The earthquake that killed more than a thousand people this morning in southern Turkey had a magnitude of 7.8. An aftershock of magnitude 6.7 followed at 11 minutes. The quake is the result of shallow shear faults, and the tentative location of the quake places it in close proximity to the junction between the Eurasian, Anatolian, Arabian, and African plates.

“The earthquake occurred in the so-called East Anatolian Fault (EAF). The solutions I’ve seen point to this origin. This fault and its segments are about 700 kilometers long, and it is an important fault that has had devastating historical earthquakes,” he explains. José Morales, Professor of Earth Physics at the Andalusian Institute of Geophysics and the University of Granada It is reported by the Science Media Center. “This fault is adjusting to the deformation that occurs between the Arabian and Eurasian plates as a result of the movement of the Arabian plate to the north. Another major fault in Turkey is the North Anatolian Fault (NAF), which is also the cause of major earthquakes such as the one in Izmit 1999 Mv=7.4. Today’s is larger and is one of the biggest hit in the region,” he adds.

The mechanism and place of the earthquake correspond to an earthquake that occurred in the zone of the East Anatolian fault or in the zone of the transform fault of the Dead Sea. The East Anatolian Fault accommodates Turkey’s westward extrusion into the Aegean Sea.

Map of Turkey with an earthquake according to the US Seismic Alert System.
Map of Turkey with an earthquake according to the US Seismic Alert System.

Although earthquakes are usually represented as single points on a map, they break up planes that have dimensions as seen on the map. “The earthquake pushes a fault 250 km long and about 25 km wide. It looks very good given the aftershocks that build up along this line,” says Aranta Izquierdo, a seismologist with the National Geographic Institute’s National Seismic Network.

The area where the earthquake occurred is seismically active. Since 1970, there have been three earthquakes of magnitude 6 or greater within 250 km of this earthquake. The strongest of these, with a magnitude of 6.7, occurred northeast of the February 6–January 24, 2020 earthquake. All of these earthquakes occurred along or near the East Anatolian Fault.

Despite a relative seismic lull in the epicentral region on February 6, strong and destructive earthquakes have occurred in the past in southern Turkey and northern Syria. Historically, Aleppo in Syria has been devastated several times by major earthquakes, although the exact location and severity of these earthquakes can only be estimated. Aleppo was hit by a magnitude 7.1 earthquake in 1138 and a magnitude 7.0 earthquake in 1822, according to information from the US seismic hazard system.

“When earthquakes do not occur in a seismically hazardous zone for a long time, this is not good, as and when they occur. But as long as there are no earthquakes, stresses accumulate in the plates, which is why they are more powerful, ”explains a seismologist from National seismic network.

Map of Turkey with history of earthquakes and epicenter of today's earthquake.
Map of Turkey with history of earthquakes and epicenter of today’s earthquake.

In this sense, fears about a strong earthquake in Istanbul are known. Twenty years ago, the city of Izmit was hit by an earthquake that killed more than 17,000 people. Since then, the Istanbul authorities have tightened building regulations, but the historic city of Istanbul, with a population of 15 million, is very vulnerable to a major earthquake that will result in a very high death toll.