Governments and international organizations from around the world have responded with offers of support after a major earthquake of magnitude 7.8 struck central Turkey and northwest Syria, the world’s deadliest tremor in at least a decade.

Two days after the quake, Turkish President Tayyip Erdogan admitted relief had been slow to arrive.

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.

The International Search and Rescue Advisory Group (INSARAG), a network of countries and organisations under a U.N. umbrella, helps facilitate coordination between international search and rescue teams that deploy in such disasters.

Its guidelines describe distinct phases in organizing major multinational search and rescue operations.

Wide area assessment

A preliminary survey of the affected area is often carried out by local emergency teams while additional help arrives. The destruction may just involve one city, or it may encompass a large area involving numerous towns across more than one country, as with the latest quake. Teams conducting the initial visual assessment remain mobile - traveling quickly by air or road, if the infrastructure permits - and don’t engage in rescue operations.

The survey helps to identify possible resources and hazards, as well as the main priorities for search and rescue teams. The disaster area is often then drawn into sectors to allocate command and to assign search teams.

Worksite triage

This assessment identifies viable live rescue sites in an allocated sector. The command center uses this information to prioritise rescue sites and decide which teams to deploy where. Emergency teams aim to assess the entire sector as quickly as possible.

At each site, rescuers seek to gather essential information such as building size, type of construction materials and the “building collapse category”, aimed at classifying the different types of damage and danger.

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.

Similarly, rescue workers should look for dangers like downed power lines, gas leaks, flooding, and other hazards. Rescuers should use protective equipment, such as special suits, gloves, masks, and air quality monitoring devices.

Rapid search and rescue

In the early stages of a major earthquake response, when a large number of sites need checking, emergency teams conduct rapid searches to maximise the opportunities for saving lives. Teams are usually done at a site within a few hours, then move to the next.

Rescuers can use this stage to identify sites where a deeper search could be worthwhile. Specially trained dogs can be used to sniff out signs of life, moving quickly in the rubble.

Sound signalling

In major disasters - such as the 2021 temblor in the Caribbean nation of Haiti - where teams from many countries are present, language barriers mean that effective emergency signaling is essential for safe operations at the disaster site. All emergency personnel must know how to react to the sound signals, usually from air horns or other hailing devices.

Full search and rescue

This phase of operations locates and rescues a smaller number of trapped survivors who local rescuers, first responders, or level 3 operations could not reach. Rescue teams try to penetrate most or all of the survivable voids left inside collapsed structures. The process can involve multiple teams and last several days.

Carbon dioxide detectors and thermal imaging equipment can be used to find survivors, even if they are unconscious. Specialised teams can employ sensitive sound equipment to detect movement within buildings, while tiny video devices may be used to locate people buried beneath the rubble. Often debris must be removed by hand to avoid crushing survivors by using heavy equipment.Below are some of the smaller types of rescue equipment that may be used by rescue teams.

Search and rescue teams have worked day and night in cold, wet weather while also facing the threat of aftershocks. Rescuers have found some people alive in the rubble but many Turks have complained of a lack of equipment, expertise and support to rescue those trapped - sometimes even as they could hear cries for help. Amid the devastation, there have been reports of dramatic rescues across central Turkey and northwest Syria.

Recovery

Usually carried out after rescue efforts have been abandoned, the recovery phase may include the removal of large rubble piles and recovering bodies. This work can be carried out by local teams after international rescue workers have departed. Using heavy machinery and demolition equipment, teams try to access all voids left within collapsed structures.

The difficult decision of when to stop searching for trapped survivors is made by the coordinating U.N. agency and the state. Victims have been found to survive for more than two weeks trapped under rubble if they have access to water. However, search and rescue attempts are usually halted around a week after a disaster if no-one has been found alive in the previous day or two.