Mount Ibu, a volcano, erupted on Monday, spewing thick gray ash and dark clouds 16,400 feet into the sky for five minutes, officials said. “The volcanic earthquakes are still intense so there is a potential for a future eruption,” Hendra Gunawan, chief of the Center for Volcanology and Geological Hazard Mitigation said. After an eruption on Friday, the center raised the alert level for Mount Ibu from 2 to 3, the second-highest level, which widens the radius of the area which should be vacated. Local authorities have prepared evacuation tents, but no evacuation order has been reported yet. Officials advised residents and tourists not to conduct any activities within 3 miles of Mount Ibu’s crater. More than 13,000 people live within a 3-mile radius of the northern side of the crater, Gunawan said. The 4,347-foot volcano is on the northwest coast of the remote island of Halmahera. Indonesia, an archipelago of 270 million people, has 120 active volcanoes. It is prone to volcanic activity because it sits along the Ring of Fire, a horseshoe-shaped series of seismic fault lines around the Pacific Ocean.