Yellowstone Caldera getting more active

quote:

---

While driving south from Mammoth Hot Springs towards Norris Geyser Basin early on August 5 last summer, a park scientist noticed a billowing steam column through the trees and across a marshy expanse. The eagle-eyed scientist notified the park geology team to verify if this was indeed new activity.

This new hydrothermal feature is within a region called the Roadside Springs thermal area, which is a collection of spatially distinct areas of altered rock and hydrothermal features (data for Yellowstone thermal areas is at https://data.usgs.gov/datacatalog/data/USGS:661d5eb7d34e7eb9eb7e3a41). This new feature is at the foot of a rhyolite lava flow about 3 meters above the marsh below, and it lies within a swath of warm, hydrothermally altered ground that is approximately 60 meters (about 200 feet) long.

Soon after it was identified, park geologists trudged through the marshy ground to get a closer look that the feature, which had a temperature of 77 °C (171 °F). A very thin veneer of grey silicious clay barely covered the surrounding surface, indicating its very young nature.

Although this hydrothermal activity may seem new to us, it may also just be just the latest manifestation of activity a short distance away that kicked into existence more than two decades ago. On March 10, 2003, a similar type of hydrothermal activity was first observed on the other side of the same rhyolite lava flow where the new feature is located, just west of Nymph Lake. This hydrothermal activity persists through this day but is much less energetic than when it first formed.

Are the new feature and the activity that started in 2003 hydrologically connected? Probably. One could run a line along the axis of the older active area and it would intersect the new feature. This line also follows the trend of faults that run from Norris Geyser Basin northward to Mammoth Hot Springs and beyond.
.

The new feature remained prominent into the fall of 2024, with a strong steam plume that was especially visible during chilly mornings. But as fall began to turn into winter, the steam plume gradually disappeared. The feature remains active, but there is some water in the vent, decreasing the amount of steam that is released. Whether or not the strong plume returns in the summer of 2025 remains to be seen.

Geologists have mapped more than 100 major hydrothermal areas in Yellowstone National Park, and there are many more than 10,000 hydrothermal features within its boundaries. The activity from these features waxes and wanes with time—you might even say that some of them pick up steam! Sorry…we couldn’t resist.

---