Mount Semeru, on the island of Java, awoke on Sunday, spewing smoke and ash high into the air, prompting authorities to raise the volcano's alert status to the highest level.
According to local authorities, the volcano threw a column of ash and smoke up to a height of 1.5 kilometers, and now people have been forbidden to get within five kilometers of the volcano. There is as yet no information about casualties or damage.
Eyewitnesses shared videos of the eruption on social media.
Japanese authorities are now analyzing what repercussions this eruption might have on the nation:
"Japan's weather agency warned that there could be a tsunami on the islands of Miyako and Yaeyama in the southern prefecture of Okinawa," the Japanese news agency reported.
Semeru volcano erupted exactly one year ago on 4 December, killing more than 50 people. Semeru is the highest peak on the island of Java. There are almost 130 active volcanoes throughout Indonesia.