Aftershocks of science: Turkish scientists clash over Istanbul earthquake risk
Collage of photographs of scientists involved in the debate on the earthquake and the abandoned building destroyed in the recent earthquake in Istanbul, Türkiye, April 29, 2025. (Photo collage by Türkiye Today team)
Following the 6.2-magnitude earthquake that struck off the coast of Silivri in the Sea of Marmara on April 23, 2025, Türkiye’s seismic community has become embroiled in a public and heated debate. As aftershocks ripple through the region, so too do opposing scientific opinions on the nature of the fault lines beneath Istanbul—and the likelihood of a devastating earthquake in the near future.
Predictions and provocations: Professor Sener Usumezsoy challenges mainstream views
Among the most vocal figures is Professor Sener Usumezsoy, who had previously predicted a tremor in the region nearly a month before it occurred. In the aftermath, Usumezsoy has reignited controversy by arguing that the North Anatolian Fault does not run beneath the Princes’ Islands (Adalar), and that the fault in Kumburgaz could only produce a maximum earthquake of magnitude 6.5.
Calling large-scale Istanbul earthquake scenarios “scientifically baseless,” Usumezsoy claimed that many of the supposed active faults in the Marmara Sea are vertical faults with no potential to generate catastrophic quakes.
‘The Adalar Fault died 10 million years ago’
Appearing on various news channels in recent days, Usumezsoy declared, “The Adalar Fault is a dead fault—it died 10 million years ago.” He accused other scientists of relying on what he described as outdated and imaginary maps. “For 20 years, they’ve been defending the same fictional map,” he said.
According to Usumezsoy, faults identified in Tekirdag and Silivri are vertical rather than horizontal strike-slip faults. He further claimed that there is no active fault line between the Kumburgaz Trough and Yesilkoy, contradicting widely accepted scientific models.
A divided scientific community
Prominent Turkish scientists Professor Ovgun Ahmet Ercan, Professor Naci Gorur, and Professor Celal Sengor maintain a starkly different stance. All three assert that a magnitude 7+ earthquake in the Marmara region is not just possible—but inevitable.
Reacting to these assertions, Usumezsoy launched a scathing rebuttal: “These claims are all scientific trash,” he said, adding that experts such as Rolando Armijo—who collaborated with Sengor, Gorur, and French geologist Xavier Le Pichon after the 1999 Izmit earthquake—also allegedly dismissed the idea of a so-called “Great Marmara Earthquake.”
‘Let him stay awake—Let Istanbul sleep’
In response to Professor Ercan’s warning that he would “stay awake and monitor developments,” Usumezsoy responded sharply:
“Let him stay awake. Let Istanbul sleep. All these tremors from the past two days are nothing but aftershocks of the 6.2 quake. These people have been repeating the same alarmist statements since 1999, just to gain popularity. I said what I said 26 years ago, and I still stand by it. Unlike them, I’m not shifting positions just to scare the public.”
Professor Ercan: ‘Aftershocks jumped to Istanbul segment’
Professor Ercan, however, posted a serious warning on social media:
“The M6.2 earthquake on the Thrace segment has shifted stress eastward through aftershocks and unexpectedly jumped to the solid Istanbul segment. The M4.6 quake on 20:05 occurred exactly at the epicenter of the M6.7 quake I’ve been anticipating near Kucukcekmece.”
“If upcoming aftershocks continue to align along the Istanbul segment, we may be facing a deeply concerning situation. I will stay alert and monitor closely. If not, our concerns will diminish.”
Professor Okan Tuysuz: ‘Nothing abnormal’
Attempting to calm the public, Professor Okan Tuysuz shared a brief message via social media, “Can we all just relax a bit? We are monitoring the situation—nothing abnormal so far.”
Professor Gorur reaffirms Istanbul risk: ‘At least magnitude 7.2 expected’
Veteran geoscientist Professor Naci Gorur reiterated his long-standing warning about the Kumburgaz Fault following the April 23 earthquake, stating to Hurriyet:
“The 6.2-magnitude quake has increased the probability of a much larger event—at least 7.2—in the region.”
When asked about a video showing him at a construction site, which critics alleged was part of a commercial campaign, Gorur clarified:
“This wasn’t an advertisement. It was a visitor to a site managed by one of my former students. They used seismic isolators in residential construction—a first in Türkiye. I was proud and gave them a pat on the back. We drank tea and answered some questions about earthquakes.”
“These videos were posted to social media, and now bad-faith actors are trying to discredit me. The real problem is those who claim no major earthquake will happen. They are endangering millions of lives.”
While seismologists agree that Türkiye sits on unstable geologic ground, sharp disagreement over the nature, timing and magnitude of future earthquakes in the Marmara region continues to confuse both the scientific community and the public. But Istanbulites, with a population of more than 15 million, expect urban preparedness from academics and government officials instead of such debates.
