But Mike Poland, a research geophysicist with the Cascades Volcano Observatory, has said while the region remains an “incredibly dynamic place” with high levels of volcanic activity, there was no reason to think it was behaving in an abnormal way which could indicate a disastrous eruption was likely.
Mr Poland was one of a number of scientists who addressed a conference call press conference to discuss the unveiling of the 2018 Update to the United States Geological Survey (USGS) National Volcanic Threat Assessment, which ranks 161 volcanoes throughout the country in terms of the risk they would pose in the event of an eruption.
Yellowstone, located in Yellowstone National Park, which straddles three US states, Wyoming, Idaho and Montana, is ranked 21st on the list, with an overall threat score of 115th, and is rated in the “high risk” group. Hawaii’s Kilauea is 1st, with a score of 263.
The increased number of eruptions at the Steamboat Geyser have taken some scientists by surprise, and Mr Poland said: “We’ve been studying the system for just this tiny little speck of this long existence of this system.
It’s been around generating heat for two million years and whether or not it is tapped out is difficult to say.
“Certainly I wouldn’t interpret anything that has happened over the last few years as something reflective of a system that’s as long lived as Yellowstone.
“But I do think that there is something to this idea that there have been some hydrological changes and that maybe that is why we are seeing for example Steamboat Geyser, which typically erupts once every few years, has gone up quite a bit.”
The geyser has erupted 24 times this year, but Mr Poland said: “That is not unprecedented – it has gone of dozens of times a year in the 1980s and the 1960s so it is not like this is completely new.
“But there is something to be said for all the precipitation that has fallen in that particular part of the Rocky Mountains in the last few year.
“Perhaps there is more water available to be heated by the hot rock and then generate these eruptions.”
Mr Poland said little was known about many of the geysers at Yellowstone because they were difficult to study and highly unpredictable.
He added: “Most geysers are not like Old Faithful – they don’t erupt on schedule.
“And so most of the studies of geysers tend to focus on places like Old Faithful, where you do know it is going to erupt, because you would not necessarily study something which would be dormant during the time period that you were looking at it.
“So we have a lot of knowledge about places like Old Faithful, which behave in some predictable way, but that is not the most common type of geyser.
“We don’t tend to know so much about these more intermittent ones, and that’s what we hope to learn more about and maybe understand how and why they come back to life and whether or not the hydrology of this system is maybe responding to changes in precipitation over the last few years for example.”
In terms of the area as a whole, he added: “Yellowstone is an incredibly dynamic place. It is always changing. Different geysers are erupting.
“Dormant springs comes to life or cool down.
“The ground is always moving up and down.
“There are also earthquake swarms that are very common – typically you get 2000 earthquakes a year in the Yellowstone region on average.
“In that sense all these things are changing – there’s always something going on.
“But that’s what defines Yellowstone so there is nothing particularly abnormal in that respect that has happened since Yellowstone has been monitored as a volcano.
“Last year we did have the second-largest seismic swarm since monitoring really began in the 1970s but that is not particularly noteworthy.
“There were 2,400 quakes or so that occurred in a three or four-month period but that’s the second largest not the largest.
“We don’t really have any indication that Yellowstone is doing anything abnormal.
“It’s moving up and down, there’s lots of earthquakes, geysers are going off and that’s exactly what it ought to be doing.”