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The name Te Puia (The Geysers/Hot Springs) stands for one of the foremost geyser sites of New Zealand, located in the south of Rotorua. It is part of the Whakarewarewa geothermal area, which also includes the Māori village Whakarewarewa. Latter is managed separately by a different organisation, but both entities share the large Whakarewarewa Sinter Terrace.
The extended blue pool beside the terrace is not fed by its own hot spring but collects water from the geysers. Informally, it is called "The Blueys".
In the narrow sense, the plateau on top of the terrace is called Geyser Flat because it exhibits a remarkably high density of active and dormant geysers. But from a geological point of view, the Geyser Flat extends far beyond this area since the Te Puia Fault, which feeds the geysers with thermal water, runs almost straight from a point north of Kererū Geyser via Pōhutu and Wairoa geysers to Puapua Spring and continues southward. The official tour pamphlet provides a first overview of the most important geysers and hot springs, however, to gain a deeper insight there is no getting around Edward F. Lloyd's Geology of the Whakarewarewa hot springs, NZ Department of Scientific and Industrial Research (DSIR), Information Series No. 11, 1975. Unfortunately, this precious little book can only be obtained from second-hand sources today.
Currently, four regularly active geysers can be observed at Te Puia (Pōhutu, Prince of Wales Feathers, Kererū, and Pareia), and a further five (Waikorohihi, Māhanga, Te Horu, Waikite, and Papakura) may have the potential to resume regular spouting activity as a late result of closing around 300 boreholes in the surroundings since 1987.
However, the full significance of this geyser site becomes clear only in an historical retrospective: about 65 geysers and 500 further hot springs are known, including the 15 m (50 feet) and perhaps up to 20 m (65 feet) high playing Waikite Geyser and Wairoa Geyser, whose eruptions allegedly measured up to 60 m (197 feet), making it the third tallest geyser of New Zealand.
The Te Puia walkways lead visitors on a major loop through the thermal area, while some dead-end trails and subloops give access to additional features. If you hike clockwise as most people do, you come right at the beginning across the main attraction, the Whakarewarewa Sinter Terrace with their geysers.
On a bridge the trail at first passes Kererū Geyser, located at the foot of the terrace. The up to 15 m (50 feet) high playing geyser is named after an endemic New Zealand pigeon because the eruption frequency may vary between repeatedly a day and less than once a week, and is thus as unpredictable and erratic as the bird's behaviour. Even if major eruptions are far less frequent than with Pōhutu, Kererū almost continually emits minor splashes or surges of thermal water and thus built a shiny terrace of its own in front of the vent. In contrast to other geysers on the main terrace, Kererū deposites dark grey, almost black sinter, tinted by pyrite (Fe2S) impurities. With increasing distance to the vent the shade of the sinter fades a little bit. The distinctive chemical composition of the water indicates that Kererū is not directly connected to the other geysers, at least as far as the exchange of fluids is concerned.
We were lucky to catch an eruption of Kererū Geyser, however, not at Te Puia but earlier that day from the observation platform at Whakarewarewa village. While the first bursts came out of a sudden, the geyser continued with longer interruptions and decreasing height over a period of more than 30 minutes. Small splashes as shown on the pricture above still took place for hours afterwards. On the next picture also a more than fist-sized piece of sinter is recognizable, which was ejected by the eruption.
The shape of Kererū's black vent and cone directs the main volume of the eruption column straight up into the air, and a smaller part obliquely fans out to the north. On the next picture it can also be seen by the cream-coloured sinter channel that thermal waters from the top of the sinter platform discharge into Kererū's cone. That may have some influence on its intervals.
The pleasure of experiencing Kererū's eruptions would currently not exist without the above mentioned shutdown of bores, because previously, from 1972 to 1988, no larger activity could be observed. In the period from 1988 to 2000 eruptions were still small and very rare, from 2000 to 2014 the geyser resumed regular eruptions up to 5 m (16 feet) height followed by a full recovery of its play after 2014.
Within the runoff channel of Kererū a tiny perpetual spouter is to be found. At this position or at least not far from it formerly a mud geyser called The Torpedo was active. Makereti "Maggie" Papakura, one of the most famous Whakarewarewa tourist guides at the beginning of the 20th century, described the activity of Torpedo as "an explosion caused by the boiling mud and the cold water meeting. The mud sometimes is thrown up a foot, and sometimes fifteen feet." (M. Papakura, Guide to the Hot Lakes district and some Māori legends, Brett, 1905).
Immediately at the base of the terrace another little spring has built up a small-scale sub-terrace, featuring pink-hued sinter stalactites and colonised by colourful thermophile organisms.
South of Kererū and on top of the Whakarewarewa Sinter Terrace, Prince of Wales Feathers Geyser and Pōhutu (which translates as "geyser") are offering an amazing spectacle. They are not only adjacent but also closely related to each other, so one cannot be described without the other. The reason for the dependency is that all geysers on top of the terrace are interconnected via the Te Puia Fault. Usually, Prince of Wales Feathers Geyser precedes Pōhutu a little bit and acts as an indicator, but at the latest when the angled jets of Prince of Wales Feathers have reached their full eruption heights of up to 9 m (30 feet) Pōhutu sets in. Then it dwarfs Prince of Wales Feathers Geyser by its mighty water column of 15-20 m (50-65 feet) height. Even bursts reaching 30 m (98 feet) do occur.
Both intervals and eruption durations of Prince of Wales Feathers Geyser and Pōhutu Geyser are quite variable, whereby a typical interval is said to be somewhat more than one hour. On our visit the quiet times between the eruptions were exceptionally short, in the range of a few minutes or less. All the remaining steaming and splashing made it hard to capture photos on which the geyser orifices were clearly visible. My best attempt shows the mouth of Prince of Wales Feathers Geyser with smooth surfaces in vivid colours.
This geyser's original and still valid name is Te Tohu (The Indicator), but it got a second name in 1901 on the occasion of a visit of the Prince of Wales, the later King George V. The idea was born because the geyser’s plume resembled the feathers on his coat of arms. Te Tohu is known to be much younger than Pōhutu. Its formation was induced by the violent eruption of the Tarawera volcano in 1886.
If you look at Pōhutu from the south not only the reddish ornamentation of the geyser cone but also the sulfur coated sinter stalactites in its surrounding create the impression of a magical world.
Pōhutu Geyser offers the visitor on the nearby walkway no insight into its orifice. All you can see from there is the outer slope of the cone. However, southeast of the Geyser Flat there is an elevated observation platform which provides a better viewing angle once the abundant steam has cleared the viewline. The inside of Pōhutu's crater displays some unexpected structural details and colours.
Immediately south of Pōhutu the large, rectangular pool of Te Horu Geyser (The Roar) shows up. Steam on Geyser Flat makes it not always easy to get an undisturbed look at it. Te Horu went dormant in 1972 and has not recovered by the shutdown of bores until now. Before 1972, it erupted up to 7 m (20 feet) high at an interval around 2 hours. It has not yet been proven if air-cooled water from Pōhutu's eruptions, which falls into Te Horu at northerly winds, leads to a delay in Pōhutu's intervals. This is logical to assume because of the close subterranean connection between the two systems.
Farther south of Pōhutu and Te Horu a large, very prominent sinter cone rests on Geyser Flat not far away from the trail. Its structure gives a clear indication that it had been a major geyser in the past. Unfortunately, I was not able to get sufficient information about this feature until now. In his 1921 book The Hot Springs of New Zealand, Arthur S. Herbert shows a picture of this cone and refers to it as dormant geyser but gives no name.
Adjacent to the unnamed cone two further geysers were supplied with hot water by the fissure through Geyser Flat, however, both are dormant now. The one closer to the trail and easier to spot is Māhanga Geyser (The Twins). Because of its shape it is also called The Boxing Glove. Unlike many other geysers, it only started to erupt in 1961 and went dormant again in 2001. Māhanga's sinter structures indicate, though, that it must have been a geyser since ancient times. Eruptions were described to be up to 4.5 m (15 feet) high. Currently Māhanga acts as a steam vent.
In close vicinity of Māhanga Geyser, only 4 m (13 feet) to the northeast, the second one, Waikorohihi Geyser (Loudly Hissing Water), is to be found. Unfortunately, it sits beyond Māhanga Geyser as seen from the nearest trail, and moreover, its cone opens to the northeast. This virtually obscures Waikorohihi Geyser from trails and platforms at Te Puia if it is not erupting. I tried to capture a photo from the observation platform southeast of Geyser Flat, but the result was unsatisfactory. Only steam from the merely visible depression indicates the position of Waikorohihi's vent.
Even though further away, the upper observation platform at Whakarewarewa village supplies a better viewing angle. It likewise does not permit a look at the vent, though. At least the flat funnel structure above the vent becomes visible. Waikorohihi Geyser features no surface pool.
Waikorohihi used to emit a stout water jet from the very narrow vent. As was written on an information board next to the geyser, the fountains reached a height of 3-5 m (10-16 feet) at an interval around one hour and a half. But the frequency declined strongly since 2000 until the eruptions ceased in 2004. In 2015 some new activity was observed, but it turned out to be a short intermezzo. Just as in case of Māhanga currently only steam is emitted.
On the picture above at some distance in front (east) of Waikorohihi the location of Te Waro Geyser (The Abyss) can be spotted, which already was extinct in the 19th century. Meanwhile Waikorohihi's runoff has sealed the vent completely. Te Waro became popular because in the 1880s and several times afterwards people descended into the upper chamber of its subterranean plumbing system, called Heketanga Cave. John S. Rinehart described such an experiment, carried out by a Mr. Martin, as follows: "Only in one case, the extinct Te Waro Geyser of Whakarewarewa, has man been able to climb down inside the reservoir itself. Although the opening to Te Waro's original reservoir is now covered with sinter deposits, in 1921 the external vent was "a circular hole with ... typical round sinter edges of a geyser, just large enough for a man to squeeze his body through". Mr. Martin's investigation has been described: The bottom of the shaft is 15 ft [4.6 m] below the surface, and it opens out into a chamber 12 ft [3.6 m] long and 9 ft [2.7 m] high ... In the floor of the chamber are two fissures, one of which ... is supposed to connect with Pohutu Geyser and whence come the rumblings of fiercely boiling water." (J.S. Rinehart, Fundamentals of Geyser Operation. In: Geysers and Geothermal Energy; Springer, New York, 1980).
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