Mount Paektu: the geological mystery on the ChinaNorth Korea border Matthew Morris

Mount Paektu, also known as Mount Changbai, is a stratovolcano located directly on the border between China and North Korea. The volcano has immense cultural significance to the Korean people; it is mentioned in both the North and South Korean national anthems. However, its geological setting has been a mystery to scientists for decades. Many of the world’s most dangerous volcanoes are concentrated along the infamous ‘ring of fire’– a

chain of volcanoes located above subduction zones, where oceanic tectonic plates are descending down, or subducting, beneath the less dense continental

However, as is always the case with nature, there are outliers. Mount Paektu is over 500 km from the nearest subduction zone, with no observed crustal thinning, and no identified mantle plume. So, why is there volcanism? Understanding this volcano is not just of scientific intrigue; Mount Paektu is still active and a large eruption could put “ Mount Paektu is still active and a many larger cities, large eruption could put many larger including Seoul and Beijing, at significant cities, including Seoul and Beijing, at risk. Its 946 A.D. eruption was one of significant risk." the largest eruptions ever recorded as it plates. Volcanism occurs at subduction produced enough tephra to blanket an zones due to water released from the area the size of New York City in subducting oceanic plate melting the almost 150 metres of ash. overlying mantle. This forms magma Unfortunately, the volcano has which can rise through the crust, historically been off-limits to causing devastating eruptions. Other geologists wanting to study its inner volcanoes, such as Kīlauea in Hawaii, workings. Both China and North Korea are found away from subduction zones have traditionally been hostile to and are the results of mantle ‘hotspots’. international research efforts. But Volcanoes are also found along following increased activity during the divergent plate boundaries, such as the early 2000’s, the North Korean Mid-Atlantic Ridge or the East African government took an unprecedented Rift Valley, where the crust is very step to call on the wider science thin. community for help in understanding These three forms of the volcano and its potential risk. After volcanism should account for the years of visa issues and coordination, location of every volcano on Earth. in 2011 two scientists from the UK, James Hammond and Clive Oppenheimer, joined North Korean scientists to uncover Mount Paektu’s hidden secrets. Thanks to the international cooperation, our understanding of this volcano is much clearer. Using an analytical technique called seismic tomography, it is now thought that a portion of subducting oceanic plate has travelled much further laterally than expected, in an area known as the Mantle Transition Zone. However, there is still significant debate regarding this, as recent tomography shows a possible hole in the subducted plate, potentially generating magma through an entirely different process. Although the geological findings are important, there are wider issues to address here, namely the importance of international cooperation for the advancement of science. This is a problem that takes many forms, including the issue of primarily western scientists not engaging with local researchers when studying in developing countries. For the good that comes out of scientific advancement, we must ensure everyone is involved and there are no barriers for global research.