On the Ground in Post-Quake Türkiye
On March 25, Senior Structural Project Manager Rebecca Hix Collins headed to Türkiye to survey damage caused by the 7.8 and 7.5 magnitude earthquakes that struck the country.
The trip was funded by the American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI) and coordinated with an international team organized by the American Concrete Institute (ACI) Disaster Reconnaissance Committee. The group represented countries around the world (from local Türkiye to New Zealand, Lebanon, Mexico, and the U.S.), and other organizations including the National Institute of Standards and Technology, as well as Turkish structural engineering faculty and university students. The group spent 10 days investigating the damage along the East Anatolian Fault.
In Rebecca’s words, landing on the ground in Türkiye felt a bit surreal. “Everything happens fast in an emergency response. One minute you’re scrambling for logistics and visas, packing a bag, and researching how to say basic phrases in a new language. The next you’re standing in the aftermath, witnessing firsthand the destruction an earthquake can create.”
Quick Facts About the Kahramanmaraş Earthquake Sequence
- Türkiye is located in one of the most seismically active regions in the world. Nearly 20 earthquakes of magnitude greater than 7.0, and 200 that are greater than 6.0, have struck Türkiye since 1900. The country receives one major earthquake about every five years.
- A destructive earthquake series struck Türkiye on February 6, 2023. The epicenter was estimated to be near the city of Kahramanmaraş, though the impacts covered vast areas of southwest and central Türkiye.
- A complex fault rupture caused a sequence of shallow earthquakes and numerous aftershocks. The series included two primary earthquakes. The first was a 7.8-magnitude earthquake. Then, nine hours later and 60 miles north, a second 7.5-magnitude earthquake was triggered. In total, the fault rupture represented about 370 miles.
- The peak ground velocity values recorded by nearby stations were 3 to 4 times greater than the predicted values given by the Türkiye Building Earthquake Code.
- The earthquakes and their aftershocks caused widespread devastation. The total number of fatalities exceeded 50,000 and more than 200,000 buildings collapsed or were heavily damaged.
- It is estimated that more than 1.5 million people were left homeless.
Clearly, the damage imparted by two very large earthquakes (much larger than new buildings were even designed for) combined with many aftershocks, was devastating. The damage was also severe due to older buildings (not designed to current standards), poor construction (lack of special inspections, poor concrete consolidation, etc.), poor soil conditions (particularly in lakeside towns), and occasionally, poor design (often built against an outdated code).
Despite the undeniable difficulty of witnessing such a scene firsthand, Rebecca confirms that the experience was a powerful one. “Working with the reconnaissance team was an amazing experience. Everyone brought something different to the table and helped balance the group. And despite our different backgrounds and perspectives, we were united in being there to learn as much as we possibly could. To disseminate what we learned into what we can do in the future. To change things for the better.”
Locals were eager to tell their earthquake stories and share information about the buildings. The Turks were so happy that someone was listening, and that people cared about making an impact and creating change.
Sharing Trip Takeaways in STRUCTURE magazine
While onsite, the team of former strangers supported one another. Turkish team members, who made up about half of the group, provided much-needed cultural context and essential translations. Baki Ozturk of Hacettepe University Ankara was instrumental, even finding English translations of documents and drawings. The entire team was fully committed and invested.
Days started early, as the team drove to the chosen observation area. The bulk of the time was spent on-foot, observing damage (or no damage) and taking measurements, photos, and notes. Lunch was a brief rest with snacks. Then, it was back to home base.
Each evening, a group meeting allowed for sharing and recapping what had been seen that day. While onsite, the team’s objectives were to document the behavior of damaged and undamaged buildings: What was the overall performance? How did they behave? Did similar buildings have different damage? Was there significant damage that a seismic evaluation performed per U.S. standards would have missed? Do we need to alter U.S. codes based on what was observed? The team was also interested in the behavior of nonstructural damage (mechanical units, elevators, electrical equipment, etc.) and how it impacted the ability to reoccupy a building, especially hospitals, schools, and residences.
The collaboration didn’t end when the team left Türkiye. Far from it. Team members are still in touch, and support one another’s efforts to bring their research and learning to their respective corners of the world. For Rebecca and teammates Egemen Sönmez, Ph.D. of Izmir University of Economics, Türkiye and Reid Zimmerman, P.E., S.E. of KPFF Portland, that meant creating a written piece to share. The trio published, “When the Ground Shook: Post-Disaster Observations of the Kahramanmaraş Türkiye Earthquake Sequence” published in STRUCTURE magazine. A two-part feature, the latest was released this October.
The first article of the two-part series presents a background on regional seismicity, seismic design and practice in Türkiye, and the authors’ observations from the field.
It’s clear the reconnaissance team learned so much, as the piece includes specific impacts and levels of the earthquake, the history of seismic design codes in Türkiye (including the context around pre-2000 buildings), and the team’s experience on the ground.
According to the article, “buildings were chosen based on ease of access and ranged from functional to severely damaged. The team did not study many collapses, especially as debris removal had already begun. Almost all the buildings were concrete-framed, as described above, though occasionally with wood- or steel-framed roofs. The vast majority of buildings observed were built after 2008.”
Much of the article explores Türkiye’s known issues, and how “issues in design, construction, inspection, and enforcement combined to affect the seismic performance of the primarily reinforced concrete buildings in the region.”
The second article of the two-part series presents “observations relevant to structural practice in the U.S.”
It may be tempting to consider us in the U.S. safely distanced from the experience in Türkiye. As the article states, “Given the spatial separation and cultural differences between Türkiye and the United States, it is easy to fall into the mental trap of preemptively concluding that the damage and casualties seen in the Kahramanmaraş Earthquake Sequence are not representative of what may occur in the United States.” But the truth of the matter is, if we were to have an earthquake that was much larger than our design building code (and research on the Cascadia subduction zone earthquake suggests it is very possible), we could expect similar results. Additionally, we have many older buildings (all those 1970s buildings and older!) that were never designed to modern earthquake code standards. These structures are highly vulnerable, but could be retrofitted.
The piece is encouraging to structural engineers and practitioners, stating, “With a better understanding of the devastating effects of the Kahramanmaraş Earthquake Sequence, structural engineers in the U.S. may begin to question the futility of attempting to change the outcome of a similar earthquake in the U.S. However, the authors encourage U.S. practitioners to instead be reminded of structural engineers’ essential role and the immensely meaningful impact we can make.”
While each earthquake and series are unique, there are patterns. By studying these patterns, which were on full display following Türkiye’s earthquake, key considerations for engineers include:
- Structural observation and special inspection
Sure, special inspections get a bad rap. But nothing proved how truly essential they are quite like standing on the ground in Türkiye. Giving these steps the attention they deserve saves lives.
- Seismic isolation
Seismic isolation resulted in limited structural damage and allowed hospitals to get back to operational standards fast.
- Functional recovery of existing buildings
Many people assume that newer residential and office buildings will be occupiable after a major earthquake. But the priority for most “built-to-code” buildings is life-safety. This means that design focuses on the ability to safely get everyone out of the structure, not for re-occupancy. Often, repairs may be needed in order to re-enter safely. This is true of both U.S. and Turkish building codes. There’s a significant disparity between the public’s expectations and the code. In the U.S., there’s a movement to potentially alter the new building code to reduce this gap, called functional recovery. While a good option for new buildings, this change could present significant costs and hurdles for existing building retrofits, which are already difficult to finance. It’s a change that must be approached carefully, because it would be a shame to discourage updates. We know that even if a life-safety retrofit doesn’t consider re-entry, it’s better than having no retrofit at all.
- Post-earthquake inspection and tagging
This potentially simple process could make an incredible difference in post-earthquake safety. By tagging buildings, residents would know whether it’s safe to re-enter or not, resulting in a less chaotic post-event and many lives saved, especially if there are aftershocks.
- Performance expectations around aftershocks
What’s visible to the public eye doesn’t necessarily reflect what’s happening inside. This truth is especially dangerous after an earthquake, when aftershocks often occur. If a building survives an earthquake and shows minor observable damage, people assume it will survive an aftershock. However, this may not be true. The building code does not have specific checks for aftershock design, or what that level of aftershock might be in different areas. More research may be needed to determine the best evaluation and design methods, if this expectation is to be met.
Further insights into each of these key considerations can be found within Part II of the article.
Rebecca's Experience, Sharing at Home
“On a personal level, this journey was difficult.” says Rebecca. “Some buildings were rubble. During some walkthroughs we’d see stray shoes, photographs, and other evidence of lives lost and people displaced. It would be impossible to be unaffected by what we saw. But as an engineer, there was also a wonder that came with seeing these structures up close and observing how they behaved. It was a strange balance to strike: the interest of an engineer with the reality of being human.”
A few things became abundantly clear to Rebecca, due in part to this trip:
- Understanding what happens after an earthquake is important.
- Good design matters.
- And follow-through (to make sure that good design is executed) is essential.
It is universally important to understand what happens after an earthquake. In Türkiye, witnessing the tragedy firsthand, it was easy to see how people are impacted, to imagine “What if this was our family? Our home?” And while it’s impossible to gain the same understanding from afar, it is worth widening one’s perspective. A better, truer understanding of earthquakes – what it’s like to live through one, what the aftermath entails, and their dramatic affects – undoubtedly changes how we design buildings, our perspective on seemingly tedious seismic standards, and how we prepare our own families.
When it comes to designing our buildings, good design is so, so important. “You can put up a building, but the knowledge to make sure it stands and is safe is entirely different,” says Rebecca. “Being in Türkiye gave me a new appreciation for my field. It drove home why I do what I do. Good design saves lives.”
And good design doesn’t end with a drawing. It needs to get built correctly! Seeing firsthand how little things can make a difference changes the way we see structural observations and special Inspections. Instead of cast as burdensome or tedious, they’re revealed as essential and life-saving.
For individual preparedness, Rebecca recommends the Seven Steps to Earthquake Safety. In addition to coordinating earthquake drills around the nation, the organization publishes great resources around creating a disaster supply kit, reducing hazards at home, taking early earthquake safety steps, creating a household emergency plan, and more. Your preparedness can make a difference.