Historically, Echinus Geyser has been a real crowd pleaser, the only "predictable" geyser in Norris Geyser Basin. Unfortunately, it didn't always live up to its reputation in 1998, when it had many aborted and wimpy eruptions. As of February 1999, Echinus was being described as fairly weak and erratic. Intervals were close to 90 minutes, durations were around 4 minutes, and maximum heights were only about 35 feet. Eruptions were preceded by about 20 minutes of overflow. Not long after this, Echinus entered into a period of reduced activity that continues to this day (July 2017). A few eruptions have been reported during most years, most recently one in November 2015 that was logged electronically but not seen, but nothing remotely approaching its frequency of the past.
When Echinus is playing well, it is not uncommon to hear first-time observers comment that they've enjoyed Echinus more than Old Faithful. It is possible to get closer to Echinus than to any of the other predicted geysers. This coupled with the wildly bursting play of Echinus makes it a treat to watch.
Echinus is a fountain-type geyser. Its maximum height is about 80-125 feet but most bursts are less than this. Its duration ranges from a minute to over an hour, although most eruptions last between 5 and 15 minutes. Its intervals, when active, range from 20 to 80 minutes. When active, given Echinus Geyser's great show and its relatively short interval, it is worth waiting for even if you don't know the next prediction. Now, however, you must be very lucky to see it.
Echinus is the largest frequently active acid geyser in the world. Unlike most geysers in Yellowstone and around the world which tend to be alkaline in nature, Echinus, along with most of the other thermal features at Norris Geyser Basin, erupts water with a pH as low as 3.3.
|Historically, Echinus erupted from a pool that was not necessarily "full" but was "filling" -- in some years the eruption waited for a full pool or overflow, while in others, it would erupt before the filling was complete. Whatever the pool level, the key observation was of bubbling over the vent that would intensify into a boil, then a surge, and then very quickly, the eruption. Unfortunately, as Echinus fell into near-dormancy, bubbling over the vent, sometimes lasting literally for hours, was observed that did not lead to an eruption. Accordingly there is no money-back guarantee on this analysis. Early reports of the October 2017 rejuvenation, however, do suggest a return to the historic pattern.