Indonesia’s most active volcano erupted Wednesday with a river of lava and searing gas clouds flowing 1,500 meters down its slopes. The Associated Press reports that it was Mount Merapi’s biggest lava flow since authorities raised its danger level in November. The 2,968-meter volcano is on the densely populated island of Java and near the ancient city of Yogyakarta. Merapi’s last major eruption in 2010 killed 347 people.