A strong earthquake hit Turkey and Syria Monday. It was reportedly the strongest quake since 1939 and killed thousands.

Turkey-Syria Earthquake Explained

Seismologist Susan Hough of the U.S. Geological Survey spoke with Science News about the catastrophe that hit the two countries in the Middle East early morning Monday. Hough, who is based in Pasadena, California, said it was too strong for a strike-slip fault.

Hough told the outlet that a quake with a magnitude close to 8 is not common on strike-slip faults because they happen on land and tends to be shallow. However, there can also be severe shaking.

The quake occurred on the East Anatolian Fault, which is a strike-slip fault. It's a result of stress and slip when tectonic plates rub one another. Strike-slip faults produce shallow earthquakes, NBC News reported.

Harold Tobin, the director of the Pacific Northwest Seismic Network and a professor at the University of Washington Department of Earth and Space Sciences, said what happened was a long earthquake, meaning the energy traveled at a great distance along a fault line. The tremor likely destabilized another fault line.

The casualties from the earthquake have already reached 11, 200, BBC reported. According to Turkish officials, 8,574 people died in the country. Meanwhile, it's difficult to get an exact figure from Syria. However, the confirmed deaths were already at 2, 622.

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Why Are The Aftershocks So Strong?

Following the shallow but destructive earthquake, many aftershocks have been recorded. They also noticed that the aftershocks were fairly strong.

According to Hough, as with many other things, there are average expectations and possibilities. The largest aftershocks are, on average, one unit smaller than the main shock. However, that is just an average; the largest aftershock can vary greatly for each main shock.

People also noted the distance [between the main earthquake and some aftershocks that occurred over a hundred kilometers away]. Aftershock is an imprecise term. 

She added that seismologists do not always agree on the definition of aftershocks. The fault that caused the main shock is 200 kilometers long, which will alter the stress in a number of regions. 

It reduces stress in most areas but increases it in others. Thus, aftershocks can occur along the fault and some distance away. It is somewhat uncommon but not unheard of.

Destruction in Turkey Following The Shallow Earthquake Explained

The videos taken after the earthquake hit Turkey were devastating. A lot of buildings collapsed next to each other. According to USGS the affected areas were vulnerable because the buildings were not constructed with concrete, so they did not withstand the strong tremor and prolonged shaking.

Tobin added that the buildings were not designed with modern seismic standards. That's what happened to substandard structures, according to him.

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