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Update (Friday, Jan. 20): Ten people have been found alive at the hotel, while two dead bodies were also pulled from the wreckage, officials said, according to the New York Times.
After an avalanche buried an Italian mountain ski hotel, trapping up to 30 people under tons of snow Wednesday (Jan. 18), rescue workers launched a massive, complex effort to save the people buried underneath.
Investigators don't know exactly why the avalanche occurred, though a number of strong quakes and heavy snowfall "that hadn’t been recorded for decades," likely played a role, said Italian Prime Minister Paolo Gentiloni.
Rescue workers dug through massive snowdrifts, skied through a blizzard and worked through the night. So far, however, they've only recovered three bodies from the Hotel Rigopiano in Farindola, officials with the Italian government said.
"This is an enormously complex operation," Titti Postiglione, head of the Italian Department of Civil Protection's emergency office, told Reuters. [Top 10 Deadliest Natural Disasters in History]
But how will rescue workers find the people buried inside the hotel, and what affects their odds of survival?
"When you start to add structures to the mix, then it can get highly complicated, trying to find people." said Simon Trautman, a national avalanche specialist with the U.S. Forest Service's National Avalanche Center in Bellingham, Washington.
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Survival odds will likely depend on the immediate surroundings of the people who were buried, as well as possibly what they were wearing, Trautman added.
Rare occurrence
In the United States, just a handful of cities, such as Telluride, Colorado; Ketchum, Idaho; and Juneau, Alaska, face a serious risk that avalanches will bury structures, Trautman said.
As such, most avalanche specialists focus on saving backcountry skiers or snowmobilers who have been buried in snow, Trautman said.
"In that scenario, you have a very small time window to get to somebody," Trautman said. "However, it's fairly simple; you have a person in a pile of snow."
To hasten the time to rescue, backcountry skiers often wear a receiver that sends out a radio signal to a skiing partner. The receiver can instantly provide location information to help them be dug out quickly. Others may wear a reflective device called a Recco that reflects back to a person who is searching for them. [The 7 Most Dangerous Places on Earth]
In such a scenario, finding a person is a matter of timing. A person who has no other injuries and has been buried for less than 15 minutes has a greater than 90 percent chance of surviving, whereas just one in three people trapped for 35 minutes will be rescued alive, according to avalanche.org.
Keeping rescuers safe
However, in the case of the Hotel Rigopiano, located in the Gran Sasso mountains, the situation is much more complicated.
"The thing that really jumped out at me [while] watching the video is just how much work they're having to do just to reach the hotel alone," Trautman said.
The rescue team, which is being run by Lazio's Alpine and Speleological Rescue Team, faced blizzard conditions, and there is no guarantee that more quakes, and avalanches, aren't on the horizon, Trautman said.
Once the rescue workers get close to the structure, they have to move tons of snow. During an avalanche, snow is moved around a lot; when it settles again, it forms additional bonds, making it denser, Trautman said.
"A cubic meter of dense snow can be almost a thousand pounds," Trautman said. "It's not light and fluffy. It's very heavy."
However, machines or mechanical devices that are used to move lots of snow also run the risk of injuring people who may be buried beneath the heavy veil, Trautman said.
"It may be one of those things where 10 people with shovels is safer and faster," Trautman said.
No sign of life
Once rescuers reach the building, the structure can impede radio and reflective signals; and, in any case, the people at the hotel weren't wearing any kind of homing devices, Trautman said. In these scenarios, rescue crews use dogs that are trained to detect the scent of people.
However, although a rescue is more complicated when a building is involved, the structure could actually provide some hope for survival.
The odds of survival depend on whether the snow entered or destroyed the building, whether a person is bundled up and wearing warm clothes at the time of the avalanche, and whether they are actually buried by snow. The avalanche destroyed part of the roof and rocked the building on its foundations, the BBC reported, while other reports say the building is almost completely destroyed and choked with snow, Reuters reported.
"If people survive the initial blow, then there are higher chances of people living," Trautman told Live Science. "If they get pushed into a corner or behind a couch and they have an air pocket or some space, they could survive for quite some time."
The main key for survival is the size of the air pocket, said Ben Pritchett, the program director for the American Institute for Avalanche Research and Education in Colorado.
"The size of that air pocket is really going to determine how long they might live, and certainly probabilities begin to drop off fairly soon after the event," Pritchett told Live Science. "But there's examples of people being buried in structures surviving for hours for even a short number of days."
Either way, it's certain that the rescue team hasn't given up hope of finding survivors, Pritchett said. At this point, rescue workers have made it into the lobby and have called out but gotten no reply, Reuters reported.
Originally published on Live Science.
Tia is the editor-in-chief (premium) and was formerly managing editor and senior writer for Live Science. Her work has appeared in Scientific American, Wired.com, Science News and other outlets. She holds a master's degree in bioengineering from the University of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor's degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Journal Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.