Read More: Live Science
Indonesia's Mount Agung is spewing towering clouds of ash, raising concerns that the giant 10,305-foot-tall (3,140 meters) volcano might have a big eruption soon, according to news sources. The volcano, located on the eastern side of the resort island of Bali, began erupting ash last Tuesday (Nov. 21). These ashy plumes have reached heights of about 9,800 feet (3,000 m), and have led the government to ask about 100,000 people on Bali to evacuate, according to the Indonesian National Board for Disaster Management. "The volcano's alert level has been raised to the highest level," senior state volcanologist Gede Suantika told The Jakarta Post. "Constant tremors can be felt." The volcano's recent rumblings began in September, leading authorities to evacuate more than 140,000 people living near the volcano at that time, The Jakarta Post reported. But Agung's alarming activity dropped in October, prompting the government to lower the warning to the second-highest level and allowing many people to return home. That changed last week, when the volcano belched out steam — an episode experts are calling a phreatic eruption, when magma heats groundwater and causes it to evaporate instantaneously, sometimes carrying rocky debris.