on rupture speed; it is close to 1 for regular earthquakes but much smaller for slower earthquakes such as tsunami earthquakes and slow earthquakes . Two earthquakes with identical M 0 {\displaystyle M_{0}} but different η R {\displaystyle \eta _{R}} or Δ σ s {\displaystyle \Delta \sigma _{s}} would have radiated different E s {\displaystyle E_{\mathrm {s} }} . Because E s {\displaystyle E_{\mathrm {s} }} and M 0 {\displaystyle M_{0}} are fundamentally independent properties of an earthquake source, and since E s {\displaystyle E_{\mathrm {s} }} can now be computed more directly and robustly than in

7140-681: The ground and collaborated with international crisis mapping and humanitarian organizations. Public volunteers from around the world participated in crowdmapping and added details into online maps. Information was mapped from data input from social media, satellite pictures and drones of passable roads, collapsed houses, stranded, shelterless and starving people, who needed help, and from messages and contact details of people willing to help. On-site volunteers verified these mapping details wherever they could to reduce errors. The technologies used by Kathmandu Living Labs were built on top of existing open source solutions which allowed them to work in

7245-663: The ground), with its epicentre approximately 34 km (21 mi) southeast of Lamjung , Nepal , lasting approximately 50 seconds. The earthquake was initially reported as 7.5 M w   by the United States Geological Survey (USGS) before it was quickly upgraded to 7.8 M w  . The China Earthquake Networks Center (CENC) reported the earthquake's magnitude to be 8.1 M s  . 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 7.8 M w   and its epicenter

7350-464: The houses in the three counties collapsed. Four people were killed and 18 districts were affected by the earthquake in Bangladesh. A six-story building partially collapsed and two garment factories tilted in Dhaka . A 22-year-old man died when trying to flee the Dhaka Medical College in a panic. In Tangail , a woman died trying to escape a building. Another woman was crushed to death by

7455-560: 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 1934 earthquake and the 2015 quake are connected, following a historic earthquake pattern. A 2016 study on historical great (M ≥ 8) earthquake pairs and cycles found that associated great earthquakes are likely to occur in

7560-447: The interactions of forces) this model is called a couple , also simple couple or single couple . If a second couple of equal and opposite magnitude is applied their torques cancel; this is called a double couple . A double couple can be viewed as "equivalent to a pressure and tension acting simultaneously at right angles". The single couple and double couple models are important in seismology because each can be used to derive how

7665-504: The local magnitude and the surface wave magnitude. Thus, a magnitude zero microearthquake has a seismic moment of approximately 1.1 × 10  N⋅m , while the Great Chilean earthquake of 1960, with an estimated moment magnitude of 9.4–9.6, had a seismic moment between 1.4 × 10  N⋅m and 2.8 × 10  N⋅m . Seismic moment magnitude ( M wg or Das Magnitude Scale ) and moment magnitude ( M w ) scales To understand

7770-416: The magnitude range 5.0 ≤  M s  ≤ 7.5 is not reliable due to the inconsistency of defined magnitude range (moderate to large earthquakes defined as M s  ≤ 7.0 and M s  = 7–7.5) and scarce data in lower magnitude range (≤ 7.0) which rarely represents the global seismicity (e.g., see Figs. 1A, B, 4 and Table 2 of Percaru and Berckhemer 1978). Furthermore, Equation (1) of Percaru and Berckhemer 1978)

7875-710: The magnitude scales based on M o detailed background of M wg and M w scales is given below. M w scale Hiroo Kanamori defined a magnitude scale (Log W 0  = 1.5 M w  + 11.8, where W 0 is the minimum strain energy) for great earthquakes using Gutenberg Richter Eq. (1). Log Es = 1.5 Ms + 11.8                                                                                     (A) Hiroo Kanamori used W 0 in place of E s (dyn.cm) and consider

7980-427: The magnitude value plausible, the seismic energy released during the earthquake is sometimes compared to the effect of the conventional chemical explosive TNT . The seismic energy E S {\displaystyle E_{\mathrm {S} }} results from the above-mentioned formula according to Gutenberg and Richter to or converted into Hiroshima bombs: For comparison of seismic energy (in joules) with

8085-596: The makeshift nature of living conditions and the lack of toilets. Emergency workers were able to identify four men who had been trapped in rubble, and rescue them, using advanced heartbeat detection. The four men were trapped in up to ten feet of rubble in the village of Chautara, north of Kathmandu. An international team of rescuers from several countries using FINDER devices found two sets of men under two different collapsed buildings. Volunteers used crisis mapping to help plan emergency aid work. Local organization Kathmandu Living Labs helped coordinate local knowledge on

8190-410: The moment magnitude scale is M w  , with the subscript "w" meaning mechanical work accomplished. The moment magnitude M w   is a dimensionless value defined by Hiroo Kanamori as where M 0   is the seismic moment in dyne ⋅cm (10  N⋅m). The constant values in the equation are chosen to achieve consistency with the magnitude values produced by earlier scales, such as

8295-454: 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." The northeastern parts of India also received major damage. Heavy shocks were felt in the states of Uttrakhand, Uttar Pradesh, West Bengal and others. Huge damage was caused to the property and the lives of the people. Concern

8400-400: The next few years as it could "easily exceed" US$ 5 billion. More recent studies estimate the damage from the earthquake to be closer to US$ 10 billion (which would be around 50% of Nepals GDP at the time). It was reported that the survivors were preyed upon by human traffickers involved in the supply of girls and women to the brothels of South Asia. These traffickers took advantage of

8505-463: The object to move ("translate"). A pair of forces, acting on the same "line of action" but in opposite directions, will cancel; if they cancel (balance) exactly there will be no net translation, though the object will experience stress, either tension or compression. If the pair of forces are offset, acting along parallel but separate lines of action, the object experiences a rotational force, or torque . In mechanics (the branch of physics concerned with

8610-691: The quake contributed to such events is often unknown and unresearched, but it is certainly possible. The earthquake killed at least 8,857 people in Nepal and injured nearly three times as many. The rural death toll may have been minimized by the fact that most villagers were outdoors working when the quake hit. As of 15 May, 6,271 people, including 1,700 from the 12 May aftershock, were still receiving treatment for their injuries. Nearly 3.5 million people were left homeless, causing around 2.6 million internal displacements . The example of this earthquake shows that loss calculations for hypothetical likely future earthquakes can be reasonably reliable. In 2005,

8715-467: 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 to 2020 to attract investment. The U.S. Geological Survey initially estimated economic losses from the tremor at 9 per cent to 50 per cent of gross domestic product, with a best guess of 35 per cent. "It's too hard for now to tell the extent of

8820-581: The ratio of seismic Energy ( E ) and Seismic Moment ( M o ), i.e., E / M o  = 5 × 10 , into the Gutenberg–Richter energy magnitude Eq. (A), Hanks and Kanamori provided Eq. (B): Log M0 = 1.5 Ms + 16.1                                                                                   (B) Note that Eq. (B)

8925-424: The reconstruction money had been distributed, and those without land were locked out of financial support, exacerbating the social divide and feeding marginalization. Some disasters that came with the monsoon season were suspected to be related to the earthquake. There was a landslip on 11 June, killing 53 people. Meanwhile, a glacial lake had burst in the particularly hard-hit Solukhumbhu district. Whether or not

9030-506: The same region at 12:54 NST (07:08 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

9135-466: The seismic moment calculated from the observed physical dislocation. A double couple model suffices to explain an earthquake's far-field pattern of seismic radiation, but tells us very little about the nature of an earthquake's source mechanism or its physical features. While slippage along a fault was theorized as the cause of earthquakes (other theories included movement of magma, or sudden changes of volume due to phase changes ), observing this at depth

9240-430: The seismic waves generated by an earthquake event should appear in the "far field" (that is, at distance). Once that relation is understood it can be inverted to use the earthquake's observed seismic waves to determine its other characteristics, including fault geometry and seismic moment. In 1923 Hiroshi Nakano showed that certain aspects of seismic waves could be explained in terms of a double couple model. This led to

9345-498: The seismological parameter it is based on, is not measured routinely for smaller quakes. For example, the United States Geological Survey does not use this scale for earthquakes with a magnitude of less than 3.5, which includes the great majority of quakes. Popular press reports most often deal with significant earthquakes larger than M~ 4. For these events, the preferred magnitude is the moment magnitude M w  , not Richter's local magnitude M L  . The symbol for

9450-418: The standard scale used by seismological authorities like the U.S. Geological Survey for reporting large earthquakes (typically M > 4), replacing the local magnitude (M L  ) and surface-wave magnitude (M s  ) scales. Subtypes of the moment magnitude scale (M ww  , etc.) reflect different ways of estimating the seismic moment. At the beginning of the twentieth century, very little

9555-433: The surface waves are predominant. At greater depths, distances, or magnitudes the surface waves are greatly reduced, and the local magnitude scale underestimates the magnitude, a problem called saturation . Additional scales were developed – a surface-wave magnitude scale ( M s ) by Beno Gutenberg in 1945, a body-wave magnitude scale ( mB ) by Gutenberg and Richter in 1956, and a number of variants – to overcome

9660-459: The surface waves used in the measurement of M s  . This meant that giant earthquakes such as the 1960 Chilean earthquake (M 9.5) were only assigned an M s  8.2. Caltech seismologist Hiroo Kanamori recognized this deficiency and took the simple but important step of defining a magnitude based on estimates of radiated energy, M w  , where the "w" stood for work (energy): Kanamori recognized that measurement of radiated energy

9765-949: The time of the earthquake, although reports of foreign deaths were relatively low. A total of 78 deaths were reported in India – including 58 in Bihar, 16 in Uttar Pradesh, 3 in West Bengal and 1 in Rajasthan. Twenty-seven people were confirmed dead, 383 were injured and 4 were missing, all from the Tibet Autonomous Region . The quake destroyed 2,500 houses and damaged 24,700 others across 19 counties in Tibet , affecting nearly 300,000 people, among whom 47,500 were displaced, while A total of 82 temples were also damaged. The counties of Gyirong , Nyalam and Tingri in Xigazê were worst hit, where nearly 80 percent of

9870-445: The total energy, the rest being expended in fracturing rock or overcoming friction (generating heat). Nonetheless, seismic moment is regarded as the fundamental measure of earthquake size, representing more directly than other parameters the physical size of an earthquake. As early as 1975 it was considered "one of the most reliably determined instrumental earthquake source parameters". Most earthquake magnitude scales suffered from

9975-400: Was already derived by Hiroo Kanamori and termed it as M w . Eq. (B) was based on large earthquakes; hence, in order to validate Eq. (B) for intermediate and smaller earthquakes, Hanks and Kanamori (1979) compared this Eq. (B) with Eq. (1) of Percaru and Berckhemer (1978) for the magnitude 5.0 ≤  M s  ≤ 7.5 (Hanks and Kanamori 1979). Note that Eq. (1) of Percaru and Berckhemer (1978) for

10080-554: Was an area popular on the Langtang trekking route. The village of Langtang was destroyed by the avalanche. Smaller settlements on the outskirts of Langtang were buried during the earthquake, such as Chyamki, Thangsyap, and Mundu. Twelve locals and two foreigners were believed to have survived. Smaller landslides occurred in the Trishuli River Valley with reports of significant damage at Mailung, Simle, and Archale . On 4 May it

10185-506: Was announced that 52 bodies had been found in the Langtang area, of which seven were of foreigners. According to geological models, the frequency and intensity of future landslides in the Langtang Valley is due to increase in the coming decades. This is attributable directly to the effect of the earthquake, which caused widespread fracturing in the grounds of the Langtang area. Thousands of houses were destroyed across many districts of

10290-447: Was by Keiiti Aki for the 1964 Niigata earthquake . He did this two ways. First, he used data from distant stations of the WWSSN to analyze long-period (200 second) seismic waves (wavelength of about 1,000 kilometers) to determine the magnitude of the earthquake's equivalent double couple. Second, he drew upon the work of Burridge and Knopoff on dislocation to determine the amount of slip,

10395-462: Was expressed that harvests could be reduced or lost this season as people affected by the earthquake would have only a short time to plant crops before the onset of the Monsoon rains. Nepal, with a total Gross Domestic Product of US$ 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

10500-418: 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 (33 mi) as the crow flies from the epicenter. The second earthquake was somewhat less powerful at 6.6 M w  . It occurred 65 km (40 mi) east of Kathmandu and its seismic focus lay at a depth of 10 km (6.2 mi) below

10605-511: Was known about how earthquakes happen, how seismic waves are generated and propagate through the Earth's crust, and what information they carry about the earthquake rupture process; the first magnitude scales were therefore empirical . The initial step in determining earthquake magnitudes empirically came in 1931 when the Japanese seismologist Kiyoo Wadati showed that the maximum amplitude of an earthquake's seismic waves diminished with distance at

10710-571: Was not possible, and understanding what could be learned about the source mechanism from the seismic waves requires an understanding of the source mechanism. Modeling the physical process by which an earthquake generates seismic waves required much theoretical development of dislocation theory , first formulated by the Italian Vito Volterra in 1907, with further developments by E. H. Love in 1927. More generally applied to problems of stress in materials, an extension by F. Nabarro in 1951

10815-516: Was of low frequency, which, along with its occurrence at an hour when many people in rural areas were working outdoors, decreased the loss of human lives. The earthquake triggered an avalanche on Mount Everest , killing 22 people, the deadliest incident on the mountain on record. The earthquake triggered another huge avalanche in the Langtang valley, where 250 people were reported missing. Hundreds of thousands of Nepalese were made homeless with entire villages flattened across many districts of

10920-588: Was recognized by the Russian geophysicist A. V. Vvedenskaya as applicable to earthquake faulting. In a series of papers starting in 1956 she and other colleagues used dislocation theory to determine part of an earthquake's focal mechanism, and to show that a dislocation – a rupture accompanied by slipping – was indeed equivalent to a double couple. In a pair of papers in 1958, J. A. Steketee worked out how to relate dislocation theory to geophysical features. Numerous other researchers worked out other details, culminating in

11025-521: Was very similar to a relationship between M L   and M 0   that was reported by Thatcher & Hanks (1973) Hanks & Kanamori (1979) combined their work to define a new magnitude scale based on estimates of seismic moment where M 0 {\displaystyle M_{0}} is defined in newton meters (N·m). Moment magnitude is now the most common measure of earthquake size for medium to large earthquake magnitudes, but in practice, seismic moment (M 0  ),

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