A terrific volcanic blast lasting over a year seems to have convinced the suffering pagans of Iceland that their gods were dead and they’d be better off embracing Christianity, a new study dating the eruption postulates.
The eureka moment was conclusively dating a colossal eruption by the volcano named Eldgjá, based on information in ice cores and tree rings (which in turn is based on the postulation that “volcanic winters” interrupt tree growth).
The research was done by a team of scientists and historians led by the University of Cambridge, reporting in Climatic Change.
They then connect their finding with the most famous of Icelandic poems, the Voluspá (‘The prophecy of the seeress’), which is clearly describing a horrible eruption.
The Eldgjá erupted roughly a century after the island was first settled (insofar as we know). Vikings and Celts seeking new land to farm arrived from the North Atlantic in roughly the year 874, says the team.
Being newcomers, they presumably wouldn’t have been familiar with, let alone inured to, Iceland’s long-term geological pattern, which includes frequent volcanic upheaval. The Cambridge team and others now suspect their terror at the blast, and Thor’s inability to help, drove a mass conversion to Christianity – formally dated at about 999 C.E. (or a year later), which was within decades of the massive eruption.
It isn’t exactly contemporary, but the 12-century Landnámabók (“Book of Settlements”) says that among the earliest settlers in the area of the eruption was one Ásbjrn Reyrketilsson, follower of Thor.
Ankle-deep in England
When the Eldgjá blew in the 10th century, it didn’t produce some feeble burp of magma but a lava flood, which is when fissures in the crust keep pumping out more and more molten rock, engulfing the land. Typically this protracted flow is accompanied by toxic, corrosive gas emissions. In the case of Eldgjá, which means “fire gorge” in Icelandic, the magma spilled out of a rift 75 kilometers long.
A famous example of lava flood happened in Siberia, to an extent that dwarfs even this Icelandic drama. In Siberia the lava is believed to have flowed for a million years, creating the “Siberian Traps”, but that was 250 million years ago. Icelandic volcanism is prone to floods of thin lava, but they thankfully don’t last as long.
Even so, the last lava flow in 2015 darkened the skies as far away as Ireland, the team points out. In the vicinity, a flood of molten rock accompanied by sulfuric gas would have made life nigh-unbearable.
Eldgjá’s output may have covered only southern Iceland but the volcano emitted around 20 cubic kilometers of lava, which (the team calculates calculates) could “cover all of England up to the ankles.”
Based on ice cores, the team estimates that the eruption began in spring 939 and lasted through to autumn of 940. A year and a quarter, roughly.
“This places the eruption squarely within the experience of the first two or three generations of Iceland’s settlers,” says first author Dr Clive Oppenheimer of Cambridge’s Department of Geography, adding: some may have witnessed it.
Europe sees red
Eldgjá’s eruption would shroud the entire northern hemisphere. It created a haze of sulphurous dust across Europe. Records in Ireland, Germany and Italy of the time describe blood-red, dim sunshine. A volcanic winter in the northern hemisphere ensued, according to evidence seen in tree rings.
“From northern Europe to northern China, people experienced long, hard winters and severe spring-summer drought,” the team wrote. “Locust infestations and livestock mortalities occurred. Famine did not set in everywhere, but in the early 940s we read of starvation and vast mortality in parts of Germany, Iraq and China.”
And that’s far afield. In Iceland itself, the newcomers must have suffered very badly, which brings us to the poem.
No texts survive in Iceland itself about the eruption per se, yet the Voluspá seems to be describing that very thing: