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Indonesia’s Mount Merapi, a volcano on the island of Java, can be seen here letting off volcanic ash after an eruption on Dec. 29, 2021. Measuring 2,930 meters high, Mount Merapi is the most active among Indonesia’s approximately 120 active volcanoes. An eruption of Mount Merapi in October 2010 left 350 locals dead. (Yonhap News)

At around 2 am KST on Friday an underwater volcano erupted in the waters around the South Pacific island nation of Tonga for the first time. It went on to generate a tsunami at around 1 pm Saturday.

The eruption took place around 8,400 kilometers from Korea’s Jeju Island. The Korea Meteorological Administration said Sunday that Jeju and the southern South Korean coast would not be greatly affected by the eruption. While there were fluctuations of up to 15–20 centimeters in the sea level, those fell within the ordinary range, it explained.

Ham In-gyeong, a seismic analysis officer in the meteorological agency’s earthquake and volcano monitoring division, said, “While Japan issued a tsunami evacuation alert, the southern coast [of South Korea] and Jeju are farther away and have deeper waters.”

The Kermadec and Tonga plates are located in the South Pacific. As the Pacific Plate plunges beneath the Tonga Plate along a trench to the east of Tonga, the location has traditionally been a site of frequent volcanic activity.

“Like the trench to the east of Japan, the Tonga Trench shows frequent underwater volcanic activity,” explained Yun Sung-hyo, a professor of earth science at Pusan National, on Sunday.

According to this explanation, the volcano is not especially notable. The latest eruption had little impact in terms of dust because it occurred underwater.

Volcanic activity is a reflection of natural conditions that arise due to the flow of energy beneath Earth’s surface. This also means they are impossible to predict.

But on the basis of past volcanic activity figures, some scientists have warned of the potential for a major eruption to occur sometime this century.

A contribution published last August by the Intergovernmental Panel on Climate Change (IPCC) Working Group I to its Sixth Assessment Report stated, “Based on paleoclimate and historical evidence, it is likely [66–100% probable] that at least one large explosive volcanic eruption would occur during the 21st century.”

The report also predicted that “such an eruption would reduce global surface temperature and precipitation, especially over land, for one to three years, alter the global monsoon circulation, modify extreme precipitation and change many CIDs [climatic impact-drivers] (medium confidence).”

One of the drafting authors for the report was Lee June-yi, a professor at the Pusan National University Research Center for Climate Sciences.

“This means that there could be a large volcanic eruption at the scale not of the Tonga underwater volcano, but of Mount Pinatubo in the northern Philippines, which erupted [multiple times] between 1991 and 1993,” Lee explained Sunday.

“Based on various recent volcanic activity figures and paleoclimate data, we could see around one eruption of about that scale during this century,” she added.

The eruptions of Mount Pinatubo between 1991 and 1993 were intense enough to send volcanic ash and sulfur dioxide as high as 10 to 50 kilometers into the stratosphere. Due to dust covering the atmosphere, solar energy could not be absorbed, resulting in a global average temperature decline of 0.4 degrees Celsius.

Among the other massive volcanic eruptions that have caused casualties in the thousands to tens of thousands are those of Indonesia’s Krakatoa in 1883, Guatemala’s Santa Maria volcano in 1902, Indonesia’s Mount Agung in 1963, and Mexico’s El Chichon in 1982.

Min Seung-ki, a professor of environmental engineering at Pohang University of Science and Technology who also took part in drafting the IPCC’s Sixth Assessment Report, said, “Based on statistics about things like the times of past volcanic eruptions, we can conclude that a volcanic eruption big enough to have an impact on the global climate happens around once a century.”

"The chief message of the report is that the trend of global warming would not change, since the temperature would immediately recover after dropping for around two to three years,” he added.

Scientists have named the Korean Peninsula’s Mount Baekdu as another volcano that could erupt in the near future.

“The world has been focusing on the possibility of Mount Baekdu erupting, but there hasn’t been a lot of research,” Min said Sunday.

“All we have is the prediction that it could erupt, based on the possibility of an eruption happening once in a millennium in light of records pointing to a large-scale eruption in the year 946,” he added.

“At the time, it reportedly erupted in the winter, and it was affected by strong northwesterly winds. As a result, the dust traveled east toward the Japanese island of Hokkaido rather than rising high into the stratosphere,” he explained.

“But if another eruption were to happen in the summer, it could rise higher due to convection, where it would have an impact not just on the surrounding region but at a global level,” he predicted.

“In this case, it would have an effect on the global climate.”

By Choi Woo-ri, staff reporter

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