Beirut: The violent earthquake that struck southern Turkey and northern Syria at dawn on 6 February, and the strong aftershock that followed hours later, represent two of the 70 most severe tremors that the region has witnessed since the beginning of the 20th century.
Turkey and its surrounding areas are one of the most seismically active parts of the globe. There are two main faults, the Eastern Anatolian Fault of about 500-530 kilometres, and the Northern Anatolian Fault of about 1,350-1,500 kilometres.
The last two earthquakes occurred in the Eastern Anatolian Fault and left thousands of people dead and tens of thousands injured in both countries, reaching 7.8 and 7.5 on the Richter scale of magnitude.
The biggest earthquake beforehand struck the north of Turkey in 1999 along the Northern Anatolian Fault, with a magnitude of 7.6. It killed 17,000 people.
What causes an earthquake?
These disasters are caused by a build-up of pressure over long periods of time in the Earth’s crust, or lithosphere, which is released suddenly and without clear warning signs, often resulting in devastating and tragic consequences .
The lithosphere consists of seven primary plates and many secondary plates. Under pressure from the heat of the planet’s interior, these plates converge, diverge, and run against each other, accumulating vast pressure over long periods that explodes in waves of energy sent in just moments across large areas.
The surface of our planet is made up of seven tectonic plates, a term rooted in its literal ‘structural’ meaning. The names of the plates — African, Antarctic, Eurasian, Indo-Australian, North American, Pacific, and South American — are related to the parts of the globe where they are located.
Fault lines, like the ones in Turkey and Syria, separate the primary and secondary plates.
Other associated causes
As well as unavoidable natural earthquakes in such areas, some are caused by human activity, such as tunnelling, damming, and projects like geothermal heat extraction and water-fracking to get shale oil and gas.
Many earthquakes are also associated with volcanic activity. But these types are usually less intense than tectonic earthquakes and don’t reach as far. When volcanoes release lava — molten rocks located at great depths where temperatures are very high — these eruptions can start seismic tremors.
There is also a type of earthquake caused by the sinking of the ground due to the erosion of limestone rocks or the collapse of mines.
Seismic pressure around Turkey is exerted as the Arabian Plate slowly moves northward, colliding with the Eurasian Plate, with the country located at the southern edge of the second plate.
As Michael Steckler of Columbia University’s Lamont-Doherty Earth Observatory told the National Public Radio (NPR): “Arabia has slowly been moving north and has been colliding with Turkey, and Turkey is moving out of the way to the west.”