A volcano in Southwest Japan's Kagoshima Prefecture had small eruption, according to the prefectural weather agency on Wednesday, marking the first eruption after Japan's Meteorological Agency (JMA) raised its alert level for the volcano to level 4 on Saturday.

Meanwhile, the JMA said that fire light generated by lava was observed on the volcano called Sakurajima in early hours Wednesday, adding that it is highly possible that the volcano will erupt in large scale.

Increasing number of volcanic earthquakes were detected around the small volcanic island by the JMA, which also said that the volcano is swelling, a sign of possible eruption.

A level-4 volcano alert means local residents should be prepared for evacuation, and some of islanders on Sakurajima have evacuated.

The volcano last erupted in August 2013, with volcanic ashes being spewed some 5,000 meters into sky.