When an avalanche thundered down Mount Everest last weekend, guides tweeted calls for help and dramatic video footage quickly went viral as trekkers accessed wifi on the roof of the world.

When Edmund Hillary and Tenzing Norgay reached the summit of the world's highest mountain 62 years ago, news didn't reach the outside world until four days afterwards and no photographs of Hillary were taken at the top.

"As soon as I spoke with colleagues and realised the impact of this snow tsunami, I tweeted about it so we could get help to deal with this huge disaster," said veteran guide Dan Mazur.

The 7.8-magnitude quake that struck Nepal Saturday, killing more than 6,700 people, sent a cascade of snow tearing through Everest base camp, leaving more than a dozen dead and scores injured.

Within minutes reports and photos of the disaster were circulating widely across social media, largely due to the actions of mountaineers like Mazur, sparking relief operations into action and helping save lives.

"A Massive earthquake just hit Everest. Basecamp has been severely damaged. Our team is caught in camp 1. Please pray for everyone," the American posted on Twitter, moments after the avalanche roared past.

The contrast to the news emerging of Hillary and sherpa Tenzing's monumental feat in becoming the first climbers to reach the top of the 8,848-metre (29,029-foot) high mountain in 1953, could not be more stark.

They arrived at the summit on the 29 May but word did not reach London until June 2, just in time for Queen Elizabeth II's coronation.

No pictures were taken of Hillary at the top, apparently because Tenzing did not know how to work a camera. But in his autobiography the New Zealander claimed it had never occurred to him to ask for a picture.

Today, the hundreds of tech-savvy climbers who attempt Everest every year are armed with smartphones, iPads and laptops that they use to live-tweet their ascents to a global audience.

AFP Roberto Schmidt sent his dramatic photograph of the avalanche via a Broadband Global Area Network (BGAN) terminal.

- Summit sharing -

Mazur, 55, said he initially perceived social media as an easy way for climbers and staff to communicate with their families during expeditions but eventually came to appreciate its value as a safety tool.

"When I first started climbing in the Himalayas 25 years ago, it would have been days before people would have realised that an accident had occurred and sent help," he told AFP from Everest base camp.

"When I think about the fact that I am in base camp right now using a mobile phone to talk to a journalist in Kathmandu, I have to say it's pretty amazing in terms of getting the word out," Mazur added.

Mountaineer Adrian Ballinger's company, Alpenglow Expeditions, provides clients with 18 hours of wifi a day at altitudes where atmospheric oxygen drops to dangerously low levels.

They have 36 solar panels powering eight generators and climbers are able to charge 40 devices at the same time.

"Climbing used to be this solitary experience, but people are very interested in sharing their journey now, whether it's through Twitter, Facebook, WhatsApp," Ballinger told AFP.

"The big difficulty is managing the power supply -- we use solar power but we also need to carry these bulky batteries and systems as we go up mountains," he said.

As well as the ability to send an SOS call, wifi provides better access to weather forecasts and opportunities for climbers to attract sponsorship deals in a crowded marketplace.

In October 2010, US adventurer Eric Larsen became the first person to tweet from the roof of the world when he sent out the message, "Everest summit!" with a reference to his sponsor -- satellite communication company DeLorme.

Soon afterwards, Nepalese telecom group Ncell set up a station providing a high-speed third-generation (3G) phone network at an altitude of 5,200 metres, offering Internet services to anyone with a smartphone.

"All this technology is helpful in terms of letting people know you are safe when something terrible happens," said the British Ballinger.

"On the other hand, in this hyper-connected age, I find that people tend to panic if they don't hear from you immediately because they expect you to always be online."

Key facts about the Nepal quake, one week on
Kathmandu (AFP) May 2, 2015 - A week on from a 7.8-magnitude earthquake that struck Nepal, flattening large parts of the capital Kathmandu and causing devastation across the impoverished Himalayan nation, here are some key facts about the disaster.

- Death toll -

- 6,621 people are known to have died in Nepal alone and 14,023 others were injured

- More than 100 people were killed in neighbouring India and China

- 18 climbers died at Mount Everest base camp when the quake sparked an avalanche

- Two Americans, an Australian, a Japanese and a Chinese national were among the victims on the mountain

- 1,000 European Union citizens are missing, the EU says

- 12 others from EU countries have been confirmed dead

- Survivors -

- Eight million people, or around a quarter of Nepal's population, have been affected, the United Nations estimates

- 2.8 million Nepalese were displaced

- More than 3.5 million people are estimated to be in need of food assistance

- 1.7 million children are in need of humanitarian aid in the worst-hit areas, according to UNICEF

- Aid -

- Rescuers from 22 countries are involved in the relief effort while $61 million has been pledged, according to the UN

- Britain has promised $15 million

- $12.5 million has been pledged by the United States

- $15 million is being released from the UN's emergency fund

- The UN has appealed for $415 million while UNICEF is seeking to raise $50.35 million

- The United Nations' Food and Agricultural Organization has appealed for $8 million for farmers

- The World Food Programme says it needs US$116.5 million to provide food for 1.4 million people

- Reconstruction -

- 160,786 homes were destroyed and another 143,673 damaged

- The UN says that up to 90 percent of health facilities in four districts were severely damaged

- Some 16,000 schools were damaged

- Reconstruction costs could top $5 billion -- around 20 percent of the country's GDP -- according to business research consultancy IHS