Yellowstone’s Giant Geyser erupted three times in October, and Echinus Geyser blew too

Giant Geyser can throw water 250 feet into the air and keep going for more than an hour, so three eruptions in one month is a notable run. The Yellowstone Volcano Observatory logged them on Oct. 5, Oct. 13 and Oct. 22, and added that Echinus Geyser in Norris Geyser Basin erupted on Oct. 26.

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Both geysers spent long stretches asleep before 2026, which is why a tidy list of dates carries more weight here than it would for Old Faithful. The two sit in different basins, Upper Geyser Basin and Norris, and their October entries came from the same monthly update.

Giant, after decades of erratic behavior

The National Park Service’s Giant Geyser page describes a feature in the Upper Geyser Basin, near Old Faithful, that went dormant in 1955. It then woke slowly and unevenly, erupting more than 50 times in 2007 and just once in 2010. Eruptions can reach 250 feet and last more than an hour.

The October dates come from the observatory’s Nov. 2 monthly update, which lists the three eruptions and puts the first two just eight days apart and the second and third nine days apart. A month that held that many Giant eruptions would have been remarkable in the lean years the park page describes, when the geyser managed a single eruption in all of 2010.

Listening for Giant with infrasound

Giant resumed erupting in summer 2026 after its latest quiet spell, according to a column by Michael Poland and Jamie Farrell describing a new sensor station on Geyser Hill. Poland is the geophysicist who serves as the observatory’s Scientist-in-Charge; Farrell is its chief seismologist at the University of Utah. The station, called YGH, carries weather, seismic and infrasound instruments, and its microphones picked up eruptions from Old Faithful, Grand Geyser and Giant.

The column gives a worked example. At 9:14 p.m. MDT on Sept. 10, 2026, infrasound arrays at YGH and at Biscuit Basin both recorded a strong signal, and the compass bearings from the two sites converged on Giant, which had begun erupting. Poland and Farrell present it as proof that several stations together can triangulate the source of an unusual sound, a capability the observatory wants for spotting hazardous steam explosions.

Echinus: a weak-acid geyser with a long on-and-off record

Echinus sits in the Back Basin of Norris, about 200 meters from Steamboat Geyser, and is billed as the largest acidic geyser in the world. Poland wrote in a USGS item on its return that the acid is mild, comparable to orange juice or vinegar, and too weak to erode the surrounding rock. The geyser was named in 1878 by mineralogist Albert Charles Peale, who thought its silica-crusted rocks resembled sea urchins.

The pattern since then has been feast and famine. It erupted every 40 to 80 minutes in the 1970s, ran long eruptions in the 1980s and 1990s, faded in the early 2000s and put on a regular show in 2017 before stopping that November. Eruptions resumed on Feb. 7, 2026, and from Feb. 16 came every 2 to 5 hours. Recent bursts reach about 20 to 30 feet and last 2 to 3 minutes. Poland suggested the run might not last into summer, adding that “change is constant at Norris Geyser Basin.” A temperature sensor in the outflow channel tracks it, with spikes near 70 degrees Celsius marking eruptions.

A single recorded eruption on Oct. 26 shows Echinus still working in the fall, though the update gives a count of one for the month. That is a long way from the every-2-to-5-hours rhythm of late winter, and the update does not say whether eruptions went unrecorded between the observatory’s looks, so the single date is best read as a floor, not a full census.

Elsewhere on the October ledger

The same update says Steamboat Geyser had only minor eruptions and has had one major eruption so far in 2026, a tally the park’s Steamboat eruption table dates to Feb. 27. A small collapse pool in Biscuit Basin, created by the June 13, 2026 hydrothermal explosion, erupted at least twice.

Steamboat sits a short walk from Echinus in the Back Basin and is the world’s tallest active geyser, with major eruptions that clear 300 feet. The park’s table lists three major eruptions in 2025, six in 2024 and, so far, one in 2026. Its minor eruptions, which reach 6 to 40 feet and last 1 to 4 minutes, are the ones the October update counts, and the park describes both kinds as entirely unpredictable. The observatory’s ten-year monitoring plan, begun in 2022, calls for sensors in geyser basins to catch hazardous hydrothermal changes such as steam explosions, and the Norris network dates to 2023.

The update gives no interval for Giant, and the park page lists none either, so whether three October eruptions signal a steady cycle or another burst before a pause is unanswered.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.