How regional fault lines led to such a devastating earthquake in Turkey, Syria

Experts say it is only a matter of time before the region around Turkey and Syria experiences “the big one”.

Tens of thousands died in two cataclysmic earthquakes that struck the region on February 6. First, a 7.8-magnitude earthquake struck Gaziantep in southeastern Turkey on the border with Syria, followed by a 7.5-magnitude tremor nine hours later about 100 miles north of the first, with hundreds of aftershocks in between and beyond.

The tremors destroyed thousands of buildings in the two countries and killed at least 42,000 people.

While individual earthquake activity is difficult to predict, it was never out of the question that a major earthquake would be looming on the horizon in the region, experts told ABC News.

PHOTO: In this March 29, 1964 file photo, cliff-side homes lie in ruins in the Turnagin neighborhood of Anchorage, Alaska. (Bettmann Archive/Getty Images, FILE)

Turkey is at the crossroads of tectonic plate activity

The complex tectonic activity underlying it was essentially what ensured that a devastating powerful earthquake would eventually shake the region, the scientists said.

There are four tectonic plates, massive slabs of rock from the Earth’s lithosphere, that interact in Turkey. The Arabian and African plates are moving north, interacting with the Eurasian plate, which essentially serves as a boundary to the north, Joshua Russell, a professor of seismology at Syracuse University, told ABC News.

“This stress is essentially pushing Turkey westward into the Aegean,” Alexander Stewart, a professor of geology at St. Lawrence University, told ABC News.

PHOTO: Earth’s tectonic plates (ABC News, Statista)

Imagine a banana being squeezed out between the skins, and that’s how turkey is excreted into the Aegean essentially as a result of plate interactions, Stewart said.

What makes Turkey even more vulnerable is that movement from the Anatolian Plate is essentially sliding along fault lines of the North Anatolian Fault Zone, the most seismically active fault zone in the world, Stewart said.

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But what was responsible for the most recent deadly quake was the East Anatolian Fault Zone, which stretches down through Syria. The energy released by the “rock-to-rock sliding” of the plates on the East Anatolian Fault, which is less active than the North Anatolian Fault, is more catastrophic than earthquakes, which release the stress on a more consistent basis, Stewart said.

Although the earthquake was of considerable magnitude, the readings on the seismograph, which measure the amplitude of the waveforms or how much fault is moving, do not tell the full story of the earthquake’s magnitude.

PHOTO: Tectonic Plates and Turkey (ABC News, Middleeasteye)

The earthquake included a fault disruption that extended 300 kilometers, or more than 186 miles, Susan Hough, a seismologist with the US Geological Survey, told ABC News.

“The bigger the fault, the bigger the earthquake,” Russell said, adding that the shallower the earthquake, the more ground motion.

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When the quake happens, it doesn’t tremble all at once. From the epicenter, the fracture is traveling down the fold at about 3 kilometers per second, Hough said. So if it continues 300 kilometers, it’s actually moving for 100 seconds, Hough said.

So in addition to the quake’s very long duration, it’s also affecting a “huge” area, Hough said.

PHOTO: Anchorage’s main thoroughfare is shown on March 29, 1964 after the 1964 earthquake. (Bettmann Archive/Getty Images, FILE)

Stewart estimates that Turkey is in the top 20% of regions in the world that would be devastated by earthquakes.

A 7.3 magnitude earthquake in Fukushima, Japan, in March 2022 killed just four people. The magnitude of the earthquake was not “extraordinary,” but despite Japan being an earthquake-prone region, the country’s economic system is capable of providing and constructing structures that can withstand moderate earthquake magnitudes.

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The same is not true for regions like eastern Turkey and Haiti.

In 1936, the North Anatolian Fault erupted under the Sea of ​​Marmara, also resulting in tens of thousands of deaths. This is when building codes began to be introduced in the country. Another earthquake in 1999 resulted in additional building codes, but these are not enforced, Stewart said.

“It takes a long time to retrofit buildings and it’s expensive,” Russell said.

Could a similar earthquake happen in the US?

The west coast of the continental US and Alaska are also prone to earthquakes, the experts said.

One of the most destructive earthquakes in the US occurred in 1906 when nearly 300 miles of the San Andreas Fault ruptured, resulting in a magnitude 7.9 earthquake that killed at least 3,000 people in the San Francisco Bay Area. In 1933, the Newport-Inglewood Fault in Long Beach, California, caused a magnitude 6.4 earthquake that caused extensive damage and killed up to 120 people.

PHOTO: Destroyed buildings and debris are shown after the 1906 San Francisco earthquake. (Gado via Getty Images, FILE)

The Long Beach earthquake “taught engineers a lot about how much the ground can shake from a magnitude 6.5,” Hough said.

For decades, California has planned its engineering and building codes based on historic seismicity to survive earthquakes of similar magnitude, the experts said. Additionally, single-family homes tend to be more resilient to earthquakes than high-rise apartment buildings, Hough said.

California highways, particularly bridges and overpasses, have also been retrofitted with steel to protect drivers in the event of an earthquake, Hough said.

“In general, overall resilience is better in California than in Turkey,” Hough said.

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Settlements along fault lines often have high population densities because faults tend to be nice places to live, Hough said. There’s usually water, mountains and more rain in the area, and people will congregate around those regions, she said.

This can prove problematic because the closer you are to the moving disturbance, the more you’ll tremble, Hough said.

“You have the settlements right at the top, and then when you have the construction issues, it’s kind of a perfect storm for big damage,” she said.

PHOTO: Rescue workers pull up a car parked over a section of bridge collapsed in an earthquake on October 17, 1989 in San Francisco. (Bettmann Archive/Getty Images, FILE)

However, the largest earthquakes in the US tend to occur in Alaska.

“Nobody lives up there,” so these quakes don’t get publicized as often, Stewart said. However, because these earthquakes are so large, they can create other wave effects like tsunamis, Hough said.

Although the U.S. would not see a similar caliber of deaths as Turkey and Syria, there would be severe economic damage, Stewart said.

“Our efforts in retrofitting and designing to save lives in Japan and North America are very high, but the economic losses are not minimized,” he said.

How regional fault lines led to such a devastating earthquake in Turkey, Syria originally appeared on abcnews.go.com

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