Search and rescue in urban disaster zones is a methodical process often conducted jointly by local emergency management authorities and international teams. Speed is essential as people trapped in the rubble often struggle to survive for longer than a few days. And the area hit by the disaster can be vast. Rescue workers also look for and document survivable void spaces, such as stairwells or areas beneath beams. In some cases, people have survived in spaces like this for days.
If the space is big enough for a person to crawl through, the chances of survival are higher. Small voids are more dangerous as people trapped inside have less space to avoid further movement of debris or collapsing structural elements.