Istanbul began a three-day disaster drill on Tuesday, designed to test the preparedness of the sprawling city of more than 12 (m) million people to cope with a major earthquake.
Rescue teams rushed to help the injured amid overturned trains, a capsized ship and collapsed buildings, according to a scenario in which Turkey's largest city is hit by a magnitude 7.2 earthquake.
Across the city, officials were put through realistic approximations of the chaos of what could potentially be one of the world's worst natural disasters.
"By the exercises we are doing all around Istanbul, we are testing the field elements of rescue operations and the Disaster Management System,"
said Can Avci, Head of Istanbul Civil Defence, Search and Rescue Department.
Scientists estimate that if an earthquake of magnitude 7.0 or greater struck Istanbul, the devastation would be horrific.
Tens of thousands would die, countless others would be left injured or homeless and Byzantine or Ottoman buildings would be reduced to rubble,
The drill began at 11 am (0900 GMT) Tuesday with the Istanbul-based Kandilli Observatory seismology centre reporting a 7.2-magnitude quake
near the Princes' Islands in the Sea of Marmara off Istanbul.
Rescue workers pulled fake corpses from rubble and firefighters and police sped to help rescue the injured from collapsed buildings.
In other scenarios children in a school on the Asian side of the city that is bisected by the Bosporus huddled under their desks for several seconds, then were ordered by their teachers to run outside to the courtyard.
Nearby, sirens wailed as rescue workers rushed to a derailed train.
With the whirring of cranes and saws and the sounds of hammers breaking glass, they pulled out mock dead and tended to the injured.
Rescue teams also assisted people trapped under the debris of a mosque and rushed to save passengers of a ship sinking in the Bosporus as part of the drill.
Scientists say the greatest loss of life in a real earthquake would come as a result of the collapse of tens of thousands of structures erected irresponsibly and mostly illegally in the past four decades.
Geologists have urged the Turkish government since 1999 - when two earthquakes west of Istanbul killed more than 18-thousand people - to tear down some 50-thousand buildings that would probably collapse if a big quake were to hit Istanbul.
The earthquake drill, organised by, Turkish authorities, is due to last until Thursday.