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A 7.8-magnitude earthquake hit southeastern Turkey and parts of Syria in the early hours of Monday, 6 February. The quake was followed by a 7.5-magnitude quake some nine hours later, in addition to dozens of aftershocks.
The death toll has risen to 5,000 in the last 24 hours – and is expected to go up further.
Speaking to Reuters, seismologists said the Turkey-Syria earthquake is likely to be one of the deadliest this decade. In fact, it was so powerful that tremors were felt as far away as Cyprus (456 km away), Lebanon (874 km), Israel (1,381 km), and Egypt (1,411 km).
But why was this earthquake so deadly? And why do aftershocks occur? Read on.
Why Is Turkey a Hotbed of Seismic Activity?
Turkey lies in a seismically active zone. It is located on the Anatolian tectonic plate, which is wedged between the Eurasian and African plates. On the north side, the minor Arabian plate further restricts movement. One fault line, the North Anatolian fault (NAF) line, which is the meeting point between the Eurasian and Anatolian tectonic plates, is known to be "particularly devastating."
The NAF has been responsible for catastrophic earthquakes in the past, too. In 1999, it caused two earthquakes – of 7.4 and 7.0 magnitude each – in the country's Gölcük and Düzce provinces. Almost 18,000 people died, and more than 45,000 were injured.
Then there is the East Anatolian fault line, which is the tectonic boundary between the Anatolian plate and the northward-moving Arabian Plate.
Additionally, there is the Aegean sea plate, which is also a source of seismic activity in the region.
According to one estimate, almost 95 percent of the country's land mass is prone to earthquakes, while about a third of the country is at high risk, including the areas around the major cities of Istanbul and Izmir and the region of East Anatolia.
As David Rothery, a geoscientist at the Open University, UK, told The Nature, "The tectonic plate that carries Arabia, including Syria, is colliding northwards into the southern rim of Eurasia and forcing Turkey to be squeezed out towards the west."
But Why Was the Latest Quake So Deadly?
The latest earthquake involved a fault rupture that was relatively shallow –about 18 km below the earth's surface – making surface movements more intense, according to Scientific American magazine.
As per the United States Geological Survey (USGS), only three earthquakes bigger than magnitude 6 have happened within 250 km of this location since 1970.
Monday's event is significantly bigger than the ones the area has experienced before, releasing more than twice as much energy as the largest previously recorded earthquake in the region.
It is well known that one of the main reasons people die in earthquakes is because of falling bricks and masonry. According to the USGS, the population of southern Turkey lives in structures that are extremely vulnerable to earthquake shaking, with unreinforced brick masonry and low-rise concrete frames.
Another reason why the impact was so deadly was that it occurred in the early hours, which meant that sleeping people were "trapped when their houses collapsed," Roger Musson, honorary research associate at the British Geological Survey, told AFP.
In Syria, the impact was made worse by the fact that 12 years of conflict have decimated building standards.
What About Aftershocks & Why Do They Occur?
After major earthquakes, there will be many smaller earthquakes known as aftershocks as the earth's crust readjusts to the changes in stress. Turkey has been rocked by about 200 aftershocks, according to The Journal.
While aftershocks are usually significantly smaller than the main shock, they can have equally devastating consequences, further damaging infrastructure that was damaged by the first earthquake and hampering rescue efforts.
For example, the May 2015 earthquake that struck Nepal was an aftershock of the earthquake that occurred in the country in April 2015.
While the main event in April killed about 8,800 people, the event in May claimed the lives of about 210 people.
How Does Monday's Earthquake Compare With Other Large Earthquakes?
The earthquake off the coast of Japan in 2011, registered as magnitude 9, caused widespread damage on the land and a tsunami, which was responsible for a major accident at a nuclear plant along the coast. Nepal's 7.8-magnitude earthquake in 2015 claimed nearly 9,000 lives.
The largest-ever earthquake was of magnitude 9.5, recorded in Chile in 1960.