Geysir and Strokkur: Iceland’s Geothermal Area

Geysers are pretty incredibly geological sites. In layman’s terms, they are hot springs that periodically burst up with gas, making a water explosion appear on the surface.

There are many geysers around the world, typically where there are tectonic plates, geothermal hot springs, and volcanos. One of the most famous geysers in the world is the Geysir, sometimes known as The Great Geysir, located in the Haukadalur Valley, a favorite stop around Golden Circle.

What is a Geyser?

A geyser is a hot water spring that periodically shoots steam/gas above the surface due to the pressure built inside the earth.

Geysers are pretty rare, with an estimated 1,000 of them worldwide. The most noticeable and largest of them all is Old Faithful in Yellowstone National Park. The next best-known geyser exists in Iceland, known as ‘Geysir’ or ‘The Great Geysir.’

Around the Geysir hot spring area are other geysers that bubble, burst, and spurt: the most noticeable being the Strokkur geyser.

Geysir very much produces spurts of water, just like submarine volcanos do, due to the pressures built up inside the ground.

How Geysers Erupt

For a geyser to erupt, certain specific geological conditions have to be met. These include:

1. Groundwater Source. This refills the geyser’s underground reservoir every time there is an eruption.
2. Hot rocks below the ground surface (heat source). The heat source superheats the water underground, enabling the water to boil and ‘erupt’ to the surface.
3. A water reservoir below the ground. It is through the underground reservoir that the superheated water/steam can increase the water reservoir’s temperature until the pressure is too much and explodes as an eruption above ground – this is when the pressure of the water pushes down on the superheated steam at the bottom of the geyser is not enough to stop the superheated steam from escaping.
4. Cracks/holes allow the water to burst to the surface (aka fumaroles). Without an entry point above the ground, the superheated water/steam would not be able to escape. It is due to the cracks/fumaroles that the water escapes, causing an eruption of hot water and steam above the ground.

Largest Geysers in the World

Below are the top 5 largest geysers in the world:

1. Old Faithful: located in Yellowstone National Park, USA. This geyser erupts roughly every couple of hours to heights of up to 180 ft (55 meters).
2. El Tatio: located in Andes Mountains, Chile. Although not the tallest spurting geysers, there are over 80 active geysers in the area, making for quite a sight.
3. The Great Geysir: located in southeast Iceland. This is the largest geyser in Iceland and infrequently erupts (2000 and then 2016). Watch below the rare sighting of the first recorded Geysir activity in 1950.
4. The Lady Knox Geyser: located in the Waiotapu area, New Zealand. It was discovered as a geyser when prisoners washed their clothes in the geyser, with the soap inducing an eruption. Eruptions are still induced through the use of soap to this day.
5. Steamboat Geyser, located in Yellowstone National Park, USA. This geyser can spurt water up to 300 ft (91 meters) into the sky, but is not very active, much like the Great Geysir.

The Great Geysir

Iceland’s largest Geyser

Technically still active, but very infrequent

Although the Great Geysir is the largest geyser in Iceland, it is not the most active, with that going to a sister geyser in the hot springs area, the Strokkur geyser. Derived from the English word for ‘geyser,’ Geysir was coincidentally also the first geyser to ever be described in the literature in the 13th century, making it the first geyser that was known to Europeans. It is estimated that the eruptions of gas/steam travel from a depth of 1-2km before finally reaching the geyser’s surface.

The recorded eruptions timeline for Geysir is as follows:

• 1630 – eruption was so violent that it is recorded to have induced a small earthquake.
• 1845 – the eruption was believed to have reached 557 feet (170 meters) high, making it the highest recorded burst ever by Geysir.
• 1846 – in the mid-19th century, Geysir erupted multiple times and was sourced by Robert Bunsen to reach heights of around 150 feet (45 meters).
• 1896 – an earthquake on 10th September 1896 induced Geysir to start erupting again, multiple times a day, sometimes lasting more than an hour a time, reaching up to 200 feet (60 meters) high.
• 1910 – eruptions were so frequent that they happened once every 30 minutes.
• 1916 – activity at Geysir paused.
• 1935 – a man-made channel was created around the geyser, which quickly revived Geysir’s activity. Activity reduced as the channel became clogged with silica build-up.
• 1950 – another eruption took place, this time recorded on camera for the first time (see the video above).
• ~1980s – the channel was cleared, inducing activity again. This was helped with the addition of adding soap to Geysir.
• ~1990s – soap was sometimes used to induce eruptions in the decade, such as on Icelandic National Day. However, this was ceased after environmental concerns from adding soap.
• 2000 – an earthquake-induced Geysir into eruption activity again, sometimes up to eight times a day. This took around three years to reduce activity.
• 2016 – Geysir suddenly erupted again before reducing back down to nothing.

Research into the sinter (a form of silica that forms around geysers) around the geyser estimates that Geysir is around 10,000 years old and still has much steam coming off it today due to the high temperature of the water in the geyser.

Iceland’s Active Strokkur Geyser

Incredibly active geyser – erupts every 4-10 minutes

Spouts can reach as high as 130 feet (40 meters)

The Strokkur geyser is Iceland’s most active geyser, erupting once every 4-10 minutes. When Strokkur erupts, the steam can reach heights of 130 feet (40 meters) high. Even just at a depth of just over 20 meters, the water temperature reaches 130 degrees.

Strokkur is commonly the main reason for visiting the Geysir hot springs area due to its activity. It is a common picture point due to the height and frequency of its eruptions.

Iceland’s Geysir Geothermal and Hot Springs

Located in the southeast of Iceland, the Geysir geothermal and hot springs are an area of geyser activity. The attractions are hot streams and small/large geysers, of which one actively erupts every 4-10 minutes.

The area is filled with fumaroles, geysers of small and large, hot springs, mud pools, and steam, with a distinct smell of egg (sulfur) that propagates from the ground.

There are multiple geysers in this area, with three being the most notable:

1. The Great Geysir: As mentioned above, this is Iceland’s largest geyser and one of the largest in the world.
2. Strokkur geyser: This smaller geyser is located to the side of The Great Geysir and has the tendency to erupt once every 4-10 minutes, making this geyser’s activity one for tourism.
3. Little Geysir: This name is given to a very small geyser in the hot springs area that continuously bubbles and spurts.

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