Scientists predict there is a one in six chance of a massive volcanic eruption this century, but what impacts would such an event cause?
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Around 1,500 active volcanoes are scattered across the planet, from the rim of the Pacific Ocean to the peaks of the Chilean Andes. Nearly 800 million people live within 60 miles of one. But what would happen if a volcano erupted on a catastrophic scale? And could it really happen today?
Where could a massive eruption occur?
The next massive eruption could happen anywhere on Earth.
Of course, there are areas that are of particular interest to scientists, including Indonesia – a particularly active volcanic region – and Yellowstone in the western US, which hasn’t experienced a huge eruption for 640,000 years.
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Yellowstone has often made headlines as the purported site of the next supereruption, having erupted three times in the last 2.1 million years. However, scientists say a massive eruption like its last one is an unlikely scenario. Officials say the most likely future activities are hydrothermal explosions (eruptions of steam and hot water) and lava flows.
Bolivia’s Uturuncu volcano has also been a site of much interest – since the 1960s, an area of more than 1,000 square kilometres centred on the volcano has been uplifting. In addition, Chile’s Laguna del Maule – which has been the location of huge caldera-forming eruptions in the past – has been swelling at a rate of almost one foot per year across the last two decades. So, if a super-eruption were to occur, these two sites may be of particular interest to scientists.
Are these eruptions more likely today?
Climate change is known to impact volcanic systems. Melting ice can lead to more eruptions, as the resulting meltwater decreases pressure and allows magma to rise faster. Extreme rainfall – driven by climate change – can also enter the ground and mix with magma to trigger eruptions.
But overall, volcanic eruptions are not becoming more likely, according to the Smithsonian Institution’s Global Volcanism Programme. While modern connectivity means we might hear about eruptions more, the actual frequency of gigantic eruptions has not increased.
Working out exactly when volcanoes will erupt is tricky, but scientists are becoming much more attuned to understanding when they will happen. That’s because volcanoes give off signals in the hours – and sometimes years – before they erupt. Such signals include changes in gases, earthquakes, and changes in the ground, which can be detected using satellites and other equipment.
What would happen if a massive eruption occurred?
When volcanoes erupt, they release lava, ash and gases, including planet-warming carbon dioxide. Volcanic ash can devastate crops, contaminate water supplies and even cause buildings to collapse under its weight. Freshly fallen dry ash can weigh up to 20 times as much as snow.
But some eruptions can significantly alter the planet’s climate. Scientists are particularly interested in sulphur dioxide, which can be blasted high into the stratosphere during a major eruption.
In the stratosphere, sulphur dioxide can form tiny aerosol particles that scatter sunlight, reflecting it into space and cooling the planet below. One such example was the 1991 Mount Pinatubo eruption in the Philippines, which ejected roughly 15 million tonnes of sulphur dioxide into the stratosphere. Such vast quantities of the gas cooled the world by around 0.5 degrees Celsius for several years after.
Prior to this, the massive 1815 eruption of Tambora in Indonesia had a larger effect on the planet. The year that followed was known as the ‘year without summer’, named as such due to crop failure, famine and unusual weather patterns.
In addition, a huge eruption in Samalas in Indonesia in 1257 is thought to have helped trigger a ‘Little Ice Age’, a cold period that lasted hundreds of years. And an eruption in Okmok in Alaska back in 43BC could have cooled parts of southern Europe and northern Africa by up to seven degrees Celsius. So, if a massive eruption were to occur, it is almost certain that temperatures would be affected here on Earth.
Massive eruptions are also believed to affect rainfall and can dry monsoon systems in Africa and Asia.
Recent analysis by Lloyd’s has shown that such eruptions could impact several breadbaskets at once – such as the US, China and Russia – and have a sizeable effect on food security, leading to political tensions and even war.
If a supervolcano were to erupt – for example, Yellowstone – the impacts would be even greater. The surrounding states of Wyoming, Idaho and Montana would be directly impacted by huge avalanches of volcanic ash, gases and rocks, moving at more than 300 kilometres per hour and travelling for more than 100 kilometres. The whole continent of North America would be affected if Yellowstone were to erupt, with the surrounding 800 kilometres likely covered in a thick blanket of ash.
