Blasts from the Shinmoe crater were so strong that residents in the nearby city of Kirishima reported feeling as well as hearing them.
The resounding booms and falling debris prompted hundreds of people living near the mountain to flee their homes.
Ash soared nearly 10,000 feet into the sky along the border of Kagoshima and Miyazaki prefectures on Japan’s southern island of Kyushu.
Vulcanologists caution that a dome of lava is building within the volcano’s crater, but were uncertain if it would burst out and spill over the mountain’s rim.
Activity on Feb. 1 was the strongest since a 1959 eruption, but was not expected to spread to other volcanoes nearby.
The volcanic complex has produced numerous eruptions since first observations of its activity were recorded in the year 742.
Other strong eruptions occurred in 788, 1716, 1717, 1771 and 1822. The Shinmoe crater was used as a location for the 1967 James Bond film, “You Only Live Twice.”