A powerful magnitude-7.8 earthquake struck southern Turkey, near the Syrian border, followed by a magnitude-7.5 quake nine hours later. Thousands of casualties have been reported, with more expected.
By Temblor Editorial Team, (@temblor)
Updated Feb. 9 at 12 p.m. PT. This story will not be updated further.
Shortly after 4 a.m. local time (1:17 UTC) on Feb. 6, a strong magnitude-7.8 earthquake struck southern Turkey, near the Syrian border. Not long after, a magnitude-6.7 aftershock struck near the mainshock. Several hours later, a magnitude-7.5 earthquake also rocked the region. The relatively shallow depth of the mainshock — close to 20 kilometers — resulted in severe shaking over a large area of Turkey and Syria, as well as parts of Lebanon, Israel, and Cyprus. As of Feb. 9, the death toll surpassed 20,000 with many more expected. Aftershocks are ongoing and will continue to shake the region, making the situation on the ground all the more tenuous (for more on aftershock forecasts, see here). Report shaking with the Euro-Med Seismological Centre (EMSC) and the U.S. Geological Survey (USGS).
The mainshock’s earthquake motion was left-lateral (whichever side of the fault you are on, the other side moved to the left). This is consistent with the motion of the East Anatolian Fault, which has a slip rate of between 6 and 10 millimeters per year. Turkey’s other major fault system, the North Anatolian Fault, is right-lateral. Central Turkey is being squeezed westward between these two great faults, caught in a tectonic vice, spilling into the Mediterranean, toward Crete. This happens because Turkey is being pushed northward by the Arabian Plate.
Early “Did You Feel It?” reports suggest that the strongest shaking occurred northeast of the epicenter, near the cities of Adiyman and Malaya. This suggests that the rupture propagated hundreds of kilometers to the northeast.
Thousands of people have already been confirmed dead in Turkey and Syria. Thousands of buildings throughout the region have collapsed and rescuers are searching through rubble for survivors. The USGS’s PAGER system, which estimates fatalities and economic losses from earthquakes, indicates death toll is likely to rise with economic losses in Turkey alone in the billions. The devastation is widespread and only starting to be uncovered.
The epicenter of the Feb. 6 quake was near the city of Gaziantep in Gaziantep province. The province, along with neighboring Kahramanmaras province, is currently housing hundreds of thousands of Syrian refugees. It’s cold and raining or snowing in much of the region, complicating matters for those whose homes have been destroyed or compromised. Authorities are warning residents not to return to damaged housing.
About nine hours after the magnitude-7.8 earthquake struck, a magnitude-7.5 earthquake followed, about 95 kilometers to the northeast. The location “places it within the vicinity” of a triple junction, where three plates converge: the Anatolia, Arabia and Africa plates, according to USGS. It is within the same fault zone as the magnitude-7.8 quake, but preliminary analysis suggests it struck a different fault strand, according to USGS.
As it followed a larger earthquake in the same general region, the magnitude-7.5 event could be considered an aftershock or perhaps a “contingent event,” according to Ross Stein, CEO of Temblor (which publishes Temblor Earth News), who provided an analysis of the event for several news outlets, including BBC News. That means that had the magnitude-7.8 earthquake not occurred, the magnitude-7.5 earthquake would not likely have occurred either, Stein said. That’s because he calculates that the first event promoted the second. Read Stein and colleagues’ preliminary analysis here.
Temblor’s RealtimeRisk model suggests the quake added stress to adjacent parts of the East Anatolian Fault Zone, with particularly strong increases to the northeast of the mainshock. “The imparted stress brings faults closer to failure, and so are likely sites for large aftershocks,” Stein said. See here for more on Coulomb stress transfer, the process by which one seismic event adds stress to another part of the fault or another fault.
One of the reasons quakes like this are so devastating — aside from the massive size and shallow depth, and aside from the fact that it struck in a heavily populated area — is that buildings in the region are not built to withstand large earthquakes. As Haluk Eyidoğan, a professor of seismology at Istanbul Technical University, Turkey, wrote in a previous story for Temblor Earth News: “We are sadly watching how the stone masonry and adobe masonry structures in rural areas are weak, and the so-called reinforced concrete carcass multistory buildings are demolished in cities.”
For more of Temblor Earth News’ previous coverage of seismic events in Turkey, including an assessment of a November 2022 quake in western Turkey, see here.