Step one - analysis

Once in the disaster area, the first step is to analyze the task at hand,

In a collapsed building, "you need to analyze the building, assess its history and try to establish where in the building people are most likely to be, "You also need to determine how badly a building has been damaged and whether it is likely to collapse any further, causing damage to [survivors] and rescue teams."

The assessment also involves checking for hazards such as downed power lines, gas leaks, flooding and hazardous materials. Protective gear includes special suits, gloves, masks, and oxygen and carbon monitoring systems for air quality.

Step two- search mode

At its most basic, this involves trying to spot limbs in the rubble, and calling out to survivors to identify their locations.

Rescuers look for "voids", or pockets where people may be trapped when walls collapse or where survivors may have hidden, such as under desks, in bath tubs or stairwells.

feed a camera on the end of a flexible pole into the collapsed building - this shows where people are and how much of the building's structure is left,.

"Rescuers also use sound location devices connected to a microphone system; the device bangs on the rubble three times and if people tap back or call out for help, they can be tracked and assisted.

Listening is a crucial part of the operation, and search teams will often stop for several minutes to try to hear any calls, scratches or taps.

Other search tools include a thermal image camera system, which shows areas of body heat, and trained sniffer dogs. "We also use a carbon dioxide analyzer, which helps us detect people who might be unconscious but still breathing

As survivors are found, rescuers try to get them to keep talking to determine their exact location, and dig towards them - the least dangerous way to do this is by hand.

Step three - the rescue operation

If survivors are trapped under rubble, it may need to be stabilized first; a process called cribbing - the construction of a rectangular wooden framework, a box crib, underneath the debris - may be used.

Survivors who are not able to move usually need to be lifted, dragged or carried out of the rubble using special equipment.

"If people cannot be manually dug out, then we can cut them out - there are specialized tools that can cut through concrete, metal and wood to reach survivors, "There is also a process known as 'slabbing', where heavy slabs of concrete are removed in order to free survivors - this is always a very difficult judgment call, because it risks further collapse, which could injure or kill more people

Search and rescue teams usually start the most urgent medical procedures on Concrete saws, jackhammers, chainsaws, bolt cutters, cranes and bulldozers are all part of the tool kit; chains, cables, anchors and rope-hauling systems are used to remove large pieces of masonry. Other equipment may include flat bags that are inserted under heavy objects and inflated with an air pump, and "shoring" equipment, which ensures passageways are stable and safe.

As survivors are removed, their medical condition is determined; patients are prioritized according to triage - based on the severity of their condition.

Search and rescue teams usually start the most urgent medical procedures on site; the most experienced teams may have defibrillators and endo-tracheal equipment to shock people back to life or perform emergency tracheotomies.

Step four - closure

Deciding when to end a rescue operation is always difficult.

"Obviously, the more time passes the less likely you are to find people alive, "But sometimes - especially if they have water available - people can remain alive for many days.