A massive eruption of Mount Agung volcano on the Indonesian island of Bali could happen any time, scientists say. It has been giving off volcanic ash with increasing intensity since 21st November 2017. Minor eruptions, blasting out pale grey plumes of ash and steam (caused by magma heating water), occurred at first. A more recent plume, rising nearly three kilometres (two miles) into the atmosphere, is darker grey, indicating it is being driven by the magma itself—molten rock rising up the inside of the volcano. A glowing ring of red-hot lava inside the crater of Mount Agung is now clearly visible. It is another sign that there will be an eruption soon.

Approximately 100,000 people in 22 villages within the 10-kilometre (6-mile) “red” danger zone around the volcano have been told to leave immediately. Some 40,000 people have already moved away and the airport has been closed (volcanic ash can affect planes’ engines), causing tens of thousands of travellers to be stranded. The main hazard of a large eruption are the high-speed avalanches of hot rocks, dust and gas, known as pyroclastic flows, that surge down the volcano’s slopes. Mudflows, known as lahars, are also a threat.



Mount Agung began experiencing high seismic activity in September 2017: hundreds of earthquakes took place inside the volcanic cone, caused by the movement of magma. Scientists warned that the increase in the quakes' force and intensity—and the fact that they are occurring nearer and nearer the surface—indicated that an eruption was imminent. Emissions of gas from the deep crater at Agung's summit and bulging on the volcano’s sides were both further signs that magma was being forced up towards the top of the volcano, releasing gas and steam as it did so.

Mount Agung is one of many active volcanoes in the Ring of Fire, a string of volcanoes and earthquake zones that runs round the edges of the Pacific Ocean and through the Indonesian archipelago. Agung last erupted in 1963. That event was also marked by an increased frequency in earthquakes before the eruption took place. Devastating pyroclastic flows—high-speed avalanches of hot gas, ash and rock—hurtled down the slopes of the volcano, causing the deaths of more than 1100 people.

Around 140,000 Balinese people who live in the danger zone around the volcano have been offered temporary shelter in local village halls and sports centres. Some cross back and forth into the danger area every day to check the livestock they left behind. At the Goa Lawah Hindu temple, daily prayers continue at the site of a cave that many Balinese believe is connected to the volcano's energy.