The catastrophic earthquake that has killed thousands across Turkey and Syria has led to the earth moving three metres in its wake, an expert has said.
The 7.8 magnitude earthquake struck a large area of southern Turkey and part of northern Syria in the early hours of Monday morning (6 February).
Officials have said that more than 4,300 people have died across the two countries, with the Turkish Emergency and Disaster Management Organization (AFAD) confirming there have been 2,291 fatalities in Turkey, along with 15,834 people sustaining injuries in the disaster.
There has also been widespread destruction to homes, buildings and roads, while an Italian seismology expert said the ground itself has moved significantly after the deadly quake.
Professor Carlo Doglioni, president of the Italian National Institute of Geophysics and Volcanology, told Italian newspaper Corriere Della Sera: “What we call the Arabian plate moved about 3 meters along the northeast-southwest direction relative to the Anatolian plate.
“We are talking about a structure in the border region between this world, that of the Arabian plate and that of the Anatolian plate.”
The area sits on several fault lines, meaning it is frequently struck by earthquakes.
According to the US Geological Survey, this week’s was centred about 33 kilometres from the Turkish city of Gaziantep, in the region of Anatolia.
Doglioni added: “We are talking about continuous movement, the plane of the fault is very inclined and during the event we observe a horizontal displacement of the two sides of the fault. The two fins moved relative to each other.
“In other words: it is as if Turkey had moved in relation to the Arabian plate to the southwest.”
Authorities have urged people to stay off the roads, with mosques in the area opened up to offer shelter to those who cannot return to their homes but who need to get out of the cold.
‘The faults that slipped yesterday in Turkey are strike-slip faults that involve mainly horizontal displacements, and so the overall offsets in the region of 3 to 6 metres proposed here are perfectly reasonable.
‘Horizontal offsets of this kind can lead to the severing of major subsurface and surface infrastructure, including water mains, electricity cables, gas pipelines and tunnels.
‘There may also be surface ruptures developed where the faults break through to the surface – these can offset roads, rivers and other features – including built structures. ‘All this is in addition to the damage caused by shaking, liquefaction of soft sediment in valleys/basins and landslides.’
Catastrophic earthquakes are caused when two tectonic plates that are sliding in opposite directions stick and then slip suddenly.
They are composed of Earth’s crust and the uppermost portion of the mantle, while below is the asthenosphere, the warm, viscous conveyor belt of rock on which tectonic plates ride.
They do not all move in the same direction and often clash, which builds up a huge amount of pressure between the two plates. Eventually, this pressure causes one plate to jolt either under or over the other.
This releases a huge amount of energy, creating tremors and destruction to any property or infrastructure nearby. Severe earthquakes normally occur over fault lines where tectonic plates meet, but minor tremors – which still register on the Richter sale – can happen in the middle of these plates.
Turkey is close to the intersection of three tectonic plates, meaning it is prone to earthquakes. Dr Anastasios Sextos, a professor of earthquake engineering at the University of Bristol, said: ‘The area of Aleppo and Gazientep have experienced a series of historically devastating earthquakes and an event of similar magnitude occurred about two centuries ago.’
The majority of Turkey’s landmass sits on the Anatolian Plate, which is being squeezed between three other large plates.
North of the plate is the Eurasian Plate, south is the African Plate and to the east lies the Arabian Plate. These create two large faultlines – the East Anatolian and North Anatolian – which are both prone to seismic activity.
This is because the Arabian plate pushes northwards into the Eurasian plate, squeezing the Anatolian Plate westwards towards the Aegean Sea.
Monday’s earthquakes occurred on the southwest end of the 434 mile-long (699 km) East Anatolian faultline.
The first 7.8-magnitude quake was at a depth of about 11 miles (18 km), while the second occurred nine hours later at a depth of six miles (10 km) and a 7.5-magnitude.
Dr Joanna Faure Walker, professor of earthquake geology and disaster risk reduction at University College London (UCL), said that these were both ‘strike-slip’ earthquakes.
This is where two blocks of land move horizontally along a fault plane as a result of a build-up of stress from horizontal compression. ‘Strike-slip faults have medium strength, so can host earthquakes up to magnitude 7 or 8.
‘The magnitude is dependent on the slip and length of fault that ruptured.
‘So for a fault system that is 690 kilometres long in total, such large magnitude earthquakes are possible.’
The East Anatolian has a slip rate of between 0.2 and 0.4 inches (6 and 10 mm) a year near eastern Turkey.
However, data shared by meteorologist Matthew Cappucci, from MyRadar Weather, shows that this week’s quakes have caused the Anatolian Plate to slide by up to 10 feet (three metres).
Dr Doglioni added that more data from the European Sapce Agency’s Sentinel and ASI CosmoSkymed satellites would provide more information in the next few days.
According to Dr David Rothery, a geoscientist at the Open University, Turkey moves about 0.8 inches (two centimetres) west per year along the East Anatolian fault.
He said: ‘Because of friction along fault lines, the motion is not smooth.
‘Instead strain builds up locally over years or decades until the accumulated stress is strong enough to overcome resistance and rock masses snap past each other in a sudden jerk.
‘In this case, the violence of the shaking at the surface has been strong enough to make buildings collapse, which is probably how most lives have been lost. There may have been landslides too in hilly terrain.’