[Reading Science] Earthquakes Unavoidable in Buan and New York, Is There No Way to Predict Them?

Disappearing Safe Zones on the Korean Peninsula, Early Acquisition of Fault Zone Information Needed
Earthquake Occurrences Increase but Prediction Remains Difficult
Overseas Developments in GPS-Based Earthquake Prediction 2 Hours in Advance... 100-Fold Technological Advancement Required from Current Level

On the morning of the 12th, a magnitude 4.8 earthquake that occurred in Buan-gun, Jeollabuk-do, once again reminded us that "the Korean Peninsula is not an earthquake-safe zone." Since the 2017 Pohang earthquake, there had been no major earthquakes causing significant damage, leading to a sense of complacency. This earthquake, which occurred in a region previously considered scientifically unrelated to seismic activity, shocked the public even more.

On April 5th, New York City in the United States was also shaken by a magnitude 4.8 earthquake in nearby Hunterdon County, New Jersey. It was the first earthquake in this area in 140 years. Because earthquakes are rare in New York City, the local authorities' slow response drew harsh criticism from citizens.

Although the earthquakes of the same magnitude in Buan and New York did not cause casualties, they left the challenge of strengthening scientific preparedness to prevent damage from larger earthquakes.

◇ Academia forecasts possible earthquakes of magnitude 6.0, worst-case scenario up to 7.0

The Korean Peninsula lies within the Eurasian Plate. Generally, earthquakes frequently occur in regions located at plate boundaries. This is why earthquakes are common in plate boundary areas such as California in the United States and Japan.

Compared to Japan or Taiwan, South Korea has a much lower earthquake risk, but the increasing frequency of earthquakes in recent years can be statistically confirmed. Recent earthquake occurrence graphs show a clear upward trend, which has become more pronounced since the 2011 Great East Japan Earthquake. Scholars analyze that the eastern part of the Korean Peninsula is being pulled toward Japan, causing the peninsula to widen by about 3 cm compared to the past, weakening the ground and leading to more frequent earthquakes.

As the frequency of earthquakes increases, concerns have also been raised about the possibility of larger magnitude earthquakes occurring. The recent earthquake in Buan, Jeollabuk-do, previously considered an earthquake-safe zone after the 2016 Gyeongju (magnitude 5.8) and 2017 Pohang (magnitude 5.4) earthquakes, suggests that even the densely populated Seoul metropolitan area may not be safe from earthquakes.

According to the Korea Institute of Geoscience and Mineral Resources, the maximum magnitude earthquake that can occur on the Korean Peninsula is estimated to be about 6.0. An earthquake of this magnitude can cause houses to collapse and significant damage depending on the epicenter's location. In the worst case, a strong earthquake of magnitude 7.0 could occur, which would be 63 times more powerful than the 2016 Gyeongju earthquake.

◇ Accelerate fault surveys on the Korean Peninsula... Research on neighboring countries' information also needed

So far, South Korea's earthquake response has focused more on improving the speed of earthquake warnings rather than prediction and on understanding fault zone information in the southeastern region. However, this policy has limitations. Although warning speeds have increased and responses such as seismic design of buildings have been strengthened, fault zone information is limited to the southeastern region, leaving the recent Buan earthquake unprepared for. It is urgent to complete fault surveys on the Korean Peninsula quickly. Currently, surveys are underway in the Seoul metropolitan area and Chungcheong region following the southeastern region, while surveys in Honam will start in 2027 and in Gangwon in 2032.

The research team from the Korea Institute of Geoscience and Mineral Resources is conducting a field survey of the fault zone. Photo by Jiyayeon

Professor Hong Tae-kyung of Yonsei University's Department of Earth System Sciences explained, "The Great East Japan Earthquake caused stress imbalances across the Korean Peninsula, leading to a surge in earthquakes that has somewhat decreased now, but stress is transferring to deeper parts of the ground, increasing the number of deep-focus earthquakes." This means rapid surveys are urgent due to possible changes in fault zones.

It is also necessary to understand submarine fault information. Earthquakes occurring under the sea affect land and can cause damage from tsunamis. Their wavelengths are as large as those of land earthquakes. Research on active submarine faults began in 2018 to create a submarine fault map around the Korean Peninsula, but there is still a long way to go.

Some argue that research on domestic earthquakes alone is insufficient. This is because the influence of overseas earthquakes cannot be ignored. Expanding domestic earthquake research to the Northeast Asia region, including plate boundaries around South Korea, is necessary for comprehensive, all-around earthquake response.

◇ Overseas, earthquake prediction technology using GPS can forecast earthquakes 2 hours in advance... but limitations remain

Is it possible to predict earthquakes in advance through science and technology? Predicting natural phenomena like earthquakes remains difficult even with advanced technology. There are few cases where earthquake prediction has successfully reduced damage. This is because the physical understanding of stress accumulation and release processes in earthquake fault zones caused by tectonic plate movements is insufficient, and the ability to observe these processes precisely is limited. Historically, linking abnormal animal behavior to earthquake prediction symbolizes human helplessness against earthquakes and natural phenomena. However, scientists are not giving up.

The most recent notable earthquake prediction study was published last year in the international journal "Science," where precursory symptoms occurring on faults two hours before an earthquake were detected via satellite. Professor Quentin Bletery's research team at C?te d'Azur University in France analyzed GPS time-series data from over 100 large earthquakes worldwide and identified precursory movements on faults two hours before major earthquakes. These movements were so subtle that seismometers could not detect them. However, being able to predict an earthquake two hours in advance could significantly reduce damage by evacuating residents, making it a breakthrough in earthquake prediction technology. Nevertheless, the research team stated that this technology requires GPS that is 100 times more precise than current systems for accurate forecasting.