Frying Pan Lake (renamed Waimangu Cauldron in 1963 though not widely used) is the world's largest

hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal activity, geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...

. It is located in the Echo Crater of the

Waimangu Volcanic Rift Valley The Waimangu Volcanic Rift Valley is the hydrothermal system created on 10 June 1886 by the volcanic eruption of Mount Tarawera, on the North Island of New Zealand. It encompasses Lake Rotomahana, the site of the Pink and White Terraces, as wel ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

and its acidic water maintains a temperature of about . The Lake covers in part of the volcanic crater and the shallow lake is only deep, but at vents, it can go down to . Echo Crater was formed as part of the 1886

Mount Tarawera Mount Tarawera is a volcano on the North Island of New Zealand within the older but volcanically productive Ōkataina Caldera. Located 24 kilometres southeast of Rotorua, it consists of a series of rhyolitic lava domes that were fissured ...

eruption, which opened several

crater A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...

s along a rift stretching southwest from Mount Tarawera to the nearby Southern Crater. After this event, the crater's floor partly filled with rainwater and heated

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

, but it was not until after a large eruption in Echo Crater on 1 April 1917 that the resulting larger crater filled up from hot springs to reach its current size by mid 1918. The most recent eruption in Echo Crater occurred on 22 February 1973, destroying the Trinity Terrace area on the south-eastern shore of Frying Pan Lake. An area of colourful sinter terraces is still visible on the western shore of the lake. To the north, the lake is bounded by the steaming Cathedral Rocks. This monolithic rock structure is composed of

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The miner ...

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

at least 60,000 years old and was named Gibraltar Rock until the 1917 Echo Crater eruption completely changed its shape. A

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or another rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

known as the Devil's Blowhole in the northern wall of Echo Crater also disappeared in that event. The water of Frying Pan Lake is typically steaming and can appear to be boiling, due to carbon dioxide and hydrogen sulphide gas bubbling to the surface, but the lake's average temperature is .Waimangu Wanderer Guide, April 2014 The lake and its outflow, Waimangu Stream (referred to as Hot Water Creek in the Waimangu Wanderer Guide), have an average pH level of 3.8, even though some of the boiling hot springs and vents on the lake's bed feed it with alkaline water of pH 8.2 to 8.7. This leads to various gradients of pH levels, which govern which types of algae are present, the blue-green algae ''Mastigocladus laminosus'', or the eukaryotic algae ''Cyanidium caldarium''. The unique cyclic nature of the

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

system interconnecting Frying Pan Lake and the nearby

Inferno Crater Lake Inferno Crater Lake is a large hot spring located in the Waimangu Volcanic Rift Valley on the North Island of New Zealand, and the largest geyser-like feature in the world. The actual geyser is not visible, as it plays underwater at the bottom ...

has been the subject of studies since monitoring equipment was installed in 1970 at the outflow stream from Frying Pan Lake and at Inferno Crater Lake.Information panel "Waimangu Monitoring Station" at the outflow from Frying Pan Lake,

GNS Science GNS Science (), officially registered as the Institute of Geological and Nuclear Sciences Limited, is a New Zealand Crown Research Institute. It focuses on geology, geophysics (including seismology and volcanology), and nuclear science (partic ...

and

Waikato Regional Council The Waikato () is a Regions of New Zealand, region of the upper North Island of New Zealand. It covers the Waikato District, Waipā District, Matamata-Piako District, South Waikato District and Hamilton, New Zealand, Hamilton City, as well as ...

Both lakes' water levels and overflow volumes follow a complicated rhythm that repeats itself roughly every 38 days. When the water level and temperature of Inferno Crater Lake increase, the water level and outflow of Frying Pan Lake decrease. The outflow volume of Frying Pan Lake has decreased from over in 1970 to around in 2014, but varies by up to as part of the 38-day cycle. Frying Pan Lake is one of the first major attractions encountered along the main Waimangu walking track. The site of the extinct

Waimangu Geyser The Waimangu Geyser, located near Rotorua in New Zealand, was for a time the most powerful geyser in the world. The geyser was seen erupting in late 1900. Its eruptions were observed reaching up to in height, and it excited worldwide intere ...

is located not far from its north-eastern shore.

References

{{Authority control Rotorua Lakes District Landforms of the Bay of Plenty Region Okataina Volcanic Centre Hot springs of New Zealand

See also

References