The earthquake, the strongest in the region since 1939, killed thousands in Turkey and Syria.
In the early morning of February 6, a devastating earthquake with a magnitude of 7.8 occurred in the south of Turkey, near the border with Syria. After that, there were numerous aftershocks, the strongest of which almost did not match the main earthquake with a magnitude of 7.5. By evening, the death toll in both countries had risen to more than 3,700 and was expected to continue rising, according to Reuters.
Most of Turkey sits on a small tectonic plate that is sandwiched between two slowly colliding giants: the large Eurasian plate to the north and the Arabian plate to the south. When these two plates collide, Turkey is squeezed sideways, like a watermelon seed being torn between two fingers, says seismologist Susan Gough of the US Geological Survey.
The entire country is surrounded by fault zones or lateral faults: the North Anatolian Fault, which runs roughly parallel to the Black Sea, and the East Anatolian Fault near the border with Syria. In this regard, Turkey is very seismically active. Even so, Monday’s earthquake, which struck the East Anatolian Fault, was the region’s strongest since 1939, when a 7.8-magnitude earthquake killed 30,000 people.
Reporters spoke with Gough, who lives in Pasadena, California, about the earthquake, its aftershocks and building codes. The conversation has been edited for length and clarity.
Journalist: You say on Twitter that it was a powerful earthquake for a thrust fault. can you explain
Gaffe : The world has seen bigger earthquakes. Subduction zones generate the strongest earthquakes, up to 9 points. But earthquakes with a magnitude of about 8 points are not a common occurrence for thrust faults. But because they’re on land and tend to be shallow, you can get a big jolt … a tremor near a fault that’s moving.
Journalist: Some aftershocks were very strong, with a magnitude of 7.5 and 6.7. Is this unusual?
Gaffe : As with many things, on average there is what is expected and there is what is possible. On average, the largest aftershocks are a whole unit smaller than the mainshock. But this is only an average value; for any single mainshock, the largest aftershock can have large variability.
Another thing people noted was the distance [між головним поштовхом і деякими афтершоками на відстані понад сто кілометрів]. Aftershock as a term is not accurate. Seismologists have not always understood what an aftershock is. The fault that caused the main shock is 200 kilometers long, and this will change the stress in many areas. It relieves stress for the most part, but increases stress in some areas. So you can get aftershocks along that fault, but also some distance away. It’s a little unusual, but not unheard of.
Reporter : People have been wondering if Monday’s magnitude 3 earthquake near Buffalo, New York, could be related.
Gaffe : A 7.8 magnitude earthquake creates [сейсмічні] waves that you can capture all over the Earth, so it technically destroys every point on Earth. So, it’s not exactly an amazing idea, but it’s statistically extremely unlikely. Maybe if a seismic wave went through a fault that was willing to go in the right direction, it might be possible.
interesting [і абсолютно окрема] the idea is that you can get earthquakes around the perimeter of the Great Lakes [наприклад, біля Буффало], because as the lake level rises and falls, you stress the Earth’s crust, putting weight on one side or the other. This is the source of stress that can cause these fairly small earthquakes.
Journalist : The images that emerge after this deadly disaster are terrifying.
Gaffe : It’s hard to watch. And this emphasizes the importance of building regulations. One of the problems that any place faces is that building codes improve over time and you always have the problem of old structures. It’s really expensive to convert. I expect earthquake engineers to study the damage and that will highlight where the vulnerabilities are [в цьому районі]. We hope that through proper design we can make the architectural environment safe.
