Fiery Mount Agung is just one of 127 active volcanoes in Indonesia

“THE hardest bit of the job is having enough sleep,” admits Martanto, a 29-year-old geophysicist at the monitoring centre for Agung, a volcano in Bali which started erupting on November 25th. For the past two weeks he and half a dozen others have relocated from Bandung, in West Java, to keep watch on Agung every hour of the day, occasionally in continuous 32-hour shifts. Their base is rudimentary: a room plastered with maps, graphs and lists of telephone numbers. In one corner sits a seismometer, a cylindrical machine which measures earthquakes; in another corner a radio is on standby, in case of an emergency. Outside, a huge plume of ash spews from the crater at Agung’s peak. The smell of sulphur hangs thickly in the air.

Indonesia is the most volcano-pocked country in the world, with 127 active ones. It was home to both the biggest eruption of modern times, that of Tambora in 1815, and the second-biggest, of Krakatoa in 1883. Agung’s previous eruption, in 1963, was the most explosive of the 20th century in Indonesia. Gas, rock and ash were ejected to a height of 25km above the crater. More than 1,000 people died. Previous eruptions, in 1843 and 1710-11, were similarly destructive, says Devy Kamil Syahbana of the Volcanology and Geological Disaster Mitigation Centre (PVMBG) in Bandung.