Turkey and Syria: new victims of the planet's inner turmoil
Plate tectonics have been, are and will remain one of the greatest unknowns in the history of mankind. Astronomers estimate that there are up to one hundred billion planets in the known universe. Although many Earth-sized worlds lie within the so-called habitable zone of their star, the region where it is neither too hot nor too cold for liquid water to potentially exist on the surface, none possess them. While they allow life to flourish and affect the climate, on the other hand, they are the planet's deadliest weapons. Plate tectonics are proof that even if the entire biosphere were to be extinguished, the Earth would still be "alive".
The earth's surface is a jigsaw puzzle of plates the size of continents that push, rub and collide with each other, generating powerful processes that form mountains and transform landscapes. They are also responsible for the planet's geological metabolism - especially the dynamism of its tectonic plates - making it habitable. If the planet were a cold, dead, inert space rock, life as we know it probably could not exist. These processes carry carbon in and out of the planet's interior, regulating the amount of carbon dioxide in the atmosphere, a greenhouse gas.
An earthquake is a shaking or trembling of the Earth due to internal causes. These movements are caused by the collision of tectonic plates, which are fragments of the lithosphere (the outermost layer of the Earth), which move as a rigid block, without internal deformation of the asthenosphere (the layer next to the lithosphere, which lies between 100 and 240 kilometres below the surface). There are a handful of major tectonic plates and dozens of minor ones. Six of the major ones are named after the continent on which they are located.
These include the North American plate, the African plate, the South American plate, the Eurasian plate (which holds most of Asia and Europe), the Australian plate (where the continent of Oceania would be) and the Antarctic plate. The secondary plates are smaller, but no less important in terms of their influence on the structure of the planet. The small Juan de Fuca plate, for example, is responsible for the volcanoes that dot the Pacific Northwest region of the United States. In our case, the Iberian plate is responsible for our geography and is located north of the African Plate and welded to the European Plate. Earthquakes are constantly occurring all over the planet, especially at plate boundaries.
This time, with respect to the earthquake that has affected the border between Turkey and Syria, the movement occurred on the Anatolian plate. The Anatolian plate or Turkish plate is a continental tectonic plate that comprises most of the Anatolian peninsula (Asia Minor) and thus Turkey. The abrupt movements of the plate have triggered two powerful earthquakes that struck within nine hours of each other in southern and central Turkey on Monday. The preliminary location of the earthquake places it in one of the most peculiar areas of the planet where 3 of the 18 existing plates touch each other. The result: one of the most powerful and deadly earthquakes. After 33 hours - at the time of publication of this article - more than 5,000 people have died and more than 20,000 have been injured. The first earthquake occurred west of the city of Gaziantep at 04:17 local time.
Despite the peculiarity of the area, it is, in seismic terms, a "relatively quiet" area. In the last 50 years there have been only three earthquakes of magnitude 6 or higher. All of them occurred in the vicinity of the Anatolian fault. The fact that the region is described as "quiet" does not detract from the fact that there have been major disasters in the past. Aleppo, Syria's capital, has historically been devastated several times by major earthquakes. Although the precise locations and magnitudes of these earthquakes can only be estimated, the Syrian capital was struck by an earthquake of estimated magnitude 7.1 in 1138 and an earthquake of estimated magnitude 7.0 in 1822. Fatality estimates for the 1822 earthquake were between 20,000 and 60,000 people.
The origin of Monday's midnight quake is due to the strangulation of the area as all the plates surrounding the Anatolian peninsula are pressing inwards. When geologists make judgements about the activity of a region, they rely on dozens of parameters including: the horizontal seismic acceleration, the average depth of tectonic movements and the periodicity. If the first factor is taken into account, the region moves an average of 1 centimetre per earthquake. However, Monday's earthquake shifted the Anatolian fault by more than 2 metres for 70 kilometres, leaving seismologists at a crossroads they cannot understand. Regarding the depth, we must first contextualise. The Anatolian fault is one of the shallowest faults, so in this sense it is a factor that favours the origin of large earthquakes.
Finally, the key factor for the analysis of the area: periodicity. Although there was a large earthquake in the area in 2020, it is only an anomaly. The periodicity of the Anatolian fault to experience an earthquake compared to other faults of the same characteristics is up to 10 times less likely. Geologists estimate that an earthquake greater than 6 on the Richter scale with the violence of IX on the Mercalli scale (whose maximum value would be X) occurs every 772-917 years. To put this in context, on the San Andreas fault the periodicity is 200 years or on the Mentawai fault, origin of the strongest known earthquakes, the periodicity is barely close to 100 years.
One lesson learned from the earthquakes in Turkey and Syria is the importance of disseminating knowledge, not only to experts, since increasing resilience also requires raising awareness and empowering each and every one of the actors involved in these processes. As we indicated at the beginning, earthquakes are one of the greatest unknowns to be resolved. Although they have been known for millennia, no one has been able to warn of them or to silence them. Earthquakes are inevitable events, events that show us that the power of nature always has the last word.
