More than 2,000 fatalities have so far demanded the heavy earthquake on Monday night in south of Turkey. Experts expect the number to increase significantly again. The shock with a thickness of 7.8 hit a population -rich border region between Turkey and Syria, in the area affected by the earthquake, among other things, the city of Gaziantep with around two million inhabitants. In Syria, the civil war drove around four million refugees into the border region.
First photos and videos from the region show severe damage to buildings. The quake is the strongest in Turkey since the approximately equally strong Erzican earthquake of 1939, and the strongest earthquake ever observed in the border region with Syria. In addition, it took place at a depth of only 18 kilometres, and the shorter the distance to the earth's surface, the stronger the tremors there. In addition, there are unusually violent aftershocks. One of these, which occurred ten hours after the first blow a little further north along the fault, was also stronger than all the historic quakes in the region with a magnitude of 7.5.
The origin of the quake is a long–known boundary between two parts of the Earth's crust - the East Anatolian Fault, one of two major earthquake zones in Turkey. "The earthquake has its origin at the southwest end of the East Anatolian Fault, near the connection to the north-south Dead Sea Transform fault," Roger Musson of the British Geological Survey told the British Science Media Center. There, the Anatolian and the Arabian Plates slide along each other at a speed of five to ten millimeters per year.
Africa's collision with Eurasia is behind the quake
The rocks of the rejection get caught and tension builds up. If it becomes too big, the rock breaks in one place. The break spreads out at the speed of sound and the voltage is released as an earthquake energy. The longer the broken part of the rejection, the more energy the quake releases.
A possible reason for the severity of the quake is therefore the unusually long break zone with around 400 kilometers. Only with a few historical quakes of transform disorders have a long break zone have been observed, writes the seismologist Martin Mai from King Abdullah University of Science and Technology in Saudi Arabia.
In addition, the danger is by no means over after the first shock, as the severe aftershock in the morning shows. The first fracture by no means relieves all the tension in the fault. "There are still aftershocks from today's event," Musson says, "one with a magnitude of 6.7 occurred only eleven minutes after the first quake.«
The East Anatolian rejection is part of that gigantic collision zone between the African record in the south and the Eurasian plate in the north. Various smaller fragments of the earth's crust rubbing together between the collapsing continents. The anatolian plate on which the central Türki lies is one of them, another the Arabic plate that borders them along the East Anatolian rejection. This fault zone runs from the northeastern tip of the Mediterranean towards the northeast and connects two zones in which parts of the earth's crust collide with each other.
At its southern end, the Cyprus Arch extends westwards into the Mediterranean Sea. There, the seabed dives under the Anatolian Plate and lifts Cyprus into the air. At its northern end in Anatolia, the Eastern Anatolian Fault merges into the Zagros collision Zone, which extends to the southeast into Iran, in which the Earth's crust has been piled up into a mighty fold Mountain range by the Arabian Plate pushing to the north.
A gigantic screw clamp
In addition, the fault meets Turkey's second dangerous earthquake zone there: the North Anatolian Fault, which runs in a large arc to the northwest over Istanbul and through the Sea of Marmara. The two major faults are the northern and eastern edges of the Anatolian Plate. They form a triangle pointing to the east, which reveals the underlying cause of the severe earthquakes in the region.
The anatolian plate with Turkey is located in a gigantic geological screw clamp. The huge Eurasian plate lies in the north, from the south the Arabic plate presses as part of Africa. The comparatively small anatolian plate on which the majority of Turkey is located is put into the pliers by these two large fragments of the earth's crust. It evades the pressure by slipping out of this geological screw clamp to the side. And this movement always creates heavy earthquakes in Turkey.
Experts fear that there could be thousands of deaths, because many buildings have collapsed or badly damaged. A heavy quake of the strength 7.6 in 1999 in Izmir, in which around 18,000 people died, had already led to harder building regulations. "In 2004, the Turkish government issued a new law, according to which new buildings have to be built according to modern earthquake-proof standards," explains Joanna Faure Walker, head of the Institute for Risk and Disaster reduction at the University of College London. "After this new event, it will be important to check whether these regulations have been observed in all buildings since then and whether the specifications are sufficient." You also have to check how to better protect older buildings.
First, however, the rescue work is pending - and they have to go quickly. The next 24 hours are crucial to recover survivors, because after about two days the probability drops significantly that the victims still live among the ruins. However, the cold weather, the destruction caused by the previous quake and the persistent danger of severe aftershocks hinder the rescue work. Last but not least, the fights in Syria, which have been going on for years, in which Turkey is also involved, make it difficult to deal with the disaster.
