National earthquake alerts
People worry a great deal about earthquakes. Is it possible to predict them? Chen says that while earthquake prediction technology is still a work in progress, we have already developed the means to provide alerts. By integrating monitoring instruments with other technology, upon detecting seismic waves the system is able to rapidly estimate the extent of the area that will be affected by the earthquake and the quake’s destructive power, and then issue an alert, giving people several seconds to take appropriate action before the shaking reaches them.
In 2016, a large earthquake centered in the Meinong District of Kaohsiung caused the collapse of a residential building in Tainan. The event prompted academia and the CWB to jointly develop an automated system for locating earthquakes that is capable of pinpointing a quake’s epicenter within a few seconds of its onset. The system then estimates the quake’s size and intensity across Taiwan, and passes this information to the earthquake rapid alert system for distribution. In the event of an earthquake of magnitude 5.0 or more, or a prediction that any locality will experience a seismic intensity of 4 or greater, the system is able to send out cellphone alerts to the public in the affected cities and counties within ten seconds. Chen says that with the automated location system already more than 60% accurate, the CWB hopes to reduce the notification time to seven seconds in 2023 and to five seconds in the future. “Meeting the five-second challenge would make our earthquake alerts the quickest in the world, faster even than in Japan.”
Last year, Professor Yen Horng-yuan and his team in the Earth Sciences Department at National Central University achieved a breakthrough in earthquake prediction by collating geoelectric, geomagnetic and ionospheric data on earthquakes of magnitude 6 or greater occurring between 2013 and 2018. Big-data analysis revealed corresponding anomalies that show promise as quake predictors. The CWB is planning a project for next year that will look further into the topic of detectable earthquake precursors.
More than 70% of Taiwan’s earthquakes occur off the coast of Yilan and Hualien. Chen explains that this area is a subduction zone at the edge of the Eurasian Plate, and is geologically complex, with a number of fracture zones. The Manila Trench, which runs from near Fangshan, Pingtung County, down to the Philippines, also has the potential to generate large earthquakes and tsunamis. Taiwan has therefore installed observation stations on the seafloor that are connected via submarine cables that run from Toucheng in Yilan to Fangshan, and southward from Fangshan along the eastern edge of the Manila Trench. This system has reduced the time it takes to calculate the parameters of an offshore earthquake from 35 seconds to just 20-some seconds and enabled the CWB to provide tsunami warnings. To date, only Taiwan, Japan and the US have established this kind of undersea monitoring network.
When a magnitude 7.8 earthquake on the Turkey–Syria border in February 2023 brought down tens of thousands of buildings and killed more than 50,000 people, the earthquake resistance of buildings became a hot topic once again.
Chang Wen-yen, dean of the National Dong Hwa University College of Environmental Studies and Oceanography and a research fellow with the Institute of Earth Sciences at Academia Sinica, says that the damage caused by earthquakes depends on the seismic resistance of old buildings. In addition to replacing such buildings or making them more earthquake-proof, we could further reduce earthquake harms by conducting non-destructive testing of the homes of disadvantaged residents, and perhaps providing them with grants to purchase or lease earthquake-resistant furniture.
“Can a butterfly flapping its wings in Brazil cause a tornado in Texas?” Dubbed the “butterfly effect” by American meteorologist Edward Norton Lorenz (it is an expression of “chaos theory”), the term highlights the idea that small events or phenomena can cause large, connected reactions to ripple through dynamic systems. The concept also helps remind us that the natural world is complex in ways that extend beyond the limits of scientific understanding. If we wish to thrive in spite of natural disasters, we can never cease our efforts to enhance community resilience.
Chen Kuo-chang, director of the CWB’s Seismological Center, says that though we can issue alerts when earthquakes occur, the quakes themselves are difficult to predict. Nonetheless, the CWB’s cooperation with academia to find earthquake precursors represents a big step forward in quake prediction.
The devastation wrought by Typhoon Morakot in August 2009 included landslides that wiped out Xiaolin Village in Kaohsiung’s Jiaxian District. Though the typhoon was the deadliest in Taiwan’s history, we overcame our grief and found the strength to rebuild.