STORY: Seismologists say Monday’s magnitude 7.8 earthquake that hit Turkey and Syria is probably going to be one of the deadliest this decade.

Only two others from 2013 to 2022 were of the same magnitude.

Compared to the 6.2 quake that hit Italy in 2016 and killed some 300 people - the Turkey Syria earthquake released 250 times as much energy - according to one expert.

So why was it so bad?

The epicentre of the quake was in the Turkish province of Gaziantep and at the relatively shallow depth of about 11 miles on the East Anatolian Fault.

It then radiated towards the northeast - bringing devastation to central Turkey and Syria.

The severity was due to the fact that the East Anatolian Fault is a strike-slip fault.

In those, solid rock plates are pushing up against each other across a vertical fault line, building stress until one slips in a horizontal motion - which releases a tremendous amount of strain.

That, in turn, can trigger an earthquake.

The San Andreas Fault in California is one of the world's most famous strike-slip faults.

In Monday's quake there was a more than 62 mile rupture between the Anatolian and Arabian plates.

Eleven minutes after the initial quake, the region was hit by a 6.7-magnitude aftershock.

A 7.5-magnitude quake came hours later, followed by another spasm in the afternoon.

Experts say activity is spreading to neighboring faults - and seismicity may continue for a while.

Monday’s quake already has the highest death toll in Turkey since 1999.

That year, a tremor of similar magnitude struck a region near Istanbul and killed more than 17,000 people.