When it comes to studying the inner workings of Earth, Yellowstone National Park may just be a geologist's dream. The park spans about 3,472 square miles and is home to dense forests, a variety of wildlife, and the Yellowstone Caldera.
The caldera is brimming with various types of magmatic, hydrothermal, and seismic activity, making it the ideal place for geologists to get a little more up close and personal with this volcano. According to the United States Geological Survey (USGS), the park experiences anywhere between 1,500 and 2,500 earthquakes per year and experiences a variety of hydrothermal activity daily.
From this activity, researchers have mapped how magma flows underground, causing the surface to shift, and how seismic activity can shake up life in the park. But what happens when these magmatic and seismic events happen at the same time and in the same place?
Read More: A Mysterious Ground Shift Returns to Yellowstone, and Advanced Tech Is Helping to Monitor It
Types of Magmatic Activity and Seismicity in Yellowstone
Besides Yellowstone’s hydrothermal features, like Old Faithful and the Grand Prismatic Hot Spring, the park also sees magmatic activity, like deformation. Deformation occurs when subterranean magma or other fluids begin shifting, causing the ground to uplift or subside. Essentially, the fluids cause the ground to swell or contract.
When it comes to seismic activity, or seismicity, the park is obviously no stranger to it. According to the USGS, the largest earthquake to occur just outside the park was in 1959 and measured at magnitude 7.3. However, most earthquakes in or near the park are too small to feel and are only detected by the USGS's monitoring equipment. Earthquakes in the park, according to the USGS, are typically brittle-failure events, meaning they’re caused by rocks breaking under crustal pressure.
Yellowstone’s Magma and Earthquake Connection
While it may seem like magmatic activity and seismicity would often occur together, according to Michael Poland, the Scientist-in-Charge at the Yellowstone Volcano Observatory, that’s not the case.
“The connections between deformation and seismicity are usually for specific episodes [and/or] incidences of activity,” Poland says. “But there are also broader long-term patterns where there are no associations […] and the [approximately] 1500-2500 earthquakes that occur per year in Yellowstone are widely distributed and more a result of water interacting with existing faults.”
Though these events are rare, the USGS has tracked a few instances of deformation and seismicity. For example, in 2008, researchers tracked a swarm of earthquakes over 10 days. They began beneath Yellowstone Lake and migrated north. During that time, the earthquake caused the ground near an observation station to shift about ⅓ of an inch to the west.
From this data, researchers suggest that the earthquakes were likely caused by pressurized fluids that came from the upper-crustal magma reservoir. As the rocks cracked during the earthquakes, fluid pushed through the cracks, causing deformation.
What Do These Rare Events Mean For Yellowstone?
While these events have occurred in the past, just recently, the USGS reported on the return of the Norris Uplift Anomaly, a deformation event caused by magma or other fluids shifting underground. The uplifting and subsisting is so minimal that it can only be detected with specialized equipment. However, in July 2025, data shows that the anomaly was back.
According to the USGS, around this same time and in the same location, there was also an earthquake swarm, so it’s possible that this anomaly may also be part of a rare crossover event, though more information is still needed before any conclusions can be drawn.
While geologists continue to study these rare and intriguing events, according to Poland, these events are very natural, and visitors can still enjoy the park. While these events are fascinating, they are not an indication of an impending eruption.
“We can detect these changes so clearly and easily,” Poland says. “For the current episode of deformation, we're talking about an inch of uplift that has been associated with a bunch of M1(magnitude 1) and lower earthquakes."
"A few decades ago, we wouldn't have been able to detect so many small earthquakes, and tracking changes in the surface that were so small in terms of deformation would have been challenging. But today, it's all very detectable. We're able to see and understand a lot more thanks to improvements in technology, as well as the expansion of monitoring networks in the area," Poland adds.
Read More: Tracking Past Eruptions In Yellowstone Is Harder Than You Think
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from the Yellowstone Volcano Observatory: Yellowstone earthquakes that are related to ground deformation
- This article references information from the USGS: A history of Yellowstone earthquakes
- This article references information from the USGS: Why are there so many earthquakes at Yellowstone?
