How Taiwan’s tallest building survived the earthquake: Taipei 101 has a 660-ton pendulum that transfers energy to giant shock absorbers, allowing the 1,670-meter skyscraper to sway instead of topple

Taiwan has been hit by its strongest earthquake in 25 years, killing at least nine people, toppling buildings and even triggering tsunami warnings.

But amid the chaos, eerie footage shows the island’s tallest building – the $1.8 billion Taipei 101 skyscraper – gently swaying like a stick in the wind.

The building is 400 meters high and is equipped with an ingenious solution that reduces the total movement of the building during earthquakes and wind by 40 percent.

A 660-ton golden sphere, called the ‘tuned mass damper’, hangs from the 92nd floor of the building.

As the building moves in one direction, the steel sphere swings in the other direction, maintaining the overall balance of the building.

If wind or the force of an earthquake pushes the tower to the right, the sphere will exert an immediate and equal force to the left, canceling out the initial motion.

So even though the tower sways, it doesn’t fall over.

It is a so-called ‘passive damping system’, meaning it works without any external force or control – just gravity and the movement of the building.

Meanwhile, hydraulic pistons beneath the solid sphere absorb the energy and dissipate it in the form of heat.

Dr. Agathoklis Giaralis, professor of structural dynamics at City, University of London, described the smart spherical device as “like a pendulum.”

‘This steel sphere rests on damping devices designed to damp the relative swaying motion between the structure and the sphere, in a similar way to the shock absorbers in car suspensions,’ he told MailOnline.

While it’s strange to see a building sway, modern skyscrapers are built to be flexible, especially in earthquake-prone areas like Taiwan.

‘The materials they are made of are elastic, meaning they stretch or contract depending on the changing loads acting on them,’ Professor Antony Darby from the University of Bath’s Department of Architecture and Civil Engineering told MailOnline.

‘The amount of this deformation in an individual element (for example a beam or column) is very small, but if you multiply this across all elements in a tall building it can lead to significant lateral (sideways) movements.

“These movements are not dangerous to the structure itself, but if excessive, may cause discomfort to the occupants.”

Construction of Taipei 101 began in 1999 and was completed in time for New Year’s Eve 2004, when it finally opened to the public.

It is designed to resemble a bamboo shoot rising upward in eight sections – resembling a series of square buckets stacked on top of each other.

Each floor was installed with supporting steel ‘outrigger trusses’ running from the building’s core to the outer columns to increase the tower’s rigidity.

While other tall buildings hide tuned mass dampers, Taipei 101 is visible to visitors on the 88th through 92nd floors, making it something of a tourist attraction.

Unfazed tourists have even filmed the movement of the sphere during previous earthquakes, which occur regularly on the island.

Taiwan is a country particularly prone to earthquakes because it is close to the convergence of two tectonic plates: the Philippine Sea Plate and the Eurasian Plate.

Strong seismic activity can be detected along the boundaries of the tectonic plates, where the plates rub against each other and cause earthquakes.

However, Taiwan’s earthquake preparedness is “among the most advanced in the world,” said Stephen Gao, a seismologist and professor at Missouri University of Science and Technology.

“The island has introduced strict building codes, a world-class seismological network and widespread education campaigns on earthquake safety,” he said.

At the time of writing, Taiwan’s strongest earthquake in 25 years has killed nine people, while another 50 are missing.

Rescuers expect the total number of injuries and deaths to rise as the hunt for people trapped by the earthquake continues.

According to government statistics, the earthquake and aftershocks also caused 24 landslides and damage to 35 roads, bridges and tunnels.

Taiwan’s Earthquake Monitoring Agency said the earthquake had a magnitude of 7.2, while the US Geological Survey (USGS) estimated it at 7.4.