3. Sakurajima, Japan
Sakurajima is one of Japan’s most active volcanoes, with frequent eruptions that spew ash over nearby towns. Located near Kagoshima city, it’s under constant surveillance due to its high activity levels. A major eruption could disrupt air traffic, displace communities, and cause significant damage to infrastructure. Experts warn that increasing seismic activity around its magma system signals a possible larger event in the near future.