ISTANBUL

Many residential and commercial buildings managed to withstand the twin powerful earthquakes that hit southern Turkiye on Monday, said a seismologist from the US Geological Survey (USGS).

“Bad it was, there were quite a lot of structures that did go through this earthquake without collapsing, and that is testimony to the fact that buildings can be engineered to be safe and it appears, in many cases it appears, that they were,” Susan Hough told Anadolu in an interview, speaking of the first of Monday’s two powerful quakes, the first taking place in the middle of the night, and the second about nine hours later.

On Monday’s powerful earthquakes that resulted in the death of more than 19,300 people, Hough said that from the images of the affected areas, she was struck to see that while clusters of buildings caved in, there were structures around them that remained intact.

Türkiye lies on an active earthquake zone with fault lines all around. Hough, who works in the geological survey's Earthquake Hazards Program, warned that aftershocks will continue, and that a powerful earthquake could strike again in the same area months or even years from now.

Speaking on Zoom about the earthquake, she said that it impacted a much bigger area because of the size of the fault break. Since the earthquake was shallow and there were many people living close to the fault line, many were severely affected.

“An earthquake as large as 7.8 extended (the) fault break 200 kilometers (124 miles), and the closer you are when the break happens, the more severe the shaking,” she explained, using a figure of 7.8 magnitude for Monday’s first quake, while Turkish scientists usually give a magnitude of 7.7.

Valuable data collected from quakes

Hough said that while for the general public, this earthquake appeared to be a once-in-a-century event, in fact it was not unusual or unexpected.

“They (Turkish earthquake professionals) worked on this for a long time. In a geologic sense, we knew that big earthquakes were going to happen on these faults. The hazard maps, if you look at them, show high hazard, right along this fault, right along the North Anatolian fault, so in a geologic sense we knew that an earthquake like this was going to happen.”

She compared Monday’s quakes in Türkiye to the infamous 1906 San Francisco earthquake, saying that it is a similar type of fault, called a strike slip fault.

In the 7.9 magnitude San Francisco earthquake, the fault break was 400 km (249 mi) away from the bustling city, she said. But in the Turkish quake, the fault break was just 200 km (124 mi) away from heavily populated areas.

Türkiye has a very active first class community of earthquake professionals, scientists, and engineers, she said.

On the earthquake monitoring system in Türkiye, Hough said that that the country has invested in monitoring instruments, including those that are designed to stay on scale during large earthquakes. Thanks to these instruments, valuable data on Monday’s quakes have been collected.

"I’ve seen early maps that show a spectacular set of data recorded for this event, how it shook instruments right along the fault, and some distance away," she explained.

She added: "As earthquakes … are infrequent on a human time scale, we don’t have that much data, what is a 7.8, how does it shake the ground.”

The data from Monday’s quakes will present a “spectacular and very important data set for earthquake engineering,” she said, which may be the quakes’ biggest scientific impact.

On quake-resistant structures, Hough said buildings can be constructed that would stand the strongest shaking that earthquakes can generate.

“We have building codes developed, there are international building codes that specify how construction has to be done to make buildings earthquake resilient,” she explained.

“Most building codes are designed to protect life safety so a building might be damaged by an earthquake if it’s properly built to the code, but the idea is that it won't collapse. That the goal is to keep people from being killed.”

Hough says she hopes for a more coordinated global approach toward earthquake monitoring and awareness to help save lives.

“We do have a global seismic network so when an earthquake magnitude 5 occurs anywhere in the world, it’s reported by global instruments and so there’s basic information but… there’s so much more that could be done, to bring people together, to understand hazards.”