Yellowstone Supervolcano: What’s causing the unprecedented earthquake swarm? 878 quakes in two weeks!
YELLOWSTONE SUPERVOLCANO EARTHQUAKE SWARM REACHES 878 EVENTS IN JUST TWO WEEKS
BY HANNAH OSBORNE
Updated | Over 800 earthquakes have now been recorded at Yellowstone supervolcano over the last two weeks, with the ongoing swarm taking place on the western edge of the National Park.
But there is virtually no risk of the volcano erupting, the United States Geological Survey (USGS) currently lists the volcano alert level as normal and the aviation color, which lists the potential risk to fights, is at green.
The current earthquake swarm began on June 12. A week later, the USGS put out a statement to say that 464 earthquakes had been recorded, with the largest being magnitude 4.4 “This is the highest number of earthquakes at Yellowstone within a single week in the past five years,” it said.
At the time, a spokesperson for the USGS told Newsweek activity appeared to be “slowly winding down,” adding that “no other geological activity has been detected.”
However, in a newly released statement about the ongoing swarm, seismologists from the University of Utah said 878 events have now been recorded at Yellowstone National Park.
The University of Utah is part of the Yellowstone Volcano Observatory (YVO), which provides long-term monitoring of earthquake and volcanic activity in and around Yellowstone National Park. Jamie Farrell, Research Professor at the university, said that as of June 26, 878 events had been recorded as part of the ongoing swarm.
“The swarm consists of one earthquake in the magnitude 4 range, five earthquakes in the magnitude 3 range, 68 earthquakes in the magnitude 2 range, 277 earthquakes in the magnitude 1 range, 508 earthquakes in the magnitude 0 range, and 19 earthquakes with magnitudes of less than zero,” the latest report said.
An earthquake with a magnitude less than zero is a very small event that can only be detected with the extremely sensitive instruments used in earthquake monitoring.
While increased seismic activity can signal a volcano is about to erupt, the latest earthquake swarm is no cause for concern. Jacob Lowenstern, the scientists in charge of the YVO at the USGS, tells Newsweek the swarm has slowed down considerably, and that larger swarms have been recorded in the past.
“The swarm in 2010 on the Madison Plateau lasted at least three weeks. In 1985, there was one that lasted several months,” he says. “Yellowstone has had dozens of these sorts of earthquake swarms in the last 150 years it’s been visited. The last volcanic eruption within the caldera was 70,000 years ago. For magma to reach the surface, a new vent needs to be created, which requires a lot of intense geological activity.
“The volcano alert level remains at green. As outlined in our response plan, USGS Circular 1351, we would need to see considerably more and larger earthquakes, combined with contemporaneous ground deformation, steam explosions, and changes in gas and heat discharge prior to moving the alert level. None of that has occurred.”
The USGS says the current risk of an eruption at Yellowstone is one in 730,000. Furthermore, if it were to erupt, the eruption produced would probably be fairly inconsequential. Lowenstern explains: “If Yellowstone erupts, it’s most likely to be a lava flow, as occurred in nearly all the 80 eruptions since the last ‘supereruption’ 640,000 years ago. A lava flow would be a big deal at Yellowstone, but would have very little regional or continental effect.”
Farrell also says the earthquake activity is nothing to worry about: “This is definitely not the biggest swarm ever recorded,” he says. “The largest swarm ever recorded in Yellowstone occurred in October of 1985 and lasted for 3 months and had over 3,000 located earthquakes in it. In January of 2010 there was a swarm that had over 2,000 located events in it that lasted for about a month.
“Swarms in Yellowstone are a common occurrence. On average, Yellowstone sees around 1,500-2,000 earthquakes per year. Of those, 40 to 50 percent occur as part of earthquake swarms. This swarm is larger than the average swarm we record but this is a normal thing to happen in Yellowstone (and other volcanic regions throughout the world).”
He says they are not seeing an “volcanic signatures” that would indicate an eruption could take place. “This looks to be a ‘tectonic’ swarm in that these earthquakes are due to slip on small faults/fractures in the crust. There doesn’t look to be any evidence at this point that these earthquakes are related to the movement of magma in the subsurface.
“Having said that, we will continue to monitor this swarm just in case we start seeing those things.
“When a volcano starts ‘acting up’ prior to an eruption, one of the typical signs is increased seismicity. However, it is usually just one of the signs of an impending eruption. Other signs include, large changes in surface deformation, changes to the hydrothermal system and changes in gas output. We monitor for all these things at Yellowstone. Typically if we see just one of these things, it doesn’t necessarily mean there is an eruption coming. If we start to see changes in all these things, then a red flag may be raised.”
This story has been updated to include quotes from Jacob Lowenstern and Jamie Farrell.