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This Friday, a strong earthquake of magnitude 7 shook western Turkey, causing the collapse of several buildings, according to the United States Geophysical Institute (USGS) and local media.
The tremor, which felt in Istanbul and Athens, took place in the Aegean Sea, southwest of Smyrna, Turkey’s third largest city, and near the Greek island of Samos, on the anatolian plate OR Turkish dish, encompassing most of the Anatolian peninsula, and therefore Turkey. Until now they count 20 collapsed buildings in Bornova and Bayrakli in Izmir province, and many people are trapped under the rubble.
According to the USGS, the earthquake, which subsequently produced a tsunami, it occurred ten kilometers deep.
Turkey is located in one of the most active seismic zones in the world. In 1999, an earthquake of magnitude 7.4 shook the northwest of the country, causing more than 17 thousand dead, a thousand of them in Istanbul. In 2011, a jolt of 7.1 in the province of Van he killed 600 people. Last January, a 6.7 earthquake left some forty dead in the province of Elazig.
So why, despite being a known seismic zone, an earthquake magnitude 7 left such an amount of damage?
Pablo Salucci, UC geographer and academic at the Universidad San Sebastián, affirms that “first it is necessary to understand that Turkey is in the area of the Anatolian peninsula, crossed transversely for various failures. In this case, the earthquake occurred at a very shallow depth -only 10 km- which explains the magnitude of the damage. That created a disturbance in the sea, and generated a minor tsunami, but tsunami at last ”.
Cristian Farías Vega, geophysicist and director of the Department of Civil Works and Geology of the Catholic University of Temuco, he points out that “the earthquake occurred in a fault that passes under the sea. It was known for its seismic history, but not as active as what we have in Chile. The place where it was generated was closer to the coastal cities, and being shallow it feels very strong, hitting buildings in a very powerful way ”.
“This has to do with very complex socio-political problems that have made the engineering work in Turkey not the best, resulting in what happened today, with buildings on the ground and people trapped. It is a disaster unnaturalHow they are prepared for something like this ”, explains Farías.
For Pablo Salucci, “the affected area has a lot of old building and not built under earthquake resistant standards. On the other hand, there are also modern buildings that are collapsing, which speaks to lack of preparation by local authoritiesconsidering a long history of major earthquakes ”.
“Turkey is not the best example of a country prepared for earthquakes, even though they do have data. The social and economic problems have been more powerful and therefore earthquakes take a backseat. We are seeing the results of these policies now, ”says Cristian Farías Vega.
“And although the tsunami was not very big in height, it has a lot of power. So much so that it takes boats or yachts, as if it were a very strong storm surge. It is not a wave, but it is a sea inlet that catches what it can. The sea is going to have complications for the next few hours and when it leaves we will see a city full of rubble, due to the earthquake and what the tsunami dragged, ”he says.
“The fact that the earthquake was little deep implies that the seismic wave has a short time to dissipate, and therefore arrives with a lot of energy to the surface. In addition, it is an earthquake in a surface fault and it should be remembered that Santiago has its own failure of this type, which is the Ramón’s fault ”, Salucci says.
The San Ramón Falla -also known as Ramón fault-, is located in a sector densely populated, in the south east sector of the capital. It is located 5 km below the surface and crosses the communes of Puente Alto, La Florida, Peñalolén, La Reina, Las Condes and Vitacura, with 25 km in total, although it is believed that at its extremes it could encompass Pirque and Lo Barnechea.
The geographer explains that “all these earthquakes that occur in faults many times are not incorporated in the standards, like the Chilean, that is prepared for coastal earthquakes, far from more inhabited spaces. Generally these earthquakes last a minute, versus three for example of the earthquake in 2010, being less frequent than those of subduction -which occur daily-, and should not reach magnitudes higher than 7.5, according to what we have seen “.
“Still, they consist of movements of short duration, shallow depth and have high ground acceleration. In this sense, as if it were the control of a blender, the speed at which the ground moves in these earthquakes is much faster than in a coastal earthquake. That is the threat ”, dice.
“All further learning will come with the analysis, but most importantly is to be prepared”, Says the expert. “Chile is a very seismically active country and it requires constant preparation. In the Turkish case, this adds to the pandemic scenario, with people in shelters, grouped together, because they change any protocol that is planned.
“We must not ignore this reality, and although sometimes it is annoying to talk about these issues, you have to assume it”, Sentence Salucci.
