An educational, but polluting, eruption

31.03.2021 - 15:02
Eldgosið í Geldingadölum í Fagradalsfjalli 23. mars 2021.
 Mynd: Birgir Þór Harðarson - RÚV
The Geldingadalir volcanic eruption in southwest Iceland is proving to be a fantastic learning opportunity, a prominent geophysicist tells RÚV, but it is also polluting rainwater nearby with high levels of fluorine pollution.

Tens of thousands of people have already visited the volcano and Easter weekend is expected to be especially busy, as Thursday, Friday, and Monday are public holidays in Iceland.

Police and search & rescue teams have decided to allow visitors between the hours of 06.00 and 18.00 throughout the long weekend, if weather conditions allow. The eruption site will be fully emptied of visitors by 22.00. The forecast is warm for the first half of the weekend but very cold for the second half, and especially windy on Saturday. 

Specialists from the Met Office and the earth sciences institute have measured fluorine levels in rainwater around the eruption and results from samples taken from puddles show a level of 80 milligrams per litre. The safe limit for drinking water is one milligram, for comparison. 

Andri Stefánsson, a professor of geochemistry at the University of Iceland, says around two tonnes of fluorine gas is emitted by the volcano per day; which, although it sounds like a lot, is dwarfed by the 40 to 50 tonnes emitted daily by the Fimmvörðuháls eruption of 2010. 

The pH value of water directly around the eruption site is as low as three, meaning it is a lot more acidic than normal rainwater, which has a pH of 5.5. The pH scale is one of magnitude, which means that pH 4 is ten-times more acidic than pH 5, and pH 3 is ten-times more acidic than pH 4. 

Geophysicist Páll Einarsson has been busy since the earthquake swarm first began but tells RÚV he is not tired yet. He says the eruption is proving extremely educational in understanding the nature and extent of the seismic activity that began with a series of earthquakes in December 2019. He says that series of events is far from over. 

Nobody accurately predicted how things would work out when the earthquakes first started late in 2019, according to Páll. The situation has developed more quickly and dramatically than people expected. The eruption at Geldingadalir is also in a remarkable location, as no eruption has happened there since the Ice Age. 

The eruption has relieved pressure in the earth’s crust and served to all-but stop the earthquakes in the area, Páll says—but adds its effect does not extend to the entire Reykjanes peninsula. Tension in the crust has not been relieved to the east of the peninsula, where history teaches that even larger quakes are still likely. 

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