The 2023 Turkey Earthquakes: “It Felt Like It Would Never Be Over”
Turkey and Syria are reeling after being struck by two enormous earthquakes in quick succession. Both earthquakes occurred along the East Anatolian Fault Zone; between them and their aftershocks, the damage is catastrophic, and the death toll is already in the thousands and rapidly climbing.
The first earthquake, striking near Gaziantep at 4:17 am local time, was measured by the USGS as a M7.8. At first, it wasn’t clear whether this earthquake struck within the East Anatolian Fault Zone (EAFZ) or the Dead Sea Transform fault zone. As of this writing, it appears it was located within the EAFZ.
The second earthquake struck near Ekinözü at 1:24 pm local time, and measured as a M7.5. Though it was 95 kilometers northeast of the initial quake and on a separate fault, it qualifies as an aftershock instead of a stand-alone earthquake. More on that later in this post.
We won’t have a clear picture of precisely which faults were involved, the details of the earthquakes, and the implications for the region going forward for months, possibly longer. Once we have some solid science, I’ll write up a properly detailed post for you. For today, I’ll go over some of the best available science, share some sobering videos, and provide ways you can help people in the affected region.
USGS Earthquakes posted an animation showing the two main quakes and their aftershocks. You can see the faults lighting up, and see clearly that there are two separate faults involved for both of the largest quakes.
GeologyHub has a good initial video, but keep in mind that the specific faults involved haven’t been formally identified and information will undoubtedly change.
Temblor’s Ross Stein gave a quick overview of the earthquakes and the regional tectonics that gave rise to them:
This Temblor article explains the events in more detail.
The mainshock’s earthquake motion was left-lateral (whichever side of the fault you are on, the other side moved to the left). This is consistent with the motion of the East Anatolian Fault, which has a slip rate of between 6 and 10 millimeters per year. Turkey’s other major fault system, the North Anatolian Fault, is right-lateral. Central Turkey is being squeezed westward between these two great faults, caught in a tectonic vice, spilling into the Mediterranean, toward Crete. This happens because Turkey is being pushed northward by the Arabian Plate.
The Washington Post spoke to geologists who added more insight into the tectonic situation:
The Arabian plate is plowing northward at a rate of about 11 millimeters (just under a half-inch) per year, said Stephen Hicks, a seismologist at University College London. Turkey, which sits on the Anatolian plate, is therefore being squeezed westward.
That movement means Turkey has two major faults where earthquakes originate: the 930-mile-long North Anatolian fault and the more than 300-mile-long East Anatolian fault. Many of Turkey’s largest quakes originate on the northern fault, and it has gained the most attention because of the potential for a major quake near the population center of Istanbul.
But this one is thought to have struck along the East Anatolia fault zone — which has been flying a bit under the radar, with no earthquakes greater than magnitude 7 “at least since our seismological monitoring network has been in place — the 1900s,” Hicks said. The lack of recent large earthquakes in the last century along that fault, combined with the northward movement of the Arabian plate, suggest there was pent-up strain in the region, he said.
In an interview with Temblor’s Ross Stein, Scientific American elicited some intriguing and alarming details about the quakes and their potential aftermath:
This earthquake ruptured over a fairly long stretch, about 400 kilometers, and was followed by a magnitude 7.5 aftershock. Can you talk about these and any other interesting aspects of this quake?
So one of the things that we do, that Temblor does and a lot of scientists do, is try to calculate how one earthquake changes the conditions for failure around it. We call this “Coulomb stress triggering.” And we made a calculation last night, which we sent out to our clients, where we showed that this earthquake should light up parts of the East Anatolian Fault, farther to the north and to the south. And we had a magnitude 7.5 early this morning [ET] in, basically, that blowtorch zone. So it was kind of similar to what we saw in the falling-domino sequence along the North Anatolian Fault—which means this may not be over. Earthquakes are in a kind of chain reaction; they converse by the transfer of stress. One earthquake might drop the stress on the section that ruptured, but it transfers it to other sections. Aftershocks tell us that story. Aftershocks don’t just occur where their rupture took place. They occur around it over fairly large distances.
(If you only have time to read one article, that’s the one I recommend. Particularly for the horrifying details about why so many buildings in this region fail.)
The M7.5 was surprisingly large for an aftershock, and occurred on a different fault, so a lot of us early on made the mistake of believing there had been two separate earthquakes in the region. But most seismologists are marking the M7.5 up as an aftershock, and NBC has a clear explanation as to why:
Seismologists said the 7.5-magnitude shake that came after the initial quake qualified as an aftershock, not a separate earthquake, because it met aftershock classifications: It occurred within one fault line of the initial quake, and it was smaller in magnitude.
(That article includes quotes from Dr. Lucy Jones. We’re going to get to know her quite well around here, just as soon as I get round to reading and reviewing her book.)
As to why, aside from sheer magnitude, these earthquakes were so damaging, the USGS has a little something to say about it.
“It’s difficult to watch this tragedy unfold, especially since we’ve known for a long time about how poorly the buildings in the region tend to behave in earthquakes,” said USGS scientist David Wald. “An earthquake this size has the potential to be damaging anywhere in the world, but many structures in this region are particularly vulnerable.”
Earthquakes don’t kill people, so much as not making our buildings resistant to seismic shaking kills people.
Drone footage shows a small slice of the devastation caused when the earth shakes buildings that aren’t prepared to survive it:
And this terrifying video of the moment the second quake hit is going to be horrifically familiar to those who lived through 9/11: people running, and a look back at a cloud of dust from a collapsing video. Definite trigger warning for this one:
The human toll is unimaginable. CNN has a few of the survivors’ stories.
Eyad Kourdi, a CNN producer in Gaziantep, who was staying with his parents when the earthquake struck early Monday, said “it felt like it would never be over.”
The quakes stuck in a region full of refugees from the Syrian civil war. These people were already suffering; now what little they had left is gone. If you can donate money, the Washington Post has a good guide to charities and resources for ensuring the charity you choose is legitimate. I’ve shared the article using a gift link, so you should be able to access it without a subscription.
Doctors Without Borders is always an excellent organization to support. Another excellent choice for supporting victims of this disaster is the Syrian American Medical Society.
Featured image: The wreckage of a collapsed building, Diyarbakır, Turkey. Credit: Mahmut Bozarslan (VOA)
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