A helicopter rescued six miners to safety from a Taiwan quarry on Thursday as rescuers worked to free scores of people trapped in highway tunnels after the island's biggest earthquake in a quarter of a century.

Nine people were killed and more than 1,000 injured in Wednesday's magnitude-7.4 quake, but strict building regulations and widespread public disaster awareness appear to have staved off a major catastrophe on the island.

Reporters saw dozens of residents of the worst-hit city spent a night outdoors rather in apartments still being shaken by aftershocks, and a massive engineering operation was under way to fix damaged roads and prop up tilting buildings.

Dramatic video released on Thursday by the island's Central Emergency Operation Centre showed a helicopter flying two sorties to pluck six miners trapped in a gypsum quarry in Hualien county, near the epicentre of the quake.

Rescuers were reported to know the whereabouts of dozens more people trapped in a network of strongly built tunnels in the county, a feature of the roads that cut through the scenic mountains and cliffs leading to Hualien City from the north and west.

Meanwhile, Premier Chen Chien-jen said after a briefing at an emergency operation centre in Hualien that he hopes that the emergency service find those who are stranded and unaccounted for.

The island has been shaken by over 300 strong aftershocks since the first quake, and the government warned people to be wary of landslides or rockfalls if they ventured to the countryside for Qingming, a two-day public holiday that began Thursday