There are few countries in the world as prepared for volcanic eruptions as Japan. Nestled on the ring of fire, it’s home to a plethora of them, and a new Scientific Reports study reveals that one in particular is almost certainly due to erupt within the next 28 years.
Sakurajima, nestled on the mainland island of Kyushu, is constantly active, and is somewhat safe to be around. However, it also has a history of violent blasts that can lead to fatal outcomes, with the most recent disaster taking place in 1914. In what turned out to be the largest eruption in 20th-century Japan, the surrounding landscape was irreversibly scorched and 58 people lost their lives.
With this in mind, a team of geoscientists decided to attempt a supremely difficult task – predict when the next eruption would be to within a few years.
First, they used pioneering techniques designed to measure ground deformation at the surface to generate cutting-edge 3D models of the underlying magma source, which is fed from the nearby Aira caldera. Their data revealed that 14 million cubic meters (494 million cubic feet) of magma is being pumped into the shallow crust beneath Sakurajima every single year – roughly 13.4 Empire State Building’s worth.
Of course, some of this escapes during the daily local explosions at the summit, but not much. Crucially, the team calculated that the magma is being supplied to the volcano faster than it can erupt.
During the 1914 eruption, 1.5 cubic kilometers (0.36 cubic miles) of volcanic debris was unleashed. Based on the current magma supply rate, this means that a repeat of 1914 would take 130 years, which suggests that by about 2044, Sakurajima will showcase its destructive skills yet again.
“If it follows the pattern of the 1914 eruption, the paroxysm would start with a large Plinian explosion featuring a huge column of ash,” lead author Dr James Hickey, a volcanologist at the University of Exeter, told IFLScience. A prolonged lava flow and superheated pyroclastic flows are also likely to appear.
Any major signs of trouble, then, would require a full evacuation of the surroundings. Fortunately, by coming up with a rough timeframe in which Sakurajima may erupt in this manner, this study has given the local government a chance to plan ahead – and perhaps save plenty of lives as a result.
Image in text: The 1914 eruption of Sakurajima. Wikimedia Commons/Public Domain
Sakurajima is Japan’s most active volcano. Since 1955, slugs of gas have forced their way up through gloopy, broiling magma, generating almost daily blasts at the summit, and the occasional stunning fire fountain. Every year or so, a more explosive outburst occurs, accompanied by ominous ash clouds and even volcanic lightning.
However, these are rarely dangerous, if at all. The infrequent lava bomb may land on a resident street, and the ash may cause some breathing problems to those of an advanced age, but generally speaking, the predictability of this volcano renders it somewhat safe to live around – and more than 605,000 do, mostly within the nearby city of Kagoshima.
But 1914’s events hint that trouble is literally brewing. “Sakurajima” means “cherry blossom island”, but today it’s a peninsula. At the start of the First World War, the volcano blew its top so violently and effusively that the volcanic debris caused a land bridge to form between the island and the mainland.
Scores of people perished back then, but there are plenty more living in the shadow of the volcano these days at risk from such an event. Indubitably, an eruption as bad as the 1914 event today would be a disaster, but this study has forewarned the region – and forewarned is forearmed.
Sakurajima (center) erupting in 2013, as seen from space. NASA