Why would 5,000+ buildings crumble within seconds, as if they had no foundations?

by Rafaella Spanou

Not many days have passed since the devastating earthquake that shook the Turkish-Syrian border to its core. The death toll is rising exponentially with no signs of slowing down. As of the time this article was written, 12, 873 deaths have been registered in Turkey alone, and 3, 162 in Syria*. Rescue efforts are on-going. Turkish authorities have declared that 10 provinces and 13.5 million people have been affected by the earthquake. 13.5 million people no longer have a home to live in, many having watched them crumble to the ground within seconds. 

Was the earthquake that strong? No doubt. But it wasn’t solely responsible.

To better understand what happened, we asked Dr Daniel McCrum, Assistant Professor in Structural Engineering at UCD – whose research interests include earthquake engineering – what happens to a building when it’ s hit by an earthquake. According to Dr McCrum, as the ground moves, it shakes the building with huge force. The damage depends on the quake’s strength and duration, the distance from the epicentre and the construction of the building among other factors. Modern structural engineering designs ensure that the building will be able to resist this force of nature with as little damage as possible. 

“The sudden failure [seen] is called a pancake collapse where there is inadequate reinforcement in the reinforced concrete”, Dr McCrum explains.

In the past 25 years, since 1999, there have been 8 major earthquakes across Turkey, ranging from 6.1 magnitude to the most recent 7.8. So why is it that a country that is no stranger to earthquakes or their devastating aftermath, not have proper building structures to minimise the impact?

A USGS structural engineer told the Associated Press that the areas hit had mostly older buildings that were not built according to proper standards.

However, there is more to the story. After the 1999 earthquake that levelled Izmit and killed 17,000 people, Turkey implemented building codes to tackle the issue of illegal buildings across the country, to ensure any new building was quake-proof. And yet, in 2011’s earthquake, history repeated itself and more people died. Turkey’s then Prime Minister Recep Tayyip Erdoğan said “Municipalities, constructors and supervisors should now see that their negligence amounts to murder”.

Not long after, elected president Erdoğan passed a 2018 zoning amnesty law, that allowed builders to purchase a license to build – with no requirements for them to be quake proof. That decision generated a revenue of $3bn. 

But what happens now? So far, Turkey’s disaster management agency has confirmed 5,775 collapsed buildings of the 11, 342 reported. Dr McCrum explains that “If the buildings in Turkey had been appropriately seismically designed or retrofitted then fewer building collapses would have occurred”. 

The images of flattened cities and towns bare a striking resemblance to the photos of the 1999 Izmit earthquake, “where a post-earthquake field mission showed that inadequately designed and constructed buildings were the main reason for collapses”, according to Dr McCrum. The existence of structural design codes is of no use if they are not properly followed and implemented, he further explains.

For a building to survive a quake of that magnitude, the structure must be able to absorb the energy while remaining structurally intact. This is achieved by adding reinforcing steel in key locations of the building’s structure and using concrete of sufficient strength. The pictures and the extent of the damage appear to indicate that very few buildings met these criteria.

One of the great material losses of the earthquake, is the Roman-Era castle in Gaziantep and the 17^th century Şirvani Mosque – both tourist attractions of historical importance. Dr McCrum says that these buildings should have be seismically retrofitted to withstand the earthquake’s force.

Turkey and Syria sit between the Anatolian and Arabian tectonic plates, “a seismically active area known as the East Anatolian fault zone”, as scientists describe it. This will probably not be the last earthquake Turkey will experience, making the need for more proper infrastructure crucial, in order to avoid mass-casualties.

*The death toll has now risen over 50, 000.