Tens of thousands of people have been killed and scores more injured by a huge earthquake which struck south-eastern Turkey, near the Syrian border, in the early hours of Monday morning.
The earthquake, which hit near the town of Gaziantep, was closely followed by numerous aftershocks – including one quake which was almost as large as the first.
On February 6, 2023, a catastrophic 7.8 magnitude earthquake struck southern Turkey near the Syrian border. This was quickly followed by powerful aftershocks including another massive 7.5 magnitude tremor. The devastating earthquakes collapsed thousands of buildings and killed over 41000 people in Turkey and Syria, making it the deadliest earthquake worldwide in over a decade. But what caused this disaster and why was this region hit so hard?
Turkey sits in one of the most seismically active zones on Earth. The country straddles several major fault lines between the clashing tectonic plates that make up Earth’s crust. Understanding the tectonic forces and geography that produced this earthquake provides critical insights for assessing future seismic hazards in the region.
The Clash of Tectonic Plates
The earth is composed of about a dozen major rigid blocks of crust called tectonic plates that are slowly colliding, sliding past, or pulling apart from each other. Turkey lies on the Anatolian Plate, which is squeezed between the massive Eurasian Arabian and African Plates.
The recent earthquakes occurred because of the boundary between two of these tectonic plates
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The Anatolian Plate: This plate makes up most of modern-day Turkey as it extends eastward towards central Asia.
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The Arabian Plate: This plate comprises the Arabian Peninsula and dives under the Anatolian Plate as it moves northward.
As these two enormous slabs of Earth’s crust grind past each other in opposite directions, they accumulate stress at their boundary. The recent earthquakes released some of this pent-up energy as the plates suddenly jerked into new positions, unleashing devastating seismic waves.
Why This Segment of the Fault Line?
The earthquake occurred along the East Anatolian Fault Line, which marks the boundary between the Anatolian and Arabian plates across southeastern Turkey. Specifically, the initial 7.8 quake ruptured a 150 mile segment of this fault extending from near the city of Gaziantep towards the Syria-Turkey border.
This section of the fault line was primed for a major earthquake because stress had been building up there for centuries with no release. Historical records show the last quake of comparable magnitude along this segment was over 200 years ago, in 1822.
The east-west orientated East Anatolian Fault Line is a “strike-slip” fault. This means the Arabian and Anatolian plates predominantly slide horizontally past each other. This lateral motion along the jagged fault creates intense seismic shaking at close range when finally unleashed.
A Zone of Seismic Danger
The tectonics that produced this event make Turkey one of Earth’s most earthquake-prone regions:
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Turkey has experienced 17 magnitude 7+ earthquakes since 1900.
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Over 90% of Turkey lies within an active earthquake zone.
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The Anatolian Plate is being squeezed westward as the Arabian Plate moves north.
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Major fault lines slice through densely populated cities in Turkey.
This geology means Turkey will always face a high seismic risk. Since the East Anatolian Fault continues east past this recent epicenter, experts warn sections further along the fault could also see large quakes in the near future as stress redistributes. This makes preparedness and strict building codes paramount across Turkey to limit future quake damage.
Could It Happen Elsewhere?
Similar forces are at play in other earthquake-prone spots globally. The tectonic situation in Turkey mirrors regions such as:
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The San Andreas Fault in California where the Pacific and North American plates grind past each other.
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The Alpide Belt extending through Greece, Italy, and the Himalayas marked by collisions between multiple plates.
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The Ring of Fire around the Pacific Ocean, an area where most of Earth’s quakes occur as plates collide.
Understanding the tectonic forces that unleashed Turkey’s earthquake helps assess seismic hazards elsewhere. While the particular alignment of plates is unique to each region, the dynamics that produced this quake also lurk beneath other hazardous fault lines worldwide.
The tectonic forces that shook Turkey are ultimately what make our planet livable. Plate motion shapes Earth’s surface and helps drive vital processes like nutrient cycling. But occasionally, the crashing of these plates also unleashes disaster for the communities caught at their boundaries. Assessing seismic hazards relies on mapping the planet’s complex web of fault lines and preparing societies for when the earth inevitably moves once more.
What caused the earthquake?
The Earths crust is made up of separate bits, called plates, that nestle alongside each other.
These plates often try to move but are prevented by the friction of rubbing up against an adjoining one. But sometimes the pressure builds until one plate suddenly jerks across, causing the surface to move.
In this case it was the Arabian plate moving northwards and grinding against the Anatolian plate.
Friction from the plates has been responsible for very damaging earthquakes in the past.
On 13 August 1822 it caused an earthquake registering 7.4 in magnitude, significantly less than the 7.8 magnitude recorded on Monday.
Even so, the 19th Century earthquake resulted in immense damage to towns in the area, with 7,000 deaths recorded in the city of Aleppo alone. Damaging aftershocks continued for nearly a year.
There have already been several aftershocks following the current earthquake and scientists are expecting it to follow the same trend as the previous big one in the region.
Why was it so deadly?
The first earthquake was big – it registered as 7.8, classified as “major” on the official magnitude scale. It broke along about 100km (62 miles) of fault line, causing serious damage to buildings near the fault.
Prof Joanna Faure Walker, head of the Institute for Risk and Disaster Reduction at University College London, said: “Of the deadliest earthquakes in any given year, only two in the last 10 years have been of equivalent magnitude, and four in the previous 10 years.”
But it is not only the power of the tremor that causes devastation.
This incident occurred in the early hours of the morning, when people were inside and sleeping.
The sturdiness of the buildings is also a factor.
Dr Carmen Solana, reader in volcanology and risk communication at the University of Portsmouth, says: “The resistant infrastructure is unfortunately patchy in South Turkey and especially Syria, so saving lives now mostly relies on response. The next 24 hours are crucial to find survivors. After 48 hours the number of survivors decreases enormously.”
This was a region where there had not been a major earthquake for more than 200 years or any warning signs, so the level of preparedness would be less than for a region which was more used to dealing with tremors.
The Science Behind the Massive Turkey-Syria Earthquakes | WSJ
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