Research conducted on Jeju Island, a popular vacation spot just south of South Korea, has revealed that the island's massive volcano is likely still active, having erupted within the last 5,000 years.
The volcano, called Halla Mountain or "Halla-san," is the tallest volcano in all of South Korea, measuring about 45 by 25 miles across and 6,400 feet high.
Recent geological work led by Jin-Young Lee of the Korea Institute of Geoscience and Mineral Resources (KIGAM), revealed charcoal at the basaltic layer of Earth in the regions of Sangchang-ri, Seogwipo-si and Jeju-do. These charcoal samples carbon-dated to about 5,000 years ago, indicating recent volcanic activity.
According to the KIGAM, Lee's team even corrected for the possibility of charcoal contamination by taking into account other recently known volcanic activity around from Mt. Songak, a 7,000-year-old eruption, and eruptions which occurred around Byeongak Oreum 35,000 years ago.
Cross validating their findings using optically stimulated luminescence dating (OSL) - a method that determines how long ago minerals were last exposed to daylight - Lee was able to conclude that Halla Mountain should be classified as an "active" volcano.
But don't be alarmed. In accordance with basic geological knowledge, volcanoes are classified as "active" if they've erupted within the past 10,000 years. Other vacation spots, especially among the Hawaiian islands, boast their own active-but-dormant volcanoes too.
Still, the KIGAM is quick to point out that if Halla Mountain were to erupt, it wouldn't be a low-key lava flow spilling over a crater. It would be a true eruption in all its fiery glory, capable of covering the island with a fresh layer of charcoal researcher could unearth in another 5,000 years from now.
The institute says it's researchers will be keeping a close eye on Halla-San in the years to come.