Yellowstone National Park is fighting viral rumours of an impending, cataclysmic eruption of a mega volcano slumbering at the western US preserve known for its geothermal features.
Volcanologists said reams of geological data had given them a deep understanding of the Yellowstone Caldera - and all signs pointed to calm.
Over the past several weeks, the internet has been abuzz with speculation over worrying signs suggesting an explosive awakening for the so-called supervolcano, whose last catastrophic eruption was 640,000 years ago.
That eruption covered a good portion of North America in ash several centimetres thick, and had a long-lasting impact on the Earth's climate.
A video showing a herd of bison fleeing the Wyoming park went viral. And several days later, a 4.8-magnitude earthquake, the strongest in three decades, fed the rumour mill still further.
But Yellowstone spokesman Al Nash said there was nothing out of the ordinary in the animals' behaviour.
"We do have bison, elk and other animals that have moved out of the park recently," he said.
"They tend to migrate at this time to lower elevations, where they think they can get food, and then they come back."
As for the quake: "It was the strongest in 30 years, but it was not that strong," said Peter Cervelli, a volcano expert at the US Geological Survey.
And such jolts are not exactly rare, with an estimated 1,000 to 3,000 quakes a year at the park.
He rebuffed rumours that a big eruption was coming and predicted there would not be another major eruption "for the next tens of thousand of years".
His confidence was based in part on the many instruments, including dozens of GPS receivers and seismometers, that monitor activity in the volcano whose giant magma chamber measures 88 kilometres long, 29 kilometres wide and 14 kilometres deep.
Around a dozen experts are also permanently stationed at Yellowstone.
Geologist Ilya Bindeman was equally confident, based on his isotopic analysis of the volcanic rocks at Yellowstone.
"I don't think another major eruption is going to happen anytime soon - at least not for another one to two million years."
Such an eruption would destroy everything within a radius of several hundred kilometres and would cover North America in ash, putting an end to agriculture and cooling the Earth's climate for at least 10 years.
The last time the Earth experienced such an eruption was in Indonesia, 70,000 years ago.