When a huge earthquake struck south-eastern Turkey and neighbouring Syria at 4.17am local time on Monday, it flattened buildings and killed thousands of people across the two countries.
The 7.8 magnitude quake is the worst to hit Turkey since 1939, when an earthquake in the east of the country killed around 33,000 people.
The tremors from Monday’s quake were felt as far away as Egypt, Lebanon and Israel. A powerful aftershock of magnitude 7.5 followed at 1.24pm.
The quakes affected an exceptionally large area, causing shaking and destruction across a region that is around 12 times the size of Belgium.
Size and scale
The epicentre of the main earthquake was at the south-western end of the East Anatolian fault, near its junction with the Dead Sea fault system. The quake’s impact on the surface was compounded by its relatively shallow depth of 18km. The aftershock hit about 100km farther north nine hours later at an even shallower depth of just 10km.
The low depths of the earthquakes added to their impact on populations hundreds of kilometres away in all directions because shaking intensity is higher the closer an earthquake is to the surface. The US Geological Survey estimated that more than 21mn people experienced a shake intensity of “strong” or above.
The worst affected areas in Turkey are the provinces of Kahramanmaraş, Hatay, Gaziantep and Adıyaman. In Syria, the quakes hit the provinces of Idlib and Aleppo as well as the coastal regions of Latakia and Tartus.
The East Anatolian fault responsible for Monday’s disaster has been relatively quiet in recent decades, which explains in part the tremendous energy released by this week’s earthquakes.
Global and regional context
Significant earthquakes have struck other countries this year, including Indonesia, Vanuatu and Argentina, but Turkey and Syria’s 7.8 quake is the largest by magnitude globally so far.
The Richter scale used to measure the strength of earthquakes is based on a log scale, which means that earthquakes with similar-sounding magnitudes are in fact very different in size.
The TNT equivalent, a linear scale based on the energy released from the equivalent amount of TNT explosive, of the 7.8 magnitude quake in Turkey and Syria is around 7.5mn tons, compared with estimates of 3.8mn tons for Indonesia’s 7.6 magnitude quake and 239,000 tons for Argentina’s 6.8 magnitude quake.
Earthquakes are common in and around Turkey and Syria, but Monday’s 7.8 quake is the largest in the region so far this century.
Monday’s natural disaster struck cities and towns where many buildings are vulnerable to shocks, which experts said was because of low-quality construction and a lack of earthquake resilience.
The earthquakes have led to a devastating death toll in Turkey and Syria, which is expected to rise.
By Thursday morning, Turkey had confirmed 14,014 people had been killed in the earthquakes with thousands more injured. Syrian government and civil defence officials have confirmed more than 2,950 deaths.
Rescue teams are working through the night to pull survivors from the rubble across southern Turkey and northern Syria. But freezing weather, snow and damaged infrastructure are making it challenging to transport aid, personnel and heavy machinery.