StrokkurAlong with the eponymous Geysir, this fountain of volcanically heated water that spouts up 1

StrokkurAlong with the eponymous Geysir, this fountain of volcanically heated water that spouts up 15-40 metres into the air every 4-8 minutes is one of Iceland’s most famous tourist sites. As the magma beneath cools, water percolating through the permeable basalt gets heated and rises back towards the surface. As it reaches the surface and cools, a form of silica opal called geyserite precipitates and can form a crust, blocking the vent until the pressure builds up and breaks through it, resulting in the next eruption. The other cause of pressurisation in geysers is cooler water capping the hotter water below, which heats up and boils, allowing the pressure to be released in the initial bubble seen bulging out in the slo mo video linked below.As the mass is expelled in the eruption, the pressure on the superheated (ie still liquid despite being at over 100 Celsius) water below goes down, allowing it to vaporise resulting in the steam eruption. The geyser needs some time to recharge its pressure, creating the gap between eruptions. The name comes from the Icelandic word for churn, which for those not familiar with the old ways was a pot in which milk and cream were beaten into butter.Strokkur has been active since at least 1789, when a quake is thought to have opened its conduit. It blew regularly until 1896 when it was de activated by another quake rechanneling the heated water or blocking the vent, and was unblocked by people in 1963, recreating a long gone tourist attraction.LozImage credit: Iurie Belegurschihttps://www.facebook.com/IurieBelegurschiPhotography?ref=ts&fref=tshttp://www.photovolcanica.com/VolcanoInfo/StrokkurGeyser/StrokkurGeyser.htmlSlow mo eruption on vimeo:http://vimeo.com/54156546 -- source link

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