Naturalist Notes

Tuesday July 23rd, 2024 there was a geothermal explosion in Yellowstone. The explosion occured at the Black Diamond Pool of the Biscuit Basin geothermal area on a typical summer morning whilst visitors strolled the boardwalks adjacent the offending pool and others like it. In a video linked, geologist researcher Jamie Farrell, stated that there was a 2009 geothermal explosion in Biscuit Basin.

The explosion sent rock, mud, steam and boiling water hundreds of feet in the air. Rocks the size of softballs were hurtled 100 feet away. It was even powerful enough to send a rock three feet in diameter weighing hundreds of pounds skyward. Miraculously, no bystanders strolling the boardwalk that passes within 20 feet of the pool were hurt. The same could not be said for the boardwalk, which is now closed for the season due to the damage.

Does this explosive event herald the eruption of the Yellowstone Supervolcano? Could this spell the end for civilization as we know it? No, not anytime soon geologists tell us. Hydrothermal explosions like this one actually occur relatively often within Yellowstone atop the caldera of the supervolcano where most of the geyser basins like Biscuit Basin sit. (Other famous geothermal features like the Grand Prismatic, Old Faithful, and Morning Glory Pool also sit atop Yellowstone’s gargantuan Caldera for reference). For instance, earlier this year, a similar hydrothermal explosion occurred at a the Norris Geyser Basin about 25 miles away.

This has been a typical year in that regard, with a couple of noteworthy hydrothermal explosions having already occurred. That explosion wasn’t wasn’t captured on video like the Black Diamond Explosion on the 23rd. Just like the average earthquake count detected within the park is 2500 annually, hydrothermal explosions like this which occur with some regularity, but without epic video captured of the event from multiple angles by steady-handed onlookers. All are just a part of life for this dormant but still active volcano which is the geothermal driver of all of this activity.

Not long after Yellowstone’s official exploration by the US government and it’s establishment as the country’s, indeed the world’s first, national park yellowstone has had multiple geothermal explosions of note.

The first of which was the explosion of the Mud Volcano. Today you can visit a geothermal area named for that very feature. The Mud Volcano, however, no longer erupts. It is still quite an active geothermal feature with noteably violent churning of acid mud the roils and boils around the clock. When Washburn-Doane Expedition of 1870 first documented it erupting from a cone in such violent fashion that it could be heard from a half mile away. But by the time the Hayden Expedition arrived to survey the area a year later the Mud Volcano had blown itself up in a hydrothermal explosion and the cone from which it had erupted was now a crater with a mud pot in the bottom of it that we see today.

Another hydrothermal explosion blurs the lines between geyser eruptions and a more anomolous event like the July 23rd event at Black Diamond Pool. Located several miles from the Black Diamond Pool and Biscuit Basin at the Midway Geyser Basin sits the Excelsior Geyser, which is now a dormant. The entire hot spring and geyser sits within a ‘blast crater’ that constantly flows out into the Firehole River at a rate of 4-4.5 thousand gallons per minute of nearly boiling water. You pass by this while walking the boardwalk en route to the Grand Prismatic Hot Spring. During the 1800’s however, many of its eruptions were documented, and even photographed in 1888. They were, as described by then park superintendant Philetus Norris as:

“…simply incredible, elevating to heights of 100 to 300 feet, sufficient water to render the Fire Hole River, nearly 100 yards wide, [into] a foaming torrent of steaming hot water, and hurling rocks of from one to 100 pounds in weight, like those from an exploded mine, over surrounding acres.”

Those eruptions seen by early park officials and visitors that ejected rocks were violent enough to be described as hydrothermal explosions, but the structure of the ‘crater’ implies and even more violent eruption in Excelsior’s past.

Thus, Yellowstone is an extreme dynamic place from a geologic perspective. Lava that sits roughly two miles below the surface within the caldera is the driving energetic force for these events. Change is, indeed, it’s only constant. Though in its dormant state between eruptions – the last being roughly 640,000 years ago – Yellowstone will continue to see these hydrothermal explosions as subterrainean water bores new cracks into rock and finds new routes to the surface (sometimes violently).