7.4 magnitude quake hits Taiwan, strongest in 25 years

The powerful tremors that rocked Taiwan on Wednesday morning have damaged 125 buildings across the island, according to the National Fire Agency (NFA).

About half of the damaged buildings are in Hualien County, near the epicenter of the earthquake, according to local officials.

Four buildings in the county had partially collapsed, Hualien County Magistrate Hsu Chen-wei said at a news conference Wednesday.

Residents from three of the buildings have been safely evacuated, while search and rescue operations continue at the nine-storey Uranus Building, which is leaning to the right after the ground floor collapsed, Hsu said.

Twenty-two people have been rescued from the Uranus Building, with efforts still underway to contact one remaining resident, according to the National Fire Agency.

Taiwan was struck by its strongest earthquake in 25 years on Wednesday when a 7.4 magnitude tremor struck the island's eastern coast, collapsing buildings, killing at least four people and prompting tsunami warnings across the region.

Here's what you need to know:

Taiwan is regularly rocked by earthquakes due to its location on the Pacific Ring of Fire.

That's where the world’s most active volcanoes lie. It’s also where most earthquakes happen as tectonic plates push against each other, causing sudden releases of energy that result in tremors.

The “ring” stretches along a 25,000-mile (40,000-kilometer) arc from the boundary of the Pacific Plate, to smaller plates such as the Philippine Sea plate, to the Cocos and Nazca Plates that line the edge of the Pacific Ocean.

People most at risk from volcanic eruptions and earthquakes live in places that lie along the Ring of Fire, including Chile, Japan, the US west coast, and other island nations including the Solomon Islands to the western seaboard of North and South Americas.

Read more about the volatile arc.

Each time a major earthquake strikes, academics around the world pore over data to assess how the tremor played out and what lessons might be learned.

Alan Collins, a geologist at the University of Adelaide, said Taiwan "lies at an incredibly interesting plate tectonic setting."

Wednesday's quake, he said, "formed as a thrust, where the crust is compressed horizontally and a part of the Earth’s surface is pushed up over the bit in front of it — a bit like a piggy-back".

While Taiwan has ample experience with earthquakes, they tend not to produce large waves, Anja Scheffers, a tsunami expert at Australia's Southern Cross University said.  

The strength of a quake is also not the only thing that determines how dangerous it is. Building quality and the time of day a quake strikes are also key, according to experts.

Four people have been killed in Taiwan after a 7.4 magnitude earthquake rocked the island, according to Taiwan's National Fire Agency (NFA).

The deaths all occurred in Hualien County, near the epicenter of the quake, according to NFA.

At least 57 people have been injured, with most of them reported in Hualien, the agency added.

The agency earlier said that one of the fatalities was a hiker.

Japan is ready to provide support to its “important friend” Taiwan after it was struck by a 7.4 magnitude earthquake, Prime Minister Fumio Kishida said on Wednesday.

Kishida added he was “deeply saddened” and hoped that “all friends in Taiwan will be safe.”

Taiwan, Japan and the Philippines have all canceled their tsunami warnings, whilst the Pacific Tsunami Warning Center has said the threat to the United States has “largely passed”.

Tsunami waves were observed on the coasts of Taiwan and far southwestern Japanese islands after a 7.4 magnitude earthquake hit Taiwan on Wednesday morning.

But there were no immediate reports of any major damage caused by these waves.

In Taiwan: Tsunami heights reached nearly half a meter, or 1.5 feet, in Chenggong, approximately 100 km (62 miles) south of the quake’s epicenter. 

Observed tsunami heights are measured over open water and can reach significantly higher when they reach shore.

In Japan: A 0.3-meter wave impacted Okinawa Island, Naha airport spokesperson Hideaki Tsurodo told CNN, but no waves reached the airport and it was soon reopened.

In the Philippines: The Philippine Institute of Volcanology and Seismology said "no significant sea level disturbances" had been recorded since the earthquake.  

In the US: The threat of any tsunami risk has “largely passed”, the Pacific Tsunami Warning Center said. The update issued by its warning center in Honolulu said the evaluation was “based on all available data.”

It added that minor sea level “fluctuations” of up to 30 centimeters above and below normal tide levels could continue “over the next few hours.” 

The US Tsunami Warning Center also advised government agencies to “monitor conditions at the coast to determine if and when it is safe to resume normal activities.”

Tsunami waves less than 0.3 meters may be observed for the coasts of Guam, Indonesia, Northern Marianas, Palau, Philippines, South Korea, Vietnam, and Yap, the center added.

Taiwanese semiconductor company TSMC has temporarily evacuated manufacturing plants following a 7.4 magnitude earthquake that struck the island on Wednesday morning, the firm told CNN.

According to initial inspections, the company's construction sites are normal, but it "has decided to suspend work at construction sites for today, and work will resume following further inspections," according to a statement from TSMC.

One person has been killed in Taiwan after a 7.4 magnitude earthquake hit the island, based on preliminary data from Taiwan's National Fire Agency (NFA).

The person was hiking in Hualien County, NFA said.

Officials are still gathering more information about casualties, according to NFA.