Indonesia's Mount Soputan volcano on the quake-and tsunami-hit island of Sulawesi erupted Wednesday, spewing volcanic ash 4,000 metres into the air. The state disaster agency warned people to stay at least four kilometres (two and a half miles) away but said there was no need to evacuate for the time being. Images showed an eruption visible for miles around, with a cloud of ash climbing in a large vertical column with a mushroom-shaped top. Soputan is around 1,000 kilometres from the town of Palu where a 7.5 magnitude earthquake triggered a tsunami that lashed the coastline killing almost 1,400 people. Indonesia is situated on the Pacific "Ring of Fire", a vast zone of geological instability where the collision of tectonic plates causes frequent quakes and major volcanic activity.