Nepal has been hit by a number of earthquakes over the years, as you might expect given its proximity to Everest and the world’s tallest mountain range created by the collision of two giant tectonic plates.

But this time, the devastation was much greater than usual, as the country fell victim to its biggest seismic event in 80 years.

The first problem was the power of the quake, coming in at magnitude 7.8, which one expert described as similar to having 20 thermonuclear hydrogen bombs – each many times greater than the atomic bomb that devastated Hiroshima – ripping through the Kathmandu Valley.

Second, the epicentre of the earthquake was only 40 miles to the north-west of the most highly populated part of Nepal, the capital city of Kathmandu.

Powerful earthquake hits Nepal Show all 44 1 /44 Powerful earthquake hits Nepal Powerful earthquake hits Nepal Earthquake hits Nepal Victims of the earthquake are cremated at Pashupatinah Temple in Kathmandu Getty Images Powerful earthquake hits Nepal Earthquake hits Nepal An elderly woman prays at a temple in Kathmandu damaged by the earthquake AP Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese police push back residents who began protesting after waiting for hours in line to board buses back to towns and villages Getty Powerful earthquake hits Nepal Earthquake hits Nepal A Nepalese policeman guards a collapsed building in Kathmandu. The number of people killed in the earthquake has passed 5,000 according to official figures EPA Powerful earthquake hits Nepal Earthquake hits Nepal A woman stands in silence in front of the historic Bal Krishna Thapa Chhetry temple in Kathmandu, which was been damaged by the earthquake EPA Powerful earthquake hits Nepal Earthquake hits Nepal Rescuers from Japan in the centre of Kathmandu; they are facing a race against time to find survivors Getty Powerful earthquake hits Nepal Earthquake hits Nepal Pallets of Australian aid (blankets, tarpaulins, hygiene kits and water purification tablets) are loaded onto a No. 36 Squadron C-17A Globemaster aircraft in preparation for delivery to Nepal Getty Images Powerful earthquake hits Nepal Earthquake hits Nepal Rishi Khanal is rescued after being trapped in a collapsed building in Nepal’s capital following Saturday’s earthquake Reuters Powerful earthquake hits Nepal Earthquake hits Nepal Villagers shelter from rain in the Gorkha district, north-west of Kathmandu; 10 days of rain are forecast, with tens of thousands of people sleeping outdoors AFP/Getty Powerful earthquake hits Nepal Earthquake hits Nepal A prayer bell is seen on top of the rubble of a damaged temple after an earthquake in Kathmandu, Nepal Reuters Powerful earthquake hits Nepal Earthquake hits Nepal People search through the rubble at the earthquake damaged Durbar Square in Kathmandu. Hundreds of thousands of Nepalis spent another night in the open after a massive quake which killed more than 4,000 AFP/Getty Powerful earthquake hits Nepal Earthquake hits Nepal A priest prepares a fire for the cremation of an earthquake victim at Pashupati cremation center in Kathmandu, Nepal. The official death toll from the magnitude 7.8 earthquake has risen to 5,057 people EPA Powerful earthquake hits Nepal Earthquake hits Nepal A Nepalese villager injured in an earthquake holds her son as they sit inside an Indian Army helicopter after being evacuated from Lapu in Gorkha AFP/Getty Powerful earthquake hits Nepal Earthquake hits Nepal A satellite image showing a part of the city's historic center, left, before the 25 April 2015 earthquake and the after effects, right EPA Powerful earthquake hits Nepal Earthquake hits Nepal An injured woman and her daughter receive medical treatment after arriving at Dhading hospital, in the aftermath of the earthquake, in Dhading Besi Powerful earthquake hits Nepal Earthquake hits Nepal An elderly woman mourns in front of her destroyed home in the Kumalpur village, on the outskirts of capital Kathmandu Powerful earthquake hits Nepal Earthquake hits Nepal Earthquake victims collect belongings and salvage food items from a destroyed building after a major earthquake, Kumalpur village, on the outskirts of capital Kathmandu Powerful earthquake hits Nepal Earthquake hits Nepal A Nepalese girl injured in the earthquake holds the hand of her mother inside an Indian air force helicopter as they are evacuated from Trishuli Bazar to Kathmandu airport in Nepal Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese victims of the earthquake lie inside an Indian air force helicopter as they are evacuated from Trishuli Bazar to Kathmandu airport in Nepal Powerful earthquake hits Nepal Earthquake hits Nepal An injured boy sleeps on the ground outside the overcrowded Dhading hospital in Dhading Besi Powerful earthquake hits Nepal Earthquake hits Nepal Members of a rescue team from China huddle while planning their operation at the site of earthquake in Kathmandu Powerful earthquake hits Nepal Earthquake hits Nepal Local people gather at the top of large mound where once stood a temple to view the scene of devastation in Kathmandu Powerful earthquake hits Nepal Earthquake hits Nepal People pray before cremating the body of a victim of the earthquake, along a river in Kathmandu, Nepal Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese soldiers carry a wounded man on a makeshift stretcher to a waiting Indian air force helicopter as they evacuate victims of the earthquake from Trishuli Bazar to Kathmandu airport in Nepal Powerful earthquake hits Nepal Earthquake hits Nepal An Indian Air Force person carries a Nepalese child, wounded in the earthquake, to a waiting ambulance after the child and mother were evacuated from a remote area at the airport in Kathmandu Powerful earthquake hits Nepal Earthquake hits Nepal An Indian Air Force person walks carrying a Nepalese child, wounded in the earthquake, to a waiting ambulance as the mother follows after they were evacuated from a remote area at the airport in Kathmandu Powerful earthquake hits Nepal Earthquake hits Nepal Indian resident Santosh (2L) is met by relatives after being evacuated following an earthquake in Nepal at the railway station in Amritsar Powerful earthquake hits Nepal Earthquake hits Nepal A helicopter prepares to rescue people from camp 1 and 2 at Everest Base Camp, Nepal Powerful earthquake hits Nepal Earthquake hits Nepal People carry a woman from the rubble of a destroyed building after an earthquake hit Nepal, in Kathmandu, Nepal EPA Powerful earthquake hits Nepal Earthquake hits Nepal People try to free a living man from the rubble of a destroyed building after an earthquake hit Nepal EPA Powerful earthquake hits Nepal Earthquake hits Nepal A man struggles to free himself from under the rubble of a destroyed building after an earthquake hit Nepal, in Kathmandu, Nepal EPA Powerful earthquake hits Nepal Earthquake hits Nepal People free a man from the rubble of a destroyed building after an earthquake hit Nepal, in Kathmandu, Nepal EPA Powerful earthquake hits Nepal Earthquake hits Nepal Dust can be seen over the city during an earthquake in Kathmandu, Nepal, 25 April 2015. EPA Powerful earthquake hits Nepal Earthquake hits Nepal A building stands damaged after an earthquake in Kathmandu, Nepal, Saturday, April 25, 2015 AP Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese people walk past a collapsed building in Kathmandu on April 25, 2015. AFP/Getty Images Powerful earthquake hits Nepal Earthquake hits Nepal An injured man is assisted after an earthquake caused serious damage in Kathmandu, Nepal, 25 April 2015. EPA Powerful earthquake hits Nepal Earthquake hits Nepal An injured child lies on the ground outside the Medicare Hospital in Kathmandu, Nepal, Saturday, April 25 AP Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese health workers carry injured people into an open area following an 7.9 earthquake, at Lalitpur on the outskirts of Kathmandu on April 25, 2015. AFP/Getty Images Powerful earthquake hits Nepal Earthquake hits Nepal Indian bystanders look at a collapsed house following an earthquake, in Siliguri on April 25, 2015 AFP/Getty Images Powerful earthquake hits Nepal Earthquake hits Nepal Volunteers help with rescue work at the site of a building that collapsed after an earthquake in Kathmandu, Nepal, Saturday, April 25 AP Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese rescue members and onlookers gather at the collapsed Darahara Tower in Kathmandu on April 25, 2015. AFP/Getty Images Powerful earthquake hits Nepal Earthquake hits Nepal People search for survivors stuck under the rubble of a destroyed building, after an earthquake caused serious damage in Kathmandu, Nepal, 25 April 2015. EPA Powerful earthquake hits Nepal Earthquake hits Nepal Nepalese rescue members move the body of a victim from the collapsed Darahara Tower in Kathmandu GETTY Powerful earthquake hits Nepal Earthquake hits Nepal Health workers take care of injured people outside the Manmohan Memorial Community Hospital after an earthquake caused serious damage in Kathmandu, Nepal EPA

Further compounding the impact was the shallowness of the earthquake, at just 10 to 15km below ground, meaning that the shaking was felt much more strongly. Deeper quakes have more earth to absorb the shaking.

Earthquakes are typically followed by a flurry of aftershocks, which tend to reduce in strength and frequency as time goes on. These can be

felt hundreds of miles away. One such aftershock occurred just half an hour after the main earthquake, with a magnitude of 6.6, and more than 20 others have followed since.

The concern is that, although the magnitudes deteriorate, they can continue to inflict significant damage on buildings already weakened by previous activity.

Nepal is particularly susceptible to earthquakes because of its position at the junction of the two giant tectonic plates that push Everest and the rest of the Himalayan mountain range a few millimetres higher every year.

The upward climb of the world’s highest mountain range is accompanied by numerous tremors as one giant slab of rock – the Indian tectonic plate – moves northwards at a rate of two inches a year, pressing up against another great slab – the Eurasian tectonic plate – in the process, which geologically speaking is very fast.

As the plates push against each other, friction generates stress and energy that builds until the earth’s crust ruptures. It is this movement that triggered the quake.