More than a dozen earthquakes struck an area near Yellowstone National Park within 24 hours.
The US Geological Survey (USGS), who monitor seismic activity across the US, recorded the latest earthquake swarm to hit the area on Friday.
The USGS data recorded 20 significant earthquakes with 1.5 magnitudes or higher on that day, amongst dozens more smaller tremors.
The largest earthquake was recorded at 3.1 magnitude and struck at a depth of 6 miles, at 11:39am on 29 May.
That came amongst some 16 earthquakes and smaller tremors which struck an area near West Yellowstone, Montana, on 29 May, between 10:50am and 11:50am.
According to the USGS’s own earthquake map, around 70 earthquakes and tremors were recorded on Friday alone.
The tremors struck 15 miles outside the Yellowstone National Park, with depths between 1.4 miles and 6 miles below ground.
It comes after 43 earthquakes with magnitudes over 1.5 have hit the same area over the past 30 days, according to Earthquake Track.
The national park’s website says that so-called earthquake swarms are not unusual at Yellowstone, and account for about 50 per cent of all tremors in the area.
The park also states that most earthquakes are magnitude 2 or below and so they are not felt by anyone.
Yellowstone is among the most seismically active places in the US, and sees around 700 to 3,000 earthquakes every year.
On Monday, the park’s Montana entrances were reopened to visitors after the state removed 14-day quarantine rules amid the Covid-19 pandemic.
Yellowstone’s Wyoming and Idaho entrances have also reopened to day visitors.
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