German Seismologist: “The Big Istanbul Earthquake May Be Approaching”

Following the 6.2 magnitude earthquake off the coast of Silivri, Istanbul, seismic attention has once again turned to the Marmara Sea. According to Prof. Dr. Marco Bohnhoff of Germany’s GeoForschungsZentrum (GFZ) in Potsdam, the quake may have shifted tectonic stress closer to Istanbul, raising alarms about the possibility of a much larger seismic event.

As debate intensifies over whether this latest tremor is a precursor to the long-feared Istanbul mega-quake, Bohnhoff outlined two potential scenarios in a statement to DW Türkçe.

Two Scenarios: Main Shock or Foreshock?

Prof. Bohnhoff described two plausible outcomes:

1. The 6.2 quake may have been the main shock, with aftershocks expected to gradually decline in intensity.

2. Alternatively, this event could be a foreshock to a much larger earthquake, with a possible magnitude of up to 7.4.

“This could mean the long-anticipated major earthquake in the Marmara region is still ahead of us. But it’s impossible to confirm which scenario is unfolding at this point,” Bohnhoff said.

Stress Transfer Increases Risk Near Istanbul

The key concern, according to Bohnhoff, is that the tectonic stress along the Marmara fault line has shifted toward Istanbul. This redistribution raises the probability of a larger earthquake occurring closer to the city.

However, the timing remains unpredictable. “We can’t yet determine when a potential major quake might strike,” Bohnhoff emphasized.

Aftershocks Expected—but Likely Below Magnitude 5

The German expert also warned that aftershocks could continue for days or even weeks, although their magnitudes are expected to stay below 5. While less destructive, these smaller quakes can still pose localized risks, especially in structurally vulnerable areas.

“Danger Is Not Over”—Warning Remains Since February 6

Prof. Bohnhoff reiterated that the danger has persisted since the February 6 twin earthquakes in southeastern Turkey. Back then, he warned that the redistribution of stress in fault zones could trigger new quakes across the region, particularly in the northeast.

His latest assessment reinforces that seismic risk in Turkey remains high—especially in and around Istanbul, where preparedness for a major quake is now more critical than ever.