The largest acidic geyser has been putting on quite a show

Source: Hacker News

Overview

Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week’s contribution is from Michael Poland, geophysicist with the U.S. Geological Survey and Scientist‑in‑Charge of the Yellowstone Volcano Observatory.

Norris Geyser Basin is known for being the hottest and most dynamic of Yellowstone National Park’s thermal areas—and that’s saying something! It is home to Steamboat Geyser, the tallest active geyser on Earth, and it contains an interesting and chaotic mix of acidic and neutral features in terms of chemistry.

In the Back Basin of Norris Geyser Basin, about 200 m (660 ft) away from Steamboat Geyser, is Echinus Geyser. The name comes from mineralogist Albert Charles Peale, who visited the geyser in 1878 and thought the rocks around the geyser looked like sea urchins—a type of animal known as an echinoderm.

Physical Characteristics

• The geyser pool is about 20 m (66 ft) across.
• It has an acidic chemistry and is the largest acidic geyser in the world. The acidity is mild—comparable to orange juice or vinegar.
• Acidic water can break down the rock that makes up a geyser’s plumbing system, but at Echinus the acidity results from mixing acidic gases with neutral waters, so it does not erode the conduit.
• The pool rim is red from iron, aluminum, and arsenic, and silica‑covered spiny rocks give the geyser its name.
• A boardwalk with several benches and multiple tiers of platforms surrounds the geyser.

Historical Activity

Early History

• Mostly dormant with only occasional eruptions prior to 1948.

1970s

• Erupting regularly at 40–80‑minute intervals.

1980s–1990s

• Eruption durations could be extreme, sometimes lasting more than 90 minutes.

When the geyser was vigorously active, eruptions varied tremendously. Some were small, while others reached about 23 m (75 ft). They could be vertical or inclined, occasionally soaking onlookers with warm water, and were regular enough that the park sometimes posted predictions—the duration of an eruption often forecasted the timing of the next one.

By the early 2000s, eruptions began to wane and activity became much less common.

Monitoring and Recent Activity

2010–2011

• A temperature monitoring system was installed in the outflow channel (details).
• Recorded 15 sporadic eruptions during October 2010 – January 2011.

2017 Surge

• Mid‑September 2017: temperature spikes followed by decreases, indicating surface agitation and hot‑water release down the channel (not true eruptions).
• October 2017: true eruptions began, with higher temperature spikes.
• October 18 – November 10, 2017: eruptions occurred consistently every 2–3 hours, then stopped abruptly.
• Isolated eruptions followed in January 2018, January 2019, and two in December 2020.

2026 Reactivation

• Early February 2026: repeated surges resumed.
• First eruption since 2020 on February 7. Additional eruptions on February 9, 12, and 15.
• Starting February 16, eruptions occurred every 2–5 hours.
• Current eruptions last 2–3 minutes, reaching 6–10 m (20–30 ft). After an eruption, water level drops significantly and takes about an hour to return to normal.
• This pattern mirrors the late‑2017 activity.

You can follow the activity via the temperature graphs on the Yellowstone Volcano Observatory website. Spikes reaching 70 °C (158 °F) indicate eruptions; spikes of 40–50 °C (104–122 °F) represent surges.

Outlook

Will the eruptions continue into the summertime, allowing visitors to use the seating and viewing areas as intended? It is unlikely, given the geyser’s tendency to awaken for a month or two before returning to dormancy, and there were no eruptions during the last few days of February. However, conditions at Norris Geyser Basin can change, so the show may continue into the summer.

Acknowledgement

Some of the information for this article was derived from T. Scott Bryan’s The Geysers of Yellowstone, Lee H. Whittlesey’s Yellowstone Place Names, the online GeyserTimes database for Echinus Geyser, U.S. Geological Survey Professional Paper 1456, and research by M. A. Bellingham.