Images of collapsing and collapsed buildings are really distressing.
After all, structural failure is what causes the earthquake’s catastrophic death toll.
Hence, why is it so difficult in an area with known risk?
This was, above all, a very serious earthquake. This earthquake was possibly even more destructive than what even Turkey’s experienced and knowledgeable seismic risk scientists had predicted in worst-case scenarios.
This is evident from Turkey’s seismic sensor network, which measures ground shaking during earthquakes. In this case, it was around the East Anatolian Fault that caused the disaster.
Although data is preliminary and could be corrected, some of the highest readings from these sensors may exceed the limits of shaking as set forth in Turkey’s earthquake design codes.
These buildings must be able to withstand the severe shaking that is expected to occur every 475 years. And resist collapsing in a once-every-2,475-year event.
Some sensors however recorded peak ground accelerations of over 7m per squared, which is a crucial measure of earthquake force.
Turkey – Syria earthquake – latest updates
Experts believe these values are higher than the earthquakes that could occur in these regions, even in the rarest of earthquakes.
“Even very well-designed and very well-executed buildings will have to suffer and be challenged,” says Professor Yasemin D. Aktas, University College London structural engineer.
She adds that “but this doesn’t exclude the building stock we see collapsing was without defects and problems.”
Here are more news:
A woman whose family was destroyed tells Sky News, “I wish I’d die and my children had survived.”
John Sparks – Searches for signs and life in Kahramanmaras (the Turkish city at the epicenter).
Alex Crawford: The pace of rescue operations in one of the most affected areas has dramatically changed
Gaziantep, located 70 km from the epicenter of the earthquake, is a good example. It suffered less severe shaking.
There were many large buildings that collapsed into rubble, or they “pancaked”, with floors still intact but falling on top of each other.
Gaziantep was also at risk. A team of Turkish hazard specialists used risk maps last year to identify areas where older or poorly constructed buildings pose a serious earthquake risk.
Their modelling assumed that a quake would strike 10 times less than the one that occurred Monday morning.
It is important to note that there was not just one major earthquake. There were two. Nine hours later, a magnitude 7.5 aftershock followed the first earthquake. Some buildings that survived were destroyed by the second shock.
Many more buildings survived the disaster, but they are severely damaged. This presents a significant challenge to authorities in dealing with the aftermath.
Tens of thousands of survivors have been left homeless. However, many thousands more are not able to return to their homes, which may be still standing but damaged beyond repair.
A special program called Disaster Zone: The Turkey–Syria Earthquake will air on Sky News Friday night at 9.30pm