Why is the damage so great?

More than 17,000 people died in the powerful tremors, according to a preliminary report from authorities in the two countries.

I’m used to shaking. This is the first time I have seen something like this. We thought it was doomed, a Turkish journalist testified to AFP. The earthquake, whose first tremor reached a magnitude of 7.8, occurred on the morning of Monday, February 6, ravaging southeastern Turkey and northern Syria.

>> Earthquakes in Turkey and Syria: Follow the situation live

The earthquake and its aftershocks have killed more than 17,000 people in the two countries, according to provisional reports released Thursday. The World Health Organization estimates that 23 million people may be affected by tremors. Thousands of buildings collapsed. Rescuers continued to search for survivors under the rubble on Tuesday. Franceinfo explains why the earthquake caused such havoc.

Because it is a region of the world where seismic activity is important

Türkiye lies on the Anatolian tectonic plate. The earthquake occurred at the level of the East Anatolian fault, i.e. at the junction between the Anatolian plate and the Arabian plate, where the plates slide over each other. “Although an earthquake of this magnitude is rare anywhere in the world, such events are generally expected on long strike-slip faults at plate boundaries.”United States Geological Survey exhibits (Contents in English).

Why so intense? “Here What matters is the speed difference. The Arabian Plate moves northeastward a little faster than the Anatolian Plate, leading to an accumulation of forces in this layer.”details the parisian Seismologist Florent Brenguier from the Institute of Earth Sciences in Grenoble. Furthermore, the East Anatolia Fault has not experienced tremors of such magnitude for more than two centuries, meaning “That was able to accumulate a fairly large amount of energy.” In this space, analyzed Roger Musson, a researcher associated with the British Geological Survey, interviewed by AFP.

Because the first tremor was followed by a very strong aftershock

The first tremor, which occurred in the middle of the night, was particularly strong. It reached a magnitude of 7.8 (on a scale with a maximum of 10). An aftershock of magnitude 7.5 occurred at midnight on Monday, just hours after the initial shock. A United States Institute of Geological Studies map shows the first quake was centered near the Turkish city of Ekinozu, about 100 kilometers north.

This event is exceptional, believes seismologist Martin Valle of the Institute of Earth Physics in Paris, in an interview with BFMTV. “It rarely happens in this context where the earthquake itself was already very strong (…) one would have thought that [le premier] Earthquakes, by their magnitude, release all the pressure that has accumulated in the earth.”developed by the researcher.

Apart from this second quake, no fewer than 184 aftershocks have been recorded since the first on Monday. But their levels have decreased.

Because the earthquake occurred close to the surface

The first earthquake started at a shallow depth of about 17.9 kilometers below the surface near the Turkish city of Gaziantep and its two million inhabitants. The second occurred much closer to the surface: 10 kilometers.

“When an earthquake is relatively shallow, the intensity of the shaking is intense.”

American Institute of Geological Studies

on its website

“Most destructive earthquakes occur less than 15-20 km deep in the Earth’s crust”For its part the French Central Seismological Bureau confirms.

Because the infrastructure was not strong enough

According to experts, the earthquake-damaged houses were not strong enough to withstand the tremors. ” inside Overall, the population of the region lives in structures that are highly vulnerable to earthquakes, although there are some resistant structures.”The United States Geological Survey said in its report (in English) About the event.

On a side note, authorities estimate that around 5,000 buildings have collapsed so far. They collapsed “Like Pancakes”British volcanologist Bill McGuire of University College London told AFP. “This occurs when the walls and floors are not sufficiently aligned, each floor collapsing vertically into the one below.”he added.

The number of infrastructure destroyed in Syria is not known, but it could be just as heavy. “I am per Infrastructure protection is unfortunately uneven in southern Turkey and especially in Syria.”AFP explains Carmen Solana, a volcanologist at Britain’s University of Portsmouth.

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