Photographer's Note

It is from The Great Geysir of Iceland, which first erupted in the 14th century, that the world's geysers take their name. It used to erupt every 60 minutes until the early 1900s when it became dormant. Earthquakes in June 2000 subsequently reawakened the giant and it now erupts approximately every 8 to 10 hours.

The second most famous geyser in Iceland is Strokkur, which erupts every 8 minutes throwing a column of water and steam to a height of 20 metres or so. There are also several other smaller ones.

The powerhouse of a geyser lies deep underground, where surface water seeps through fissures and collects in caverns. The temperature of the surrounding volcanic rock, at around 200 C, heats the trapped water, causing it to expand into steam and force its way up and out.

In the case of the Great Geysir, the depth of the column through which the steam rises is approximately 23 metres. The erupting water once reached a height of 60 metres, but today its maximum is only 10 metres.

Watching a geyser erupt, even a small one, is a fascinating sight. First the water starts to boil, then very quickly a bubble forms and bursts as the steam, hotter and lighter than the boiling water, forces its way skywards. When eruptions are particularly fierce one can sometimes feel the earth underfoot shaking slightly and hear distant rumbles. With the eruption comes a smell of sulphur, fortunately carried away on the wind!

The regularity of eruption can generally be timed to the minute. This is probably due to the time it takes for the expelled water to sink back down into the cavern and reheat to the necessary temperature. As it is the same amount of water that goes through the cycle, it takes the same amount of time for each cycle.

gmg, MarcoCertelli ha contrassegnato questa nota come utile

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Additional Photos by Lana Eddyshaw (Slana) Gold Star Critiquer/Silver Workshop Editor/Silver Note Writer [C: 60 W: 13 N: 42] (393)
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