Strokkur

Coordinates:	64.3132 N 20.3024 W
No:	234        (list of all attractions)
Category:	Geysers, Springs
Values:	Geology, Visual
Rank:	3
Height:	Historically - up to 60 m, now - up to 40 m
Address:	Europe, Iceland, Suðurland, 100 km drive north-east from Reykjavík, Haukadalur geothermal field

Strokkur in the evening light.
Auslandsoesterreicherflickr- accountinhaber, Flickr / CC BY 2.0

Strokkur shortly before eruption.
Andreas Tille, Wikimedia Commons.CC BY-SA 3.0.

The famous bubble of Strokkur is rising.
Andreas Tille, Wikimedia Commons.CC BY-SA 3.0.

Bubble is broken and Strokkur erupts.
Andreas Tille, Wikimedia Commons.CC BY-SA 3.0.

Strokkur is dormant, circa 1900.
Icelandic and Faroese Photographs of Fredrick W. W. Howell, Cornell University Library. Public domain.

Currently Strokkur ("the churn") belongs to the most spectacular geysers on Earth. But not always it has been like this - circa 1900 it seemed to be extinct.

Photogenic eruptions

Strokkur is the main attraction in the beautiful Haukadalur geothermal area.

In fact this is the only reliable geyser in this famous geyser field. Every few minutes it forms some 10 - 20 m tall fountain, first starting with an unique bubble. Sometimes fountain is even 40 m high.

After the eruption the pool of geyser is emptied - but it quickly (even in 10 seconds) fills up. Before the eruption the pool is pulsating up and down and then a pulse of steam pushes the water upwards, forming a weird bubble with steam visible through it!

The steam breaks the bubble and eruption starts. For most part there is one powerful burst, but there may happen several bursts as well.

Changing activity

Although now Strokkur is very active, not always it has been like this.

This geyser was first noticed in 1789, when after an earthquake it was erupting up to 40 m high.

According to reports of several scientists the power of eruptions fluctuated in 19th century. In 1810 George Mackenzie reported that Strokkur is some 20 m high and eruptions were lasting for half an hour. In 1815 Henderson estimated that it is even 60 m high. Professor Bunsen in 1846 estimated it to be 50 m high. At the end of 19th century geyser increased its activity.

Earthquakes at the turn of 20th century made Strokkur silent - just a steaming hole wit water deeper in it remained.

It remained like this until 1963 - then the vent was thoroughly cleaned with a drill up to 40 m depth through the bottom of its basin (as advised by Geysir Committee). This action was very successful - since this time Strokkur is the main attraction in Haukadalur, with its spectacular and frequent eruptions visible for afar.