Earthquakes May Trigger Yellowstone’s Steamboat Geyser: NPR

Steamboat is the tallest active geyser in the world, but unlike Old Faithful, its eruptions are completely unpredictable.

Now, a new analysis suggests that at least one recent steamship explosion was caused by a small earthquake.

The 3.9 earthquake occurred in September 2022 and its epicenter was about 7 miles from Steamboat, which is in the Norris Geyser Basin of Yellowstone National Park in Wyoming.

“Somebody ran out there right after the earthquake to see if Steamboat was doing anything, and right after the earthquake, it looked normal,” Mara Reed recalled., a graduate student at the University of California, Berkeley.

However, about eight hours later – ah!

The steamship had one of its major explosions, which can send water hundreds of feet into the air.

Reed and some colleagues wondered if the two events were connected and did an analysis that was just published in the journal Volcanic.

“We definitely think it’s credible. I would argue that’s probably what happened,” Reed says.

The report comes just days after Steamboat had another explosion that closely followed an earthquake. This was a 4.1 tremor with an epicenter about 100 miles away from the geyser.

“I think it’s really intriguing. And it seems entirely feasible to me that a geyser that’s close to erupting could be pushed over the edge by some seismic tremors,” says Michael Poland of the US Geological Survey, which runs the Yellowstone Volcano Observatory.

“But it’s really, really hard to prove beyond a reasonable doubt,” he says, “because it’s always possible that it was just a coincidence.”

Geyser Rockstar

The world only has about a thousand geysers, and about half are in Yellowstone.

Besides being interesting in their own right, they are good analogs for volcanoes. About a tenth of the world’s population lives within the potential range of volcanic hazards, so researchers are keen to understand what might cause one.

“We’ve known for a long time that earthquakes trigger volcanic eruptions, but understanding when and why remain open questions,” says Michael Manga of the University of California, Berkeley.

“Geysers provide another opportunity to study how stress affects fluids,” he notes, because the underlying physics is similar.

In the world of geysers, Steamboat is something of a rock star.

It’s huge, and it can also inexplicably sleep for years. When it wakes up and becomes active, eruptions can occur every few days. Or, they can be separated by weeks to months.

“The steamship is special. “The steamboat is now king,” says Poland. “There are these eruptions that will go up maybe 400 feet, and part of the mystique, maybe, is that it’s not predictable.”

Scientists have installed several seismometers near Steamboat, and these instruments can pick up tiny tremors in the ground caused by the hot, boiling water.

“Imagine if you see a pot of boiling water on the stove, that’s pretty powerful,” Poland says.

After the 2022 earthquake, an instrument near Steamboat recorded a change in the intensity of this hydrothermal rumble, Reed says.

That means the earthquake may have changed the flow of fluids underground and sent more hot water toward Steamboat.

“So we know that the hydrothermal system at that point near the seismometer was altered,” she says. “That doesn’t necessarily prove that it changed in a way that affected Steamboat, but it’s plausible that it did, based on what we know about the geology, the area, and the kind of precise types of seismic signals that we were seeing.”

The research team also did a statistical analysis that showed there was a very low probability that Steamboat had exploded that day just by chance.

Larger earthquakes

Poland says that for about two months before that big explosion, the Steamship looked like it was about to leave.

He had experienced a series of small explosions that sent the water splashing only 10 feet or so over his chute.

The same was true this month on October 7, when a 4.1 earthquake struck near Dillon, Montana, about 100 miles from Steamboat.

A few hours later, Steamboat had a huge explosion.

Perhaps, in both cases, Steamboat was close to exploding and the earthquake just gave it a boost, Poland says.

“If so, in both cases, why was there a delay of several hours between the earthquake and the explosion?” he asks.

The steamship has experienced several major regional earthquakes without exploding. For example, it did not erupt after the 7.3 Hebgen Lake earthquake that affected many other Yellowstone geysers.

Reed notes that large earthquakes are likely to open more new cracks and fluid paths underground, but when that earthquake occurred in 1959, Steamboat was not in an active phase.

“Maybe it just needs to get ready to explode,” Reed says.

The same seems to be true of volcanoes, she says.

“Maybe the internal state of the volcano is very important,” says Reed. “The volcano must already be primed to erupt for an earthquake to occur and just give it a little extra push.”