José Morales
Professor of Earth Physics at the Andalusian Institute of Geophysics and the University of Granada
The earthquake had a magnitude of Mw=7.7-7.8. It occurred on what is known as the East Anatolian Fault (EAF); the reports I have seen indicate this origin. This fault and its segments are about 700 kilometres long; it is a major fault that has seen destructive earthquakes in the past. This fault accommodates the deformation that occurs between the Arabian and Eurasian plate as a result of the northward movement of the Arabian plate. The other major fault in Turkey is the North Anatolian Fault (NAF) which was also responsible for large earthquakes, such as the 1999 Izmit earthquake of Mw=7.4. Today's earthquake is bigger and is one of the largest ever experienced in that region (Turkey/Syria).
As far as the damage is concerned, I can’t say much yet, but the number of victims will undoubtedly be high. We can see buildings completely collapsed. There, as in Izmit, the vulnerability of the buildings and their seismic resistance is crucial to the damage.
[About the second earthquake] This second earthquake is further north and must have been triggered by the first one. The first data indicate that it is a different structure than the East Anatolian Fault. Now the investigation begins to see the connections between the two.