Seismologists have said the 7.8 magnitude earthquake that struck Turkey and Syria on Monday is likely to be one of the deadliest this decade, with a rupture of more than 100 kilometres (62 miles) between the Anatolian and Arabian plates.
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Here's what experts believe happened under the earth's surface, and what to expect in the aftermath:
Where Did The Earthquake Originated?
The epicentre was around 26 kilometres east of Nurdagi, Turkey, at a depth of roughly 18 kilometres on the East Anatolian Fault. The tremor radiated northeast, wreaking havoc on central Turkey and Syria.
The East Anatolian Fault produced minimal substantial earthquake activity throughout the twentieth century. "If we just looked at (large) earthquakes recorded by seismometers, it would appear rather blank," said Roger Musson, an honorary research associate at the British Geological Survey.
According to the US Geological Survey, only three earthquakes measuring more than 6.0 on the Richter Scale have occurred in the area since 1970. However, in 1822, a 7.0 magnitude earthquake struck the area, killing an estimated 20,000 people.
Why Was The Earthquake So Destructive?
It was a large earthquake, measuring 7.8 on the Richter scale and rated as "major" on the official scale. It ruptured along a 100km (62 mile) fault line, inflicting significant damage to structures along the fault.
"Of the deadliest earthquakes in any given year, only two in the last 10 years have been of equivalent magnitude, and four in the previous 10 years," Prof Joanna Faure Walker, head of the Institute for Risk and Disaster Reduction at University College London, was quoted by BBC in its report.
However, it is not simply the tremor's intensity that causes havoc.
This occurrence occurred in the early morning hours, when individuals were sleeping inside.
The durability of the buildings is also an important consideration.
Dr Carmen Solana, reader in volcanology and risk communication at the University of Portsmouth, said: "The resistant infrastructure is unfortunately patchy in South Turkey and especially Syria, so saving lives now mostly relies on response. The next 24 hours are crucial to find survivors. After 48 hours the number of survivors decreases enormously," BBC reported.
What Kind Of Aftershocks Is Expected?
A 6.7-magnitude aftershock struck the area 11 minutes after the main quake. A 7.5-magnitude earthquake struck hours later, followed by a 6.0-magnitude tremor in the afternoon.
"What we are seeing now is the activity is spreading to neighbouring faults. We expect seismicity to continue for a while," Muson was quoted by Reuters in its report.
Aftershocks continued into the following year following the deadly 1822 event.
What Caused The Earthquake?
The Earth's crust is made up of different pieces known as plates that nestle beside one another.
These plates frequently try to move but are stopped by the friction of rubbing up against another plate. However, pressure can build up to the point when one plate abruptly jerks across, forcing the surface to shift.
In this event, the Arabian plate was travelling north and colliding with the Anatolian plate.
In the past, plate friction has been responsible for devastating earthquakes.
It generated an earthquake of a magnitude of 7.4 on August 13, 1822, much smaller than the 7.8 magnitude measured on Monday.
Even yet, the 19th-century earthquake caused massive damage to the region's cities, with 7,000 people killed in Aleppo alone. The devastating aftershocks lasted for a year.
What Might Be The Final Death Toll?
Earthquakes of equal size have killed thousands of people in crowded regions. In 2015, a 7.8-magnitude earthquake struck Nepal, killing over 9,000 people.
"It's not going to be good," said Musson. "It will be in the thousands, and could be in the tens of thousands."
Seismographs, which detect the seismic waves that flow through the Earth following a quake, are used to measure earthquakes.
For long years, scientists employed the Richter Scale, but now mostly use the Modified Mercalli Intensity Scale, which the US Geological Survey claims is a more accurate indicator of size.
The Richter scale is used to measure magnitude, whereas the MMI scale is used to assess intensity.