More than 200 earthquakes have rocked Yellowstone National Park in recent days, home to the largest super volcano in the USA.
The present swarm began on February 8 but activity “increased markedly” a few days later on February 15, said the United States Geological Survey (USGS).
On Sunday, a 3.1 magnitude earthquake was recorded 12km north-east of West Yellowstone, while the largest activity inside the park reached 2.9 magnitude.
What will happen if Yellowstone explodes?
A giant eruption at Yellowstone National Park could impact the world’s global climate for years afterwards – even decades – according to the USGS.
On its website, it says: “Such a giant eruption would have regional effects such as falling ash and short-term (years to decades) changes to global climate.
“The surrounding states of Montana, Idaho, and Wyoming would be affected, as well as other places in the United States and the world.
“Such eruptions usually form calderas, broad volcanic depressions created as the ground surface collapses as a result of withdrawal of partially molten rock (magma) below.
“Fortunately, the chances of this sort of eruption at Yellowstone are exceedingly small in the next few thousands of years.”
Yellowstone is known to have erupted violently several times in the last two million years and the geology of the landscape, including lava flows and rock formations, is formed from these huge explosions.
The Yellowstone Plateau volcanic field has spanned three volcanic cycles during this time and includes two of the world’s largest-known eruptions, according to USGS.
The 2450 km3 Huckleberry Ridge Tuff erupted about 2.1 million years ago, creating the current caldera – a 75km basin-shaped volcano depression – after large volcano deposits formed.
It now stands 2,805 metres tall and lava last erupted from there 70,000 years ago.
Will Yellowstone erupt again?
Major eruptions are incredibly rare. USGS said Yellowstone’s current earthquake swarm account for more than more than 50 percent of the seismic activity at Yellowstone, and no volcanic activity has occurred from any past such events”.
But Brian Wilcox, an ex-member of NASA Advisory Council on Planetary Defence, has previously warned that the supervolcano threat posts a bigger risk to life than an asteroid hurtling to earth.
In an interview last year with the BBC, he said: “Yellowstone explodes roughly every 600,000 years, and it is about 600,000 years since it last exploded, which should cause us to sit up and take notice.”