Why was the Turkey-Syria earthquake so destructive?

Turkey is hit with a second earthquake, just hours after the first devastating disaster

More than 1,000 people have been killed by a powerful earthquake, which has caused devastation across the Turkey and Syrian border.

Buildings collapsed in seconds as the seismic waves, measured 7.8 magnitude, hit.

Multiple aftershocks, including a second 7.5 magnitude earthquake, was felt across the region, even as far away as Lebanon and Israel.

The disaster is one of the worst in the region in more than 100 years, with it being compared to the 1939 Erzincan earthquake. But why has the quake caused so much damage?

What is a shallow earthquake and why are they so dangerous?

One of the key reasons this morning's earthquake was so powerful was because it was a shallow earthquake - occurring just 17.9km below the earth's surface.

A shallow earthquake is when the seismic event happens close to the surface of the earth, between 0km and 70km. For context, a deep earthquake is 300 - 700 km. Shallow earthquakes are more dangerous as there is less distance for the waves to travel.

The deeper the earthquake the more energy the waves use and less impact they have when they hit the surface.

Shallow earthquakes tend to happen on mid-ocean ridges and transform margins.

Today's earthquake happened between the Anatolian and Arabian plates, which is a transform tectonic boundary - where the masses move away from, or slide past each other.

Prof David Rothery, Professor of Planetary Geosciences at The Open University, said: "The northward collision of the Arabian plate into Eurasia is forcing the intervening Anatolian plate westwards at a rate of about 2 cm per year.

"Because of friction along fault lines, the motion is not smooth.

"Instead strain builds up locally over years or decades until the accumulated stress is strong enough to overcome resistance and rock masses snap past each other in a sudden jerk. "

What is the Richter Scale and how does Monday's earthquake rank?

The Richter Scale measures the magnitude of earthquakes from 0 to 10, increasing by 10-fold each time.

Scientists used the Richter Scale for many years but now largely follow the Modified Mercalli Intensity Scale, which the US Geological Survey says is a more accurate measure of size.

The Richter scale measures magnitude, whereas the MMI scale measures intensity.

Building collapses to the ground as the earthquake hits

Prof Rothery said: "The earthquake's magnitude 7.8, which is large by global standards. 

"On average, there are fewer than 20 earthquakes exceeding magnitude 7.0 in any year."

He added: "Three earthquakes of magnitude 6 have happened in this area since 1970, and the northern Syrian city of Aleppo was severely damaged by magnitude 7 earthquakes in  1138 and 1822.”

How more than a decade of war has made things worse

The earthquake has caused devastation in the region, with buildings crumbling as the waves hit.

A huge impact zone has seen infrastructure destroyed, with damage extending from Syria’s cities of Aleppo and Hama to Turkey’s Diyarbakir - more than 330 kilometres (200 miles) to the northeast.

Nearly 3,000 buildings came down in Turkey, according to Erdogan.

Experts believe civil unrest in the area may have already weakened the buildings causing more casualties.

On the Syrian side, the area affected is divided between government-held territory and the country’s last opposition-held enclave, which is surrounded by Russian-backed government forces.

Turkey, meanwhile, is home to millions of refugees from that conflict.

Bill McGuire, Emeritus Professor of Earth Sciences at UCL, said: “Many of the buildings in the towns affected are simply not designed to cope with this level of strong shaking, and in Syria many structures have already been weakened by more than a decade of war.

"Sadly, I expect the death toll to rise significantly, and would not be at all surprised by a final death toll in the thousands.

"There have been dozens of significant aftershocks on the heels of the main quake, and these will continue for days, hampering rescue and relief efforts and potentially causing collapse of already damaged buildings.”

Extreme weather battered the regionIn the lead up to today's disaster, the region had been battered by extreme weather.

Forecasts for impacted city Gaziantep shows plummeting temperatures reaching as low as -6 degrees Celsius. As well as heavy rain and thunderstorms in the area too.Over the past two days (Feb 5-6) Turkish Airlines cancelled over 230 international and domestic flights via Istanbul Airport due to forecast adverse weather.

People were warned to monitor local media for weather-related updates and advisories and seek updated information on road conditions before driving or routing shipments.

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