How rescuers tackle collapsed buildingsContinue reading the main story
Rescue workers need to be swift to assess where they are most likely to find survivors inside collapsed buildings. Stairwells or the spaces under large concrete beams can provide what rescue workers call voids. It is in places like these that the living can be found.
Local people often know the best locations to begin the search for survivors and can also give vital information about when the collapse happened and who might be inside. After speaking to them rescue workers can quickly select the most promising place to begin their work. The first job then is to assess the building for safety so that the rescuers do not themselves become trapped.
Specialist sound equipment can detect the faintest of noises to within a few metres. Silence on the site is needed while a member of the rescue team bangs three times and hopes to hear a response. Carbon dioxide detectors can be used to find survivors rendered unconscious. They work best in confined spaces where they detect the greater CO2 concentration in the air exhaled by those still breathing.
Video cameras placed on the end of flexible poles can be squeezed through gaps in the rubble to help locate survivors. Using this technique means time is saved as less rubble is shifted unnecessarily. Thermal imaging equipment can be used to locate people not directly in a line of sight as their body heat can warm the rubble around them.
Dogs are extremely effective at using their sense of smell to pick up on signs of life that human rescuers cannot. They are also able to cover large areas quickly, speeding up the search and rescue process.
Digging by hand
Heavy-lifting equipment can be in short supply or roads blocked, leaving rescuers little option but to shift rubble by hand or with pick-axes and shovels. Other tools include chainsaws, disc-cutters and rebar cutters - which can be used to tackle the metal bars in reinforced concrete. However sparks from this equipment can cause fire if they ignite ruptured gas pipes or other fuel.
Ending the rescue
In earthquakes, the co-ordinating agency, usually the UN, and the host country, have to take the difficult decision of when to stop looking for a few remaining trapped people and concentrate resources on looking after other survivors. The average time for this switch is between five and seven days, but individuals have been known to survive as long as 13 days trapped if they have access to water.
Heavy lifting equipment
Diggers and hydraulic jacks are among the heavy machinery that rescue workers employ to shift rubble. Large concrete slabs on the outside of buildings can be pulled aside by diggers, enabling rescuers to get a view of any people still trapped inside.
When faced with a collapsed building, whether from an earthquake or another cause, rescuers know they have a finite time to pull people out alive.
Explore this clickable guide, put together with information from International Rescue Corps, to find out the methods used by emergency response teams when disaster strikes.