A powerful earthquake struck southern Turkey early Monday morning, causing extensive damage and killing thousands there and in neighboring Syria. Survivors face the bitter cold of winter, blackouts, water outages, and the terror of subsequent aftershocks.
The 7.8-magnitude earthquake struck near Nuruda, not far from the city of Gaziantep, at 4:17 a.m. local time, according to the US Geological Survey. It was also felt in Lebanon, Israel and Cyprus. The quake was followed hours later by a magnitude 7.5 aftershock, followed by a number of smaller aftershocks. (Earthquake magnitudes are logarithmic, so an earthquake of magnitude 7.0 is 10 times more than an earthquake of magnitude 6.0. The former releases 32 times more energy than the latter.)
Monday’s quake made the surface more violent, with the rupture of a relatively shallow fault about 18 kilometers (11 miles) below the surface.according to new york timesThe earthquake destroyed nearly 3,000 buildings in Turkey and killed more than 3,000 people in the country and Syria. The number of casualties is expected to increase due to the high population density in the area and especially the large number of Syrian refugees who often live in makeshift or unsturdy buildings.
To learn more about this region, which is famous for its seismic activity, and why this quake was so damaging, visit Scientific American We spoke with seismologist Ross Stein, CEO of catastrophe modeling firm Temblor.
[An edited transcript of the interview follows.]
Why is Turkey a seismically active region?
Turkey is squeezed by a huge structural vise. The Arabian subcontinent is moving northward, essentially pushing Turkey northward against the fixed borders of Northern Europe. And what happens is that Turkey is pushed westwards, where it flows into the Mediterranean Sea, and is eventually pushed under Crete in a subduction zone, overlooking Japan.
How often do earthquakes of this magnitude and strength occur in Turkey?
they are rare. That’s the short answer. It’s like a once-in-a-century event. In 1939 there was an earthquake of magnitude 7.8. This was the beginning of a series of the most spectacular falling domino earthquakes the world has ever experienced. This ruptured the North Anatolian Fault over his 1,000 kilometers (almost end-to-end) and caused him 12 very large earthquakes in 60 years. It’s a slow-motion car crash, one earthquake triggering one after another. We know that San Andreas and other faults of this sort can do something like that, but this is the clearest and simplest example we know of.
What makes these stronger quakes so rare?
A kind of strange mathematics for earthquakes is that each jump of one magnitude unit reduces the chance of occurrence by a factor of ten. So the larger the size, the less frequent. There is debate about it. Some claim to be able to identify the maximum size of earthquakes that characterize faults. But I doubt the data show that. In 100 years, 20 occurrences of magnitude 7 should result in two occurrences of magnitude 8. Roughly speaking, that’s what we see.
And can they get even bigger? no one knowsThe Arrogance of the Earthquake Community Is to Claim They Can Predict How Big an Earthquake Could Be [on a given fault]. On the East Anatolian Fault [where the recent earthquake occurred]many researchers fixed the maximum magnitude around 7.4.
The quake spanned a fairly long range of about 400 kilometers and was followed by a magnitude 7.5 aftershock. Can you talk about these and other interesting aspects of this earthquake?
One of the things we’re doing, and what Temblor and many other scientists are doing, is trying to calculate how one earthquake changes the collapse conditions around it. . This is called a “coulomb stress trigger”. We did the math last night and sent it to the client. There, we showed that this quake illuminated part of the East Anatolian Fault, further north and south.And this morning it was magnitude 7.5 [ET] Basically, in that blow torch zone. So it was similar to what we’ve seen in domino sequences falling along the North Anatolian Fault. This means it may not be finished. An earthquake is a kind of chain reaction. They communicate by transmitting stress. A single earthquake can reduce the stress in the ruptured part, but transfer the stress to other parts. Aftershocks tell the story. Aftershocks are not limited to the rupture site. They occur in their perimeter over fairly large distances.
Why was this earthquake particularly damaging?
The biggest factor is the quality of the building. It just trumps everything else. Building quality is governed by building codes and their enforcement. Turkey experienced her 1999 terrible Izmit earthquake. [more than 15,000] Therefore, Turkey enacted a modern building code within a few years of the earthquake. So you say Are these buildings more than 20 years old to him, or were they constructed in a way that was not properly reinforced?”
I was there after the 1999 Izmit earthquake. We were visiting the factory. Construct sturdy buildings in reinforced concrete, the standard building material around the world. What you do is: You have rebar – you have these steel bars inside the columns and beams. And you concentrate their strength and density in the corners and joints. . This is because the seismic stress is concentrated there.
So we were inside this failed manufacturing plant, and we could see that there was a large crack in one of these joints – how many rebars were in there? There was a crack so big you could see it. The world would be a safer place if concrete was translucent. This is the problem. It’s too easy to cheat.
I don’t know if it’s a collapsed building. [in the recent quake] I’m not blaming anyone because it’s an old building or a poor building. But this is a global problem, not just Turkey.
Is there anything else you would like us to be aware of regarding the risk of earthquakes?
I think it’s a reminder. I think what has happened in the last five years is that people are going to believe that earthquakes don’t happen anymore and now it’s just floods and wildfires. It’s definitely a California view. It’s like intentional blindness.Been in California for a long time so I can understand that [since a major earthquake]It’s a reminder of what can happen in an environment like San Andreas, where big earthquakes do happen. And the difference between a relatively harmless earthquake and a disaster is how much we build and how much we prepare.
If people want to do one thing (it costs $1), put an international orange whistle on their keychain to ensure their safety in earthquake country. The reason is that even if you are trapped in a building, no one will dig you out unless they know you are alive. You can’t scream for a long time until you’ve used up all the moisture. Also, you can’t hear it far away. With this whistle, you can yell for a really long time.
