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Smoke and tremors: Fiery Mount Agung is just one of 127 active volcanoes in Indonesia

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“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.

Mr Syahbana’s colleagues have divided the archipelago’s volcanoes into three categories. The first, of which there are 69, are active volcanoes which have erupted at least once since 1600 (see map). The second are active but have not erupted since 1600. The third are potentially active openings in the earth’s crust, such as fumaroles. The first type, of which Agung is one, are monitored 24 hours a day by an observer in a station nearby, from which they can see the summit. They then feed back information to the main centre in Bandung, where 200 people pore over the data under large screens showing seismographs.

The volcanologists study the earthquakes that occur beneath a volcano; the bulges and other changes to its surface; and the type and volume of gas and ash it emits. Once unusual activity is spotted, such as a sudden increase in earthquakes, a team with extra instruments is sent out from Bandung.

“Volcanoes warn,” insists Surono, a former head of PVMBG. The most important thing to do, he says, is to listen to them. In September it was clear that new magma was rising in Agung, says David Pyle, a volcanologist at the University of Oxford. The government issued the highest level of alert and thousands of people were evacuated—prematurely, it turned out. The decision was based on the eruption of 1963, which was preceded by two days of earthquakes and produced calamitous flows of lava and ash within four weeks. This time around, it is as if the rock plug inside the volcano had become “harder” after 50 years of dormancy, says Mr Martanto. Finally, on November 21st, a phreatic (steam-driven) eruption seemed to suggest that magma was heating water at the top of the volcano. On November 25th the magma itself began to flow.

Eruptions, in short, are hard to predict with precision. Sinabung, on the island of Sumatra, erupted suddenly in 2010 and then again in 2013 and 2016. But before that it had not erupted for more than 400 years. As a result, PVMBG had not been monitoring it, and those living nearby were not prepared to evacuate. It is still puffing away; thousands of people have had to be permanently relocated.

Even when volcanoes are known to be active, and monitoring data abound, it is not easy to judge how imminent or cataclysmic an eruption might be. Such decisions, says Matthew Watson of the University of Bristol, require a “good deal of expert judgment under great uncertainty”. Call for an evacuation too early, and people might decide the risk is overblown and return to their homes.

Mr Surono describes how he monitored Merapi, another active volcano on the island of Sumatra, for years, conducting long discussions about how to evacuate those living nearby from their homes if need be. Late on October 24th 2010 he decided that an eruption was at hand and called for an evacuation. The National Disaster-Management Authority managed to get some 350,000 people to safety before the eruption actually occurred, on the evening of the 25th. Such a short interval between issuing an alert and an eruption was ideal, he says proudly, as it minimised the time evacuees spent away from their homes. Many people refused to leave, however, and more than 350 died.

Indonesia’s budget for responding to natural disasters, including eruptions, is just 4trn rupiah ($296m). With so many volcanoes to monitor, and with such limited resources, the “agency is spread pretty thin across the archipelago,” says Clive Oppenheimer of the University of Cambridge. Even as Agung rumbles away, Sinabung is erupting again at the far end of the country. The harried Mr Syahbana seems to spend much of his time travelling.

The spread of smartphones does at least mean that locals, who in the past might have been more likely to listen to village elders or shamans than scientists, can receive expert advice directly. Technology helps with the monitoring too: drones can continue to inspect craters long after they have become too dangerous for humans to visit. Indonesia’s volcanologists are getting help from abroad as well. The monitoring centre makes use of satellite images and other research provided by colleagues in America, France and Japan, for example. Even so, a lot is resting on the judgment of a handful of sleep-deprived scientists holed up at Agung’s feet.

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Julio Marchi ©

Publisher / Editor at BS News & Media Services
A free thinker, not labelled as anything, not associated with any party, not part of any group or engaged with any religion... A simple guy tired of the nowadays bullshit who decided to promote more serious debates about what is really happening hoping to bring back intelligence to the superficial and shallow news & headlines that unfortunately took over the existing media scene.
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