Liu watched intently as rescuers carefully picked their way through the remains of a warehouse that crumbled like a house of cards Wednesday during Taiwan's strongest earthquake in 25 years, telling it "was like a mountain collapsed".

Propping ladders against the debris, the rescue workers managed to pluck 50 survivors from the destroyed building in Liu's New Taipei City, just outside the capital.

The building was about 60 years old and had housed a printing press, said Liu, who lived next door.

The 7.4-magnitude earthquake that struck at around 8:00 am local time (0000 GMT), reduced the building to jagged concrete blocks, steel bars, bricks and tangled wiring.

Residents of nearby buildings appeared to be unaffected, though they felt the intense shaking from the morning quake.

"Many of the decorations at home fell on the floor, but people were safe," said Chang, who lives near the printing press. "We were very lucky."

The quake was felt across Taiwan, with more than 100 aftershocks unnerving the island of around 23 million.

Its epicentre was in eastern Hualien county, a mountainous region known for its picturesque trails and seascape views.

At least nine people died in the quake -- all in Hualien -- with three killed on a hiking trail and two crushed in their vehicles by boulders from landslides.

More than 800 were injured across Taiwan.

Images filmed by a train passenger and obtained by verification team showed a landslide near one Hualien trail, sending up a cloud of white dust across its mountain ridges.

A driver shot a video of another landslide spilling onto a road near the region's famed Taroko National Park, with cars emerging from a cloud of sand and dust.

Some buildings around Hualien were left tilting dangerously, with military personnel climbing into the structures using ladders.

A group of firefighters used a cherry picker to reach a window and hand tools to workers inside.

On the island's western coast in Taichung -- Taiwan's second-largest city -- a road was cut off by a landslide, with massive boulders falling from a mountain ridge and blocking off traffic.

The shallow quake -- the United States Geological Survey put it at about 34.8 kilometres deep -- was "felt all over Taiwan", said Wu Chien-fu, director of Taipei's Central Weather Administration's Seismology Center.

"It's the strongest in 25 years since the (1999) earthquake," he said, adding that authorities were not ruling out subsequent tremors in the next three days.

The 1999 earthquake hit central Taiwan, killing around 2,400 people in the deadliest natural disaster in the island's history.

Taiwan's defence ministry said it had deployed cargo planes to take dozens of rescuers to Hualien, where people were reportedly trapped in tunnels that carve through the mountains.

- 'Really scared' -

Taiwan is accustomed to earthquakes as the island lies near the junction of two tectonic plates.

Buildings in major cities are made to withstand strong tremors, and while there are high-rises in the capital Taipei, people tend to prefer to live in structures less than 10 storeys high.

In New Taipei City, Mayor Hou Yu-ih surveyed the scene of the printing press collapse with rescue workers, and reassured reporters that all 57 people in the building had made it out -- with just one injured.

Chang, who lived nearby, said the 1999 quake was the worst she had ever experienced.

"Most people were asleep (when it happened) but I was not so I clearly felt it -- it was very serious, far more serious than this time," she said.

But one woman in Hualien said she was "really scared" because Wednesday's quake lasted a long time.

"I am used to earthquakes but this is the first time I was so scared that my hands kept shaking," she said in a Facebook post.