The science behind the powerful earthquake in Myanmar and Thailand

Sagaing region near the Myanmar city of Mandalay caused extensive damage in that country and also shook neighbouring Thailand on Friday.

HOW VULNERABLE IS MYANMAR TO EARTHQUAKES?

Myanmar lies on the boundary between two tectonic plates and is one of the world's most seismically active countries, although large and destructive earthquakes have been relatively rare in the Sagaing region.

«The plate boundary between the India Plate and Eurasia Plate runs approximately north-south, cutting through the middle of the country,» said Joanna Faure Walker, a professor and earthquake expert at University College London.

She said the plates move past each other horizontally at different speeds. While this causes «strike slip» quakes that are normally less powerful than those seen in «subduction zones» like Sumatra, where one plate slides under another, they can still reach magnitudes of 7 to 8.

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WHY WAS FRIDAY'S QUAKE SO DAMAGING?

Sagaing has been hit by several quakes in recent years, with a 6.8 magnitude event causing at least 26 deaths and dozens of injuries in late 2012.

But Friday's event was «probably the biggest» to hit Myanmar's mainland in three quarters of a century, said Bill McGuire, another earthquake expert at UCL.

Roger Musson, honorary research fellow at the British Geological Survey, told Reuters that the shallow depth of the quake meant the damage would be more severe. The quake's epicentre was at a depth of just 10 km (6.2 miles), according to the United States Geological Survey.

«This is very damaging because it has occurred at a shallow depth, so the shockwaves are not dissipated as they go from the focus of the earthquake up to the surface. The buildings received the full force of the