Yellowstone volcano: How 900 ‘intense’ earthquakes left USGS nervous – ‘Not good!’

“These are seismograms from the 27th, they’re both near Yellowstone Lake, each line represents 15 minutes.

“Each one of these little lines represents a separate earthquake, they get bigger, there’s a two, a three-and-a-half (magnitude) and the largest was a four.

“Very intense earthquake activity going on, about 900 located earthquakes in the end from this swarm.”

In 1959, Yellowstone National Park faced one of its most shocking events – the Hebgen Lake earthquake.

The natural disaster caused massive damage, including 28 fatalities and a considerable £9million in repairs to highways and timbers.