Explainer: Why Turkey and Syria’s calamitous earthquakes were decades in the making

East Anatolian fault zone has been relatively quiet over the past century but has caused several devastating earthquakes in the more distant past

The devastating earthquakes that struck Turkey and neighbouring Syria with tragic force were centred on one of the world’s most seismically active – and politically turbulent – regions.

Strain accumulated over decades as Earth’s slow-moving tectonic plates pushed against one another was released in a few seconds, causing violent vibrations as rock masses suddenly overcame friction and snapped past each other.

Such seismic stresses build up in the region of Turkey because the Arabian plate is pushing the Anatolian plate westward at a rate of about 2cm per year, according to David Rothery, a professor of geosciences at the Open University in the UK.

Joanna Faure Walker, head of University College London’s Institute for Risk and Disaster Reduction, said: “Turkey has experienced the deadliest earthquake worldwide four times in the last 50 years – in 2020, 1999, 1983 and 1975.”


Monday’s first earthquake, which hit in the early hours with a magnitude of 7.8, originated at the south-western end of the East Anatolian fault near its junction with the Dead Sea fault system. The quake was all the more devastating because it took place at a relatively shallow depth of 18km.

The second big quake, only slightly less powerful at magnitude 7.5, followed nine hours later about 100km north-east of the original tremor, at a depth of just 10km. There were also dozens of other smaller quakes, or aftershocks.

“The two events are almost certainly connected,” said Mark Allen, head of the earth science department at Durham University in the UK. “Releasing the stress on one fault zone can load up the stress on another, where it then dissipated in another quake.”

The East Anatolian fault zone, which was responsible for Monday’s events, has been relatively quiet over the past century but has caused several devastating earthquakes in the more distant past.

A historical parallel was an 1822 earthquake in the same area “which completely ruined many towns with heavy casualties”, said Roger Musson, research associate at the British Geological Survey. “In Aleppo alone about 7,000 were said to have been killed... The 1822 earthquake also had many aftershocks continuing into June the following year.”

Catherine Mottram, senior lecturer in structural geology and tectonics at the University of Portsmouth, said southern Turkey was “a very similar geological setting to the San Andreas fault in North America”.

The North Anatolian fault running east-west along Turkey’s Black Sea coast has been much more active in recent times than its East Anatolian counterpart, causing several catastrophes including the magnitude 7.6 Izmit earthquake in 1999 that killed about 18,000 people.

But the two faultlines were sufficiently far apart to make it unlikely that even severe quakes in one would trigger activity in the other, said Allen of Durham University.

Mottram said: “Geophysicists will be able to reconstruct exactly where movement occurred along the fault by reconstructing data collected by seismometers in the region, so more information should come out in the coming days and weeks about exactly what happened.”

Social scientists will be examining the aftermath too. Although many countries rushed to offer co-operation and aid to Turkey and Syria in the immediate aftermath of the quakes, Ilan Kelman, professor of disasters and health at University College London was not optimistic.

His research on “disaster diplomacy” suggested that natural disasters did not create peace.

“Aside from the logistical challenges of humanitarian aid amid places of violence, experience demonstrates that, sadly, previous enmity tends to supersede saving lives and stopping war over the long term,” Kelman said.

Syria has been devastated by a civil war that erupted in 2011 after the Assad regime brutally put down a popular uprising.

Freezing weather

There had already been warnings in recent weeks that a snowstorm across Syria and parts of Turkey had left millions of displaced people at risk of freezing to death.

The NGO International Blue Crescent Relief and Development Foundation said that “heavy snow in the entire region including heavy rain since yesterday has made the lives of the people who abandoned their houses very difficult to survive”. Meanwhile, those who have been trapped under rubble must be reached more quickly if they are to be saved.

Many buildings in the affected region were already vulnerable to collapse. Even in Istanbul, which was unaffected this time, concerns over unregulated development and ageing building stock prompted warnings in 2020 that a major earthquake could leave 10% of the city’s 15m residents homeless.

Most of the buildings which have fallen appear to have been constructed pre-2000, when new regulations in response to the 1999 quake kicked in. In a 2020 piece for catastrophe modelling firm Temblor, Istanbul-based seismologist Haluk Eyidoğan warned that in the south-east of Turkey, “stone masonry and adobe masonry structures in rural areas are weak, and the so-called reinforced concrete carcass multi-storey buildings are demolished in cities”.

The same or worse is true in the affected region of Syria, ground down by the damage inflicted by years of civil war and with many already displaced.

With the earthquake coming against a backdrop of freezing weather, civil war, rocketing prices and fuel shortages, as well as the region’s first cholera outbreak in a decade, the International Rescue Committee has called this “a crisis within multiple crises”, particularly for displaced people.

With hundreds of thousands of refugees on the Syrian side of the border, volunteer rescue NGO the White Helmets said that the region was in “a state of catastrophe”. – Copyright The Financial Times Limited 2023. Additional reporting: Guardian