A farmer tends her crops on Bali against the backdrop of Mount Agung. PHOTO: DARREN WHITESIDE/REUTERS
By
Jon EmontSept. 29, 2017 7:44 a.m. ET
Mount Agung, a giant stratovolcano that dominates northern Bali’s landscape, is likely to blow, according to Indonesia’s national volcano monitor. But nobody knows when.
The volcano last erupted in 1963, when local scientists lacked the technology to predict volcanic outbursts, killing more than 1,000 people. This time, Indonesia is using modern seismic and satellite equipment to monitor the mountain.
Even with such technology, volcanologists say it is impossible to predict exactly when the volcano will blow. Meanwhile, the risk of an eruption keeps farmers from their fields and threatens to squeeze Bali’s tourism industry.
SHAKING UP HISTORY
Though Agung’s eventual eruption isn’t expected to be felt much beyond the island, some Indonesian volcanic eruptions have altered the course of history.
Toba, some 75,000 years ago: A volcano in North Sumatra released 2,000-3,000 cubic kilometers of ash into the air, in what is thought to be the largest volcanic eruption in human history.
Samalas, 1257: A volcano on Lombok island, just east of Bali, erupted, sending sheets of ash as far as Antarctica.
The eruption was recently linked to widespread famine the following year in England.
Tambora, 1815: A volcano erupted on the eastern Indonesian island of Sumbawa, creating a massive tsunami that killed nearly 100,000 people. Ash from the eruption led to a gloomy summer in Europe, inspiring Mary Shelley to begin writing Frankenstein.
Krakatoa, 1883: A massive series of eruptions destroyed the small island of Krakatoa, just west of Java, and turned European sunsets bright red for months, lowering global temperatures by more than 2 degrees Fahrenheit the next year. Scholars have credited red sunsets as inspiration for the reddish sky of Edvard Munch’s painting “The Scream.”
Indonesia’s national volcano monitor has said an eruption may be imminent but that the current seismic activity could continue for weeks. It is difficult to estimate timing, in part because modern equipment wasn’t available to measure the last eruption, so scientists don’t know how current activity compares with the lead-up to eruptions past.
“Managing the crisis at Agung is a new thing,” said Dr. Devy Syahbana of Indonesia’s Center for Volcanology and Geological Hazard Mitigation. “There was no instrumental documentation before the eruption of Agung in 1963.”
When Agung began belching steam and sulfuric gas a week ago, prompting the evacuation of more than 130,000 Balinese, the island’s volcanologists had already begun detecting tremors beneath the base of the volcano.
Recent seismographic measurements indicate earthquakes are rising closer to the base of the volcano, suggesting that red-hot magma is coursing up through the mountain. Satellite data tells a similar story, showing new thermal areas in the summit crater, again implying that magma is pushing upward.
Meanwhile, tiltmeter data, which measures deformation in the volcano’s shape, suggest the mountain is inflating with magma. As magma and sulfuric gases push toward the peak, pressure builds, eventually leading to an explosion.
Scientists say an eruption of Agung would lead to pyroclastic flows that would kill anyone in their path and devastate farmland, as happened in 1963. Such flows—made up of gas, ash and rock—are produced by composite volcanos like Agung.
Bali on High Alert for Possible Mount Agung Volcano Eruption
More than 100,000 people have evacuated the Indonesian tourist island
A woman and child sit in a tent at an evacuation center for people living near Mount Agung, a volcano on the highest alert level, outside a sports arena in Klungkung, on the resort island of Bali, Indonesia.
DARREN WHITESIDE/REUTERS
The most recent official notice warns that the magnitude of earthquakes beneath the volcano is increasing and that “the probability of an eruption is higher than the probability of no eruption.”
Independent experts, less cautious, say that an eruption is imminent. “It’s much more likely to keep going now then to stop,” said Richard Arculus, an emeritus professor of geology at Australian National University.
But scientists say they lack the tools to predict precisely when an eruption will occur, even in situations like the current one, where they believe an eruption is likely.
Karen Fontijn,a physical volcanologist and postdoctoral research associate at Oxford University, researched Agung’s eruption patterns over the past 5,000 years by using carbon dating to analyze underground ash layers. Her research suggests that Mount Agung’s eruptions tend to be of a fairly consistent scale. But the historical data don’t indicate how long the lead-up to an eruption will be.
Earlier
Indonesia's disaster agency said an eruption appears imminent at Mount Agnug after a half-century of calm. Photo: Getty Images
Because of the uncertainty about timing, some Balinese farmers are entering the eruption zone during the day to tend to their land, according to Hevy Umbara, a geologist volunteering near Mount Agung to warn locals of the dangers of returning to their fields.
“I worry farmers will become victims,” he said. “We need a solution so that farmers don’t enter the danger zones.”
Farmers may have to wait a long time to return to their fields.
“We really can’t tell when it will erupt exactly,” Dr. Fontijn said. “It is possible that the magma is fairly happy sitting down there for a while. We don’t know if it will come straight away to the surface.”
Competent volcano monitoring is credited with saving thousands of lives in this part of the Pacific region, known as the Ring of Fire for its intense volcanic activity. The Pinatubo eruption, on the Philippines island of Luzon in 1991, was one of the largest eruptions of the 20th century, but deaths numbered in the hundreds, thanks to what authorities said were stringent monitoring and an effective evacuation plan.
Tambora, 1815: A volcano erupted on the eastern Indonesian island of Sumbawa, creating a massive tsunami that killed nearly 100,000 people. Ash from the eruption led to a gloomy summer in Europe, inspiring Mary Shelley to begin writing Frankenstein.
Krakatoa, 1883: A massive series of eruptions destroyed the small island of Krakatoa, just west of Java, and turned European sunsets bright red for months, lowering global temperatures by more than 2 degrees Fahrenheit the next year. Scholars have credited red sunsets as inspiration for the reddish sky of Edvard Munch’s painting “The Scream.”
Indonesia’s national volcano monitor has said an eruption may be imminent but that the current seismic activity could continue for weeks. It is difficult to estimate timing, in part because modern equipment wasn’t available to measure the last eruption, so scientists don’t know how current activity compares with the lead-up to eruptions past.
“Managing the crisis at Agung is a new thing,” said Dr. Devy Syahbana of Indonesia’s Center for Volcanology and Geological Hazard Mitigation. “There was no instrumental documentation before the eruption of Agung in 1963.”
When Agung began belching steam and sulfuric gas a week ago, prompting the evacuation of more than 130,000 Balinese, the island’s volcanologists had already begun detecting tremors beneath the base of the volcano.
Recent seismographic measurements indicate earthquakes are rising closer to the base of the volcano, suggesting that red-hot magma is coursing up through the mountain. Satellite data tells a similar story, showing new thermal areas in the summit crater, again implying that magma is pushing upward.
Meanwhile, tiltmeter data, which measures deformation in the volcano’s shape, suggest the mountain is inflating with magma. As magma and sulfuric gases push toward the peak, pressure builds, eventually leading to an explosion.
Scientists say an eruption of Agung would lead to pyroclastic flows that would kill anyone in their path and devastate farmland, as happened in 1963. Such flows—made up of gas, ash and rock—are produced by composite volcanos like Agung.
Bali on High Alert for Possible Mount Agung Volcano Eruption
More than 100,000 people have evacuated the Indonesian tourist island
A woman and child sit in a tent at an evacuation center for people living near Mount Agung, a volcano on the highest alert level, outside a sports arena in Klungkung, on the resort island of Bali, Indonesia.
DARREN WHITESIDE/REUTERS
The most recent official notice warns that the magnitude of earthquakes beneath the volcano is increasing and that “the probability of an eruption is higher than the probability of no eruption.”
Independent experts, less cautious, say that an eruption is imminent. “It’s much more likely to keep going now then to stop,” said Richard Arculus, an emeritus professor of geology at Australian National University.
But scientists say they lack the tools to predict precisely when an eruption will occur, even in situations like the current one, where they believe an eruption is likely.
Karen Fontijn,a physical volcanologist and postdoctoral research associate at Oxford University, researched Agung’s eruption patterns over the past 5,000 years by using carbon dating to analyze underground ash layers. Her research suggests that Mount Agung’s eruptions tend to be of a fairly consistent scale. But the historical data don’t indicate how long the lead-up to an eruption will be.
Earlier
Indonesia's disaster agency said an eruption appears imminent at Mount Agnug after a half-century of calm. Photo: Getty Images
Because of the uncertainty about timing, some Balinese farmers are entering the eruption zone during the day to tend to their land, according to Hevy Umbara, a geologist volunteering near Mount Agung to warn locals of the dangers of returning to their fields.
“I worry farmers will become victims,” he said. “We need a solution so that farmers don’t enter the danger zones.”
Farmers may have to wait a long time to return to their fields.
“We really can’t tell when it will erupt exactly,” Dr. Fontijn said. “It is possible that the magma is fairly happy sitting down there for a while. We don’t know if it will come straight away to the surface.”
Competent volcano monitoring is credited with saving thousands of lives in this part of the Pacific region, known as the Ring of Fire for its intense volcanic activity. The Pinatubo eruption, on the Philippines island of Luzon in 1991, was one of the largest eruptions of the 20th century, but deaths numbered in the hundreds, thanks to what authorities said were stringent monitoring and an effective evacuation plan.
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