Shanghai residents feel tremors from Taiwan earthquake, expert provides insights

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People's Square

3rd April 2024 – (Shanghai) The China Earthquake Networks Centre officially announced that a magnitude 7.3 earthquake struck the sea off Hualien County, Taiwan at 7.58am local time today. The epicentre was located at a latitude of 23.81 degrees north and a longitude of 121.74 degrees east, with a depth of 12 kilometres.

The Shanghai Seismological Bureau’s official Weibo account released a statement around 9am, stating that the earthquake in Taiwan was approximately 825 kilometres away from People’s Square in Shanghai. Many residents of high-rise buildings in Shanghai reported feeling the tremors. Based on historical earthquake experiences, strong earthquakes in Taiwan can have an impact on some high-rise buildings in Shanghai, although they do not pose a significant threat to the city.

Why did Shanghai experience noticeable tremors from an earthquake in Taiwan? How should Shanghai residents respond when they feel the tremors? What are the potential effects of the Taiwan earthquake on Shanghai? In an interview with ThePaper.cn on the morning of April 3, Mr. Wen Yanlin, Senior Engineer at the Shanghai Seismological Bureau, provided insights into these questions.

Shanghai’s Soft Soil Amplifies Seismic Vibrations

According to Wen Yanlin, based on historical records, earthquakes with a magnitude of 6 or higher in Taiwan can cause varying degrees of tremors in some high-rise buildings in Shanghai. Therefore, considering the larger magnitude and wider range of this 7.3 magnitude earthquake in Taiwan, it is expected that a significant number of high-rise buildings in Fujian, Zhejiang, and Shanghai experienced noticeable tremors.

“Many residents of high-rise buildings may have felt their furniture shaking or objects swinging. The tremors were quite noticeable,” explained Wen Yanlin. Due to the presence of thick layers of soft soil, ranging from 300 to 400 meters deep, in Shanghai’s ground, distant earthquakes with long-period seismic waves are amplified to some extent. When the natural frequencies of certain high-rise buildings in Shanghai align with the long-period seismic waves, resonance occurs, intensifying the swaying motion.

In fact, it is not only earthquakes in Taiwan that can affect Shanghai. Wen Yanlin revealed that during the 2008 Wenchuan earthquake, high-rise buildings in Shanghai’s Lujiazui area were also affected, leading many office workers to evacuate the buildings due to strong tremors. Similarly, the Great East Japan Earthquake in 2011 made Shanghai residents empathize with the experience

“Our office was shaking violently, and everyone in the building rushed downstairs. I had to descend more than 20 floors in the morning. It was truly unbearable,” recalled Ms. Wang, a Shanghai resident, describing the situation earlier today.

When experiencing noticeable tremors in high-rise buildings, is it appropriate to rush downstairs to find shelter on the ground floor?

Wen Yanlin advised that, in reality, when feeling tremors in tall buildings, it is safer to seek refuge in nearby confined spaces such as bathrooms. If people hastily descend the building when feeling tremors, they may be at risk of injury due to falling objects. It is better to wait until the tremors subside and then evacuate in an orderly manner.

“Newly constructed buildings in Shanghai strictly adhere to the seismic design standards of 7 degrees. Generally, strong earthquakes occurring in distant areas do not cause significant damage,” said Wen Yanlin. Therefore, residents should not overly panic when feeling tremors.

Wen Yanlin disclosed that as of 12pm today, there have been a total of 21 aftershocks measuring above 4.0 in the sea off Hualien County, Taiwan. The largest aftershock reached a magnitude of 6. If aftershocks measuring 6 or higher occur, some high-rise buildings in Shanghai may experience tremors, but they will not cause destructive effects. Based on historical earthquake analysis, the current earthquake in Taiwan will not significantly affect seismic activities in the eastern coastal region of China.

Wen Yanlin added that according to monitoring data from the Shanghai Seismological Bureau, the largest earthquake on land in Shanghai’s administrative area since 1970 was a magnitude 3.1 earthquake in Qingpu last year. The largest earthquake in the nearby waters occurred in 1971, measuring 4.9 at the mouth of the Yangtze River. Overall, the level of seismic activity in Shanghai is currently not high.

“We will take this opportunity, including the annual National Disaster Prevention and Reduction Day on 12th May, to promote earthquake prevention and reduction knowledge and earthquake safety skills,” said Wen Yanlin. Only by acquiring relevant skills can individuals protect themselves during an earthquake.