Geysir Strokkur

Geysir Strokkur Iceland is one of the most obstinate geysers in the planet and it’s situated in a geothermal area beside River Hvita, lying in the Huakadalur Valley at the base of Laugarfjall, east of Reykjavik in South West Iceland. Strokkur was first reported in the year 1789, after an earthquake which probably unblocked or created its canal. Eruptions were common until the year 1896, after which a renewed earthquake incapacitated the geyser. In 1963, the natives succeeded in unclogging the plumbing system and Geysir Strokkur has been active ever since. The first ever recorded geyser activity in this region dates back to 1294, when the great Geysir is said to have become active.

Different Stages of Eruptions

Strokkur is an extremely active geyser, it erupts approximately every four to eight minutes, generating plumes 15 to 20 m high, and reaching velocities of 64km/h. Before eruptions, the pool is full and pulsates gently up and down. The eruptions starts when a pulse of vapor rising from below pushes the water in the pond upwards forming a huge bubble (or dome) of water through which the vapor spurts and expels plenty of the water in the pond skywards. After several eruptions the pond is empty but is quickly refilled by flow-back and water rising from below. Following smaller uneven eruptions which are also regularly observed, the pond may remain almost full and renewed activity may occur very fast.
Geysir Strokkur Iceland is a popular tourist attraction. In 1894, the region was sold to James Craig who fenced-in the geyser spot and requested entrance fee. However, this was short-lived and people were allowed to visit the site freely again the following year. Presently, the area belongs to the Icelandic state and is regularly visited as part of the Golden-Circle tour which takes travellers to a number of sites in Southern-Iceland.

How Does A Geysir Work?

A geyser often requires a source of water, a source of heat (cooling magma), permeable rocks through which super-heated waters can rise and a pressure tight chamber where pressure can build up before eruption. Geysers are usually found in highly silicic rhyolitic rocks. Super-heated waters liquefy silica from these rocks at temperatures of about 300 degrees Celsius which exist in the high pressure setting deep under the surface. Silica dissolves again and is deposited when the super-heated waters boil/cool as pressure and temperature fall. The deposited geyserite covers the geysers plumbing system, allowing it to pressurize.

Geysir Strokkur Iceland is situated in an area with plenty of geyserite deposits, but is bounded by minor travertine sinter formations, which can perform a similar sealing function. Travertine formation is supported by carbon-dioxide gases rising from beneath which dissolves calcium out of the underlying rocks forming calcium-carbonate. This is transferred to the surface dissolved in the geothermal waters and is left there once the waters vaporize.

In a dynamic geyser system, super-heated waters rise into the geysers chambers, whilst cooler near surface waters may also enter the chamber from above. This covers the water body below keeping it pressurized and allowing it to maintain temperatures above boiling point under atmospheric-pressure-conditions. As the hollow fills, the super-heated water body transfers heat to the cooler water above. Finally, the upper water body reaches boiling-point. As heating continues gas (water vapor) formation becomes more vibrant and water starts to be pushed out of the vent. Eventually, the increasing concentration of bubbles (domes) reduces the quantity of the upper water body, thus decreasing the pressure acting on the body of super-heated water underneath. This depressurization causes vigorous “run-away” vaporization of the water underneath, resulting in water and vapor being vigorously expelled upwards, causing the eruption. Eruptions at Geysir Strokkur Iceland are very short, each involving one or multiple discrete thrusts. In the geaothermal system feeding Geysir Strokkur Iceland, sub-surface temperatures of around 240 degrees Celsius are believed to exist, possibly at a depth of one kilometer and below.


Due to the reliability and frequency of its eruptions, Geysir Strokkur Iceland is a popular tourist attraction. It’s surrounded by algal deposits, fumaroles, mud pools, and other geysers. Strokkur forms part of the Golden Circle, the most famous and most travelled tourist route in Iceland. Geysir Strokkur Iceland is the only one hour drive geyser from Iceland’s capital Reykjavik. For those without a private means of transport, several companies offer coach trips to this site. Hotels and restaurants facilities are available just over the road from Geyser Strokkur, and a small camping site is just nearby.

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