As Venezuela begins counting the cost of its deadliest quake disaster in over a century, a shattered economy and struggling health system threaten to slow recovery efforts.

A 7.2-magnitude earthquake and a 7.5-magnitude were less than a minute apart, said the U.S. Geological Survey. The second earthquake was the largest to hit the country since 1900.

As pledges of aid pour in from around the world, acting President Delcy Rodríguez has declared a state of emergency.

US Geological Survey estimates 44 per cent chance fatalities could exceed 10,000