Writing in The Conversation, an Australian news website, Mark Quigley, associate professor of earthquake science at the University of Melbourne said that many of the modern buildings that failed did so in a "pancake mode" of structural collapse.
At least 3,450 buildings have collapsed, according to current estimates by the Turkish government.
Two earthquakes hit south-central Turkey and western Syria on Monday 6th February. The first measured 7.8 in magnitude and was felt as far away as the UK. The second occurred nine hours later, on what appears to be an intersecting fault, registering a magnitude of 7.5.
Earthquakes are common in Turkey which sits on the East Anatolian Fault zone, a very seismically active region where three tectonic plates constantly grind against one another beneath the Earth's surface.
Many of the collapsed buildings appear to have been built from concrete without adequate seismic reinforcement, according to Quigley:
“Seismic building codes in this region suggest these buildings should be able to sustain strong earthquakes (where the ground accelerates by 30% to 40% of the normal gravity) without incurring this type of complete failure.
“The 7.8 and 7.5 earthquakes appear to have caused shaking in the range of 20% to 50% of gravity. A proportion of these buildings thus failed at shaking intensities lower than the design code," said Quigley.
Similar building collapses have been seen in past earthquakes in Turkey.
In 1999, a huge quake near Izmit killed around 17,000 people and destroyed as many as 20,000 buildings.
After a quake in 2011 in which hundreds of people died, Turkey's then prime minister, Recep Tayyip Erdogan, blamed shoddy construction for the high death toll, saying: "Municipalities, constructors and supervisors should now see that their negligence amounts to murder."
Prof Quigley said: “Many of the buildings are already built, and seismic retrofitting may be expensive or not considered a priority compared to other socio-economic challenges.
“Earthquakes are likely to have caused myriad environmental effects, such as ruptured ground surfaces, liquified soil and landslides. These effects may render many areas unsafe to rebuild on – so reconstruction efforts should also include planning decisions about what can be built where, to lower future risks”.
This story is edited from The Conversation under a Creative Commons license. Read the original article.
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