Grand Geyser

If there is one (predictable) geyser other than Old Faithful that is worth is seeing in Yellowstone National Park, it would be Grand Geyser. Located about a quarter mile from Old Faithful via several routes, Grand is located in a alcove against a large rocky hillside. It is surrounded by a massive viewing area, where there are almost two dozen benches placed so you can wait for the geyser. This set up is for good reason, as Grand is the largest predictable geyser in the world, and every eruption is a sight to behold.

Grand Geyser's pool on an early morning. Photo by Micah K.

The reason that Grand Geyser is so special is because Grand is the largest predictable geyser in the world, there are several geysers that are larger and last longer, but are not predictable, Grand is predicted by the National Park Service, and visitors can find prediction times in the visitor center by Old Faithful or by calling in the prediction hotline when it is available during the summer season. (I will post it when it becomes available)

The geyser prediction board at the Old Faithful Visitor Center front desk. Photo by Janet W.

 Grand Geyser erupts about every 6-9 hours (the prediction for the summer was 7.5 +/-2 hours), and the eruption lasts 10-15 minutes. Being the largest predictable geyser in the world, Grand reaches heights of up to 180 (rarely 190) feet, being 30-50 feet taller than the average Old Faithful eruption which is 135-150 feet.
 

Grand Geyser at it's zenith from near Castle Geyser. Photo by Micah K.

Despite it's relative regularity, Grand is not a solo player. It is closely related to several other Geysers surrounding it which have been grouped together in the "Grand Group". Two of these geysers are especially closely tied to Grand; Turban and Vent. Turban Geyser is located just North (left from the benches) of Grand, and is a fountain geyser that erupts from a large sinter bowl . Many visitors mistake this bowl for Grand, when in fact Grand is the shallow inconspicuous pool right next to Turban.Vent is a small, well, vent, nearly hidden in a small alcove against Turban Geyser's shoulders.Turban's frequent bursting eruptions usually reach heights of only 5-10 feet, but when accompanying Grand (see below) it's water droplets can climb to 20 feet.

Turban Geyser in eruption (the large sinter rim) with Grand's pool in the foreground. Photo by Micah K. 

Vent Geyser at full height. Photo by Micah K.

Turban and Grand are intimately linked. Turban erupts about every 15-20 minutes. Simultaneously, Grand's pool cycles up and down. Geyser Gazers watch these cycles closely, and with experience it is possible to judge if Grand has potential to erupt on each cycle. When Grand is ready to erupt, it's pool rises to overflow and the level plateaus. Then, palpitations in the pool will cause a chain of waves to ripple across the pool. Eventually these waves becomes almost impossible to miss. At this point the Geyser Gazer who's calling Grand makes a "Wave's on Grand, Waves on Grand" call to let anyone nearby to hustle up.

Waves on Grand, early morning. Photo by Micah K.

When waves become visible Grand can do one of two things, it can drop and the cycle can start over again, in which sometimes it takes another hours and a half to get another good try. Or Grand will erupt. There are two ways that Grand starts an eruption. There is the "Grand Start" and the "Turban Start". With the Grand Start, Grand beats Turban to the punch. The waves on the pool will build, and the palpitations will become a vigorous boil, suddenly a column of superheated water will explode from the pool, climbing into the sky and sending a 3 inch high wave of superheated water cascading down Grand's beautiful geyserite terraces. Turban Geyser erupts within 30 seconds, much larger than it's solo eruptions.

With a Turban start, Turban Geyser beats Grand to eruption first. Usually Turban will be noticeably bigger and more vigorous if Grand is going to erupt on that cycle. Once Turban starts, If Grand is going to erupt, it does so within 90 seconds of Turban.

A "Turban Start" of Grand Geyser on a gorgeous summer day with excited Geyser Gazers. Video by Micah K.

Vent Geyser does not participate in the energy battle that takes place between Grand and Turban, rather, it waits until about 2-3 minutes after Grand erupts, and then suddenly bursts out of hiding with a feather-like 75 foot jet of water.  All 3 geysers continue to play for several minutes, then you get to the time where you can get a second "burst" out of Grand.

2nd Burst of Grand Geyser

Most Grand eruptions only have one burst, which begin with the initial massive water column climbing to 150-180 feet. Then about a minute or so into the eruption, the style switches and the eruption is characterized by a series of individual jets of water and steam that can reach 90-120 feet, accompanied by Vent's angled column and Turban's massive bursting.6 minutes into Grand's first burst, you enter into a window of opportunity. If a second burst is to happen, Grand will suddenly cease 6-9 minutes after starting and the water will drain out of sight. To unexperienced observers, it appears that the show is over, it becomes eerily quiet without the massive WHUMPH of Grand's jets, although Turban and Vent will continue to play. But suddenly blue boiling water will reappear in the shallow crater, boiling violently, the entire pool undulating. At this point Gazers are usually up on their feet, urging Grand on, but it can still drop and end the eruption, which happens frustratingly often. But there is the occasional time when that isn't the case, and instead, after surging an agonizing few seconds. Another massive column of water explodes from Grand's Pool, reaching 170-180 feet in seconds. The 2nd burst usually lasts only about 30 seconds, but it is still all the more spectacular, and it's a treat that all Geyser Gazers enjoy. Two burst eruptions are rare nowadays in themselves, but Grand has been known to have up to 11 bursts.

A video of an extremely rare 10 burst Grand with ecstatic Geyser Gazers. Video by. David Schwarz.

Vent, Turban and Grand erupt together joined by a rainbow. Photo by Micah K.