How long can survivors last under rubble?

media captionHow have people rescued from rubble days after an earthquake survived so long?

A six-month-old girl has been rescued from a building four days after it collapsed in the Kenyan capital, Nairobi.

BBC News examines how people stay alive under rubble - and what dictates the duration of search operations.

The UN usually decides to call off search and rescue attempts between five and seven days after a disaster, once no-one has been found alive for a day or two. However, people have been known to survive for much longer.

In May 2013 a woman was pulled from the ruins of a factory building in Bangladesh, 17 days after it collapsed. Workers heard her crying out "please save me" and used video and audio detection equipment to locate her exact position.

After the Haiti earthquake in January 2010, one man survived for 12 days under the rubble of a shop that had been repeatedly looted. At least 200,000 people died in the disaster.

Another extraordinary case in December 2005 saw a 40-year-old woman saved from what had been her kitchen in Pakistani-administered Kashmir, more than two months after an earthquake hit the region.

Doctors said it was a miracle that Naqsha Bibi had survived so long in a space so small she could not move.

image copyrightReuters
image captionRescuers celebrate finding survivor Pema Lama in Kathmandu


Julie Ryan, a co-ordinator with UK-based group International Rescue Committee (IRC), says that survival largely depends on what happens the moment the quake first hits or a building collapses.

"The ideal situation is you have become trapped and entombed but have some sort of oxygen supply from the outside world, are not injured and also have some sort of access to water," she told the BBC.

"You have usually managed to get yourselves into some sort of void where you are enclosed by the building but it doesn't injure you."

She said an IRC team rescued three boys who had been buried in the ruins of their school for five days after the earthquake in Pakistan in 2005.

"They were laid flat on their backs next to each other, with the ceiling touching their noses but totally unhurt," she said. Another boy alongside them had died.

After so long in the dark, rescue teams had to cover the boys' eyes as they pulled them out, to protect them from the strong sunlight.

image copyrightAP
image captionReshma Begum was pulled from the rubble of the Rana Plaza Factory in Dhaka in May 2013 after 17 days

'Crush syndrome'

Dr Tejsrhi Shah of Medecins Sans Frontieres says those suffering from injuries to their bodies can suffer from crush syndrome. This happens when tissue is compressed and dies.

When the pressure is released, a build-up of toxins from muscle breakdown floods the body and it is unable to cope.

"It causes renal damage and shock, people are in agony with the pain and have a high risk of developing renal failure if [they] don't get urgent medical care," she said.

Dr Shah said reports of people surviving in rubble for longer than two weeks were "incredibly rare".

"The chances of getting someone out alive decreases with each day."

Being trapped in a confined space also means a rising temperature and an increase in carbon dioxide, which, if it reaches too high a level, leads to suffocation.

Search teams monitor for rising levels of CO2 in a building - a rise means someone is trapped inside and breathing. When CO2 levels stop rising, the search is likely to prove fruitless.

media captionThis man was pulled from an apartment block in Kathmandu. Yogita Limaye reports

Graham Payne, chairman and founder of rescue charity Rapid, told the BBC trapped people could go quiet for hours at a time if they passed out or fell asleep but teams never gave up on them.

"You think you've lost them but you carry on. It might be another eight hours, then they start making noise again.

"But if they're trapped and we can hear, then we get them out, we don't give up."

Sheer determination

If you are uninjured, have an air supply and are in an adequate space - however small - the next priority is water.

Dr Shah says estimating how long people can survive without water is the "million dollar question", but that the average is between three and seven days.

"It depends on the ambient temperature, how much fluid you're losing through sweat, if you have diarrhoea, how healthy you are, how old you are," she says.

image copyrightBONNY ODHIAMBO
image captionSeven-month-old Dealeryn Saisi Wasike was rescued four days after building collapsed in Nairobi

Dr Ian MacOnachie, an expert in emergency medicine and clinical standards at the UK's Royal College of Paediatrics and Child Health, said that, in babies, up to 90% of their bodies were made up of water, acting as a "natural storage" in cases of dehydration.

Therefore, he said, it was not a "complete surprise" that babies could survive for days, like the one in Nairobi.

He also noted that, no matter the age, the level of injuries was a key factor in someone's chances of survival.

Additionally, a few fortunate people may find themselves trapped with a clean supply but others will find a trickle of rainwater, condensation or even use water from inside radiators.

Despite the best preparation and advice, rescuers say survival often comes down to "sheer determination".

"It's the will," says Mr Payne. "Some people just accept they are trapped and it's fate. Others just keep going."

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