Why was the destruction to buildings in Turkey so catastrophic?
The images of collapsed, and collapsing buildings are truly distressing.
After all, structural failure is the main reason for the catastrophic loss of life in this earthquake.
So why has it been so bad in an area of known risk?
Above all else, this was a very severe earthquake. Possibly even more severe than even Turkey’s knowledgeable and experienced seismic risk scientists had calculated in worst-case scenarios.
Evidence of this comes from the seismic sensor network in Turkey which measures the amount of ground shaking during quakes – in this case around the East Anatolian Fault which caused the disaster.
Data is preliminary, and could be revised, but some of the highest measurements from some of those sensors exceed the limits for shaking that are assumed in Turkey’s earthquake building design codes.
These typically require buildings to cope with a severity of ground shaking expected to occur once every 475 years. And resist collapsing in a once-every-2,475-year event.
But some sensors recorded peak ground accelerations – a key measure of the earthquake’s force – of well in excess of 7m per second squared.
Turkey-Syria earthquake – latest updates
These values, say experts, appear to exceed the shaking predicted to occur in these areas, even in that rarest, one-in-2,475-year earthquake event.
“Even the very well-designed, very well-executed buildings would have suffered and would have been challenged,” says Prof Yasemin Didem Aktas, a structural engineer at University College London.
“But this doesn’t rule out the building stock we are seeing collapsing was free of defects and problems,” she adds.
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Evidence of that can be seen in cities like Gaziantep – 70km from the quake’s epicentre – that suffered much less severe shaking.
Many large buildings there failed catastrophically, either collapsing into rubble or “pancaking” with floors remaining intact but falling one on top of the other.
Many buildings “pancaked” with floors remaining intact but falling one on top of the other
Risks to cities like Gaziantep were known too. In a publication last year, a team of Turkish hazard experts used existing risk maps to show many neighbourhoods with older, or poorly constructed buildings were a severe risk from an earthquake.
However their modelling exercise assumed a quake 10 times less severe than the one that struck in the early hours of Monday morning.
Another important factor is that there wasn’t just one major earthquake, but two. The first event was followed nine hours later by a magnitude 7.5 aftershock. Some buildings that survived the initial shock collapsed in the second.
Thousands more buildings survived, but are seriously damaged. And this raises a major challenge for authorities dealing with the grim aftermath.
Tens of thousands of survivors are already homeless, but many thousands more may not be able to safely return to homes that may still be standing, but broken beyond repair.
There will be a special programme called Disaster Zone: The Turkey-Syria Earthquake on Sky News on Friday evening at 9.30pm
World
Stock markets slump for second day running after Trump announces tariffs – in worst day for indexes since COVID
Worldwide stock markets have plummeted for the second day running as the fallout from Donald Trump’s global tariffs continues.
While European and Asian markets suffered notable falls, American indexes were the worst hit, with Wall Street closing to a sea of red on Friday following Thursday’s rout – the worst day in US markets since the COVID-19 pandemic.
As it happened: Worst week’s trading in five years
All three of the US’s major indexes were down by more than 5% at market close; The Dow Jones Industrial Average plummeted 5.5%, the S&P 500 was 5.97% lower, and the Nasdaq Composite slipped 5.82%.
The Nasdaq was also 22% below its record-high set in December, which indicates a bear market.
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Ever since the US president announced the tariffs on Wednesday evening, analysts estimate that around $4.9trn (£3.8trn) has been wiped off the value of the global stock market.
Mr Trump has remained unapologetic as the markets struggle, posting in all-caps on Truth Social before the markets closed that “only the weak will fail”.
The UK’s leading stock market, the FTSE 100, also suffered its worst daily drop in more than five years, closing 4.95% down, a level not seen since March 2020.
And the Japanese exchange Nikkei 225 dropped by 2.75% at end of trading, down 20% from its recent peak in July last year.
US indexes had the worst day of trading since the COVID-19 pandemic. Pic: Reuters
Trump holds trade deal talks – reports
It comes as a source told CNN that Mr Trump has been in discussions with Vietnamese, Indian and Israeli representatives to negotiate bespoke trade deals that could alleviate proposed tariffs on those countries before a deadline next week.
The source told the US broadcaster the talks were being held in advance of the reciprocal levies going into effect next week.
Vietnam faced one of the highest reciprocal tariffs announced by the US president this week, with 46% rates on imports. Israeli imports face a 17% rate, and Indian goods will be subject to 26% tariffs.
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Do Trump’s tariffs add up?
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China – hit with 34% tariffs on imported goods – has also announced it will issue its own levy of the same rate on US imports.
Mr Trump said China “played it wrong” and “panicked – the one thing they cannot afford to do” in another all-caps Truth Social post earlier on Friday.
Later, on Air Force One, the US president told reporters that “the beauty” of the tariffs is that they allow for negotiations, referencing talks with Chinese company ByteDance on the sale of social media app TikTok.
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Tariffs: Xi hits back at Trump
He said: “We have a situation with TikTok where China will probably say, ‘We’ll approve a deal, but will you do something on the tariffs?’
“The tariffs give us great power to negotiate. They always have.”
World
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South Korea’s constitutional court has confirmed the dismissal of President Yoon Suk Yeol, who was impeached in December after declaring martial law.
His decision to send troops onto the streets led to the country’s worst political crisis in decades.
The court ruled to uphold the impeachment saying the conservative leader “violated his duty as commander-in-chief by mobilising troops” when he declared martial law.
The president was also said to have taken actions “beyond the powers provided in the constitution”.
Demonstrators stayed overnight near the constitutional court. Pic: AP
Supporters and opponents of the president gathered in their thousands in central Seoul as they awaited the ruling.
The 64-year-old shocked MPs, the public and international allies in early December when he declared martial law, meaning all existing laws regarding civilians were suspended in place of military law.
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The court was under heavy police security guard ahead of the announcement. Pic: AP
After suddenly declaring martial law, Mr Yoon sent hundreds of soldiers and police officers to the National Assembly.
He has argued that he sought to maintain order, but some senior military and police officers sent there have told hearings and investigators that Mr Yoon ordered them to drag out politicians to prevent an assembly vote on his decree.
His presidential powers were suspended when the opposition-dominated assembly voted to impeach him on 14 December, accusing him of rebellion.
The unanimous verdict to uphold parliament’s impeachment and remove Mr Yoon from office required the support of at least six of the court’s eight justices.
South Korea must hold a national election within two months to find a new leader.
Lee Jae-myung, leader of the main liberal opposition Democratic Party, is the early favourite to become the country’s next president, according to surveys.
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