The Secrets of Yellowstone Revealed

Get ready for an auditory adventure like no other! Nestled beneath the surface of Yellowstone National Park is a fascinating phenomenon that's not only crucial for monitoring volcanic activity but also helps us detect explosive hydrothermal events—thanks to an innovative technology called infrasound.

What is Infrasound?

Infrasound refers to those low-frequency sounds that lurk below the human hearing threshold, specifically between 0.1 and 20 Hz. While these sounds might be inaudible to our ears, they play a critical role in monitoring natural processes in the Earth's atmosphere. The remarkable thing about infrasound is that it travels efficiently through the air, making it capable of covering vast distances while losing little energy along the way.

Tracking Explosions Like Never Before

Infrasound's ability to carry sound waves long distances is already harnessed to identify nuclear tests. But the same technology offers an unprecedented advantage: it’s also brilliant for monitoring volcanic eruptions! For instance, just a few infrasound stations in Alaska keep watch over the entire Aleutian island chain—stretching a whopping 1,100 miles (1,800 kilometers)!

How It Works: The Triangular Setup

To get the most accurate readings, infrasound monitoring relies on an array of at least three sensors arranged in a triangular formation. This configuration allows scientists to pinpoint the direction of incoming sound waves, as the slower speed of infrasound means they arrive at the sensors at different times—a perfect setup for triangulation!

A New Era of Monitoring in Yellowstone

Until recently, Yellowstone's infrasound monitoring was limited to short-term setups that studied specific geysers. However, as of September 2023, the park now boasts its first continuous, permanent infrasound array with three sensors located in the Norris Geyser Basin. This game-changing station has already begun to track explosive geyser activity, continuously detecting infrasound signals for hours after eruptions.

The Boom that Rocked Yellowstone

Mark your calendars: on April 15, 2024, a powerful 'boom' was detected by this station, corresponding to a small hydrothermal explosion near Porcelain Basin. Despite being unwitnessed, this explosion left a striking crater about 10 feet wide and disturbed the ground around it. This event proves that infrasound can be a vital tool in spotting hydrothermal explosions that might otherwise go unnoticed.

Need for More Stations

However, not all is covered by a single station. For instance, a significant hydrothermal explosion at Biscuit Basin on July 23, 2024, located 18 miles away from Norris, went unheard by the infrasound sensors. This raises a crucial point—expanding the network of infrasound stations across Yellowstone is essential for comprehensive monitoring of its vast and varied geyser basins.

Infrasound and Celestial Events

Interestingly, infrasound doesn’t just track geological events. On May 3, 2025, a bright fireball illuminated the sky over multiple U.S. states, and residents in Yellowstone reported a loud booming sound as it exploded in the atmosphere. Unsurprisingly, the Norris station captured this extraordinary moment as well!

Listening to the Unhearable

Although these sounds are below what our ears can hear, scientists have a trick up their sleeve: they can 'sonify' infrasound data, converting it into audible sound. This means even if you missed the May 3 fireball, you can still 'hear' the explosion by listening to this fascinating data!

Looking Ahead: Expanding the Infrasound Network

With plans to deploy more infrasound stations in the coming years, the Yellowstone Volcano Observatory is poised to enhance its monitoring efforts even further. Keep your ears tuned for more exciting discoveries as we continue to explore the hidden sounds of this breathtaking national park!