Can we imagine a natural event capable to threaten the stability of the world’s economy, alter the climate as we know it, and even threaten the lives of millions of people? Volcanic super-eruptions, hundreds of times larger than volcanic eruptions witnessed by our interdependent human civilisation, are capable of such dangerous, widespread and diverse consequences. Despite their low probability of occurrence in relation to human life-span, super-eruptions increase in probability when transposed to the time-scales of civilizations.
The Campanian Ignimbrite (CI) erupted from the Phlegrean Fields on the Bay of Naples (Italy) 39,300 years ago, and it is considered the largest eruption of the Late Quaternary in Europe. Tephra ejected from the eruption blanketed over 3 million km2 from the eastern Mediterranean Sea to the Russian Plains. Recent studies indicate that the CI would have caused a volcanic winter, possibly lowering the temperature between 6-9 ºC in Eastern Europe and Northern Asia. It has been debated if the CI eruption, boosted by the coldest and driest Heinrich event, had an effect on the Middle to Upper Paleolithic transition altering the survival of the remaining Neanderthals in Europe.
Geological evidence indicates that the eruption had two phases and possibly had the following sequence:
1) a short, high-intensity Plinian explosive phase injecting gas and volcanic ash high into the stratosphere,
2) density-current transport affecting tephra dispersal and deposition near the source,
3) a caldera collapse, producing large and fast flows of hot gas and rocks (pyroclastic flow) that scaled mountain ridges of more than 1 km in height,
4) a significant portion of fine-grained material was lofted from the top of the propagating currents as co-ignimbrite plumes,
5) the finer ash of the co-ignimbrite phase dispersed downwind up to thousands of kilometres away from the eruption site.
We applied a novel computational approach to reconstruct, for the first time, the two phases of the Campanian Ignimbrite super-eruption. We used the FALL3D tephra dispersal model in conjunction with a downhill simplex inversion method (DSM) to infer values of the eruption source parameters. We compare the tephra dispersal and volume results from reconstructing the CI eruption as a two-phase event (Method 1), with those form conventional simplified characterization as a single-phase event (Method 2). Finally, simulation results are validated against two independent tephra deposits.
Simulation results for the tephra dispersal indicated that the eruption began with a short, high-intensity Plinian explosive phase (brown), followed by a longer co-ignimbrite phase (blue). The volume associated to the co-ignimbrite phase accounted for 75% of the total fallout volume (red).
The eruption lasted a total of 23 hours and blanketed a large region from the eastern Mediterranean Sea to the Russian Plains. The total erupted mass was 208 km3, a volume equivalent approximately to 8 Mount Everest.
The environmental stress that followed the CI eruption, aggravated by the precedential onset of the Heinrich Event 4, provides a link between this exceptional volcanic catastrophe and the extensively discussed Middle to Upper Palaeolithic transition. Settlements proximal to the source would have been abandoned in the immediate aftermath of the eruption due to tephra fallout and severe halogen acidification. Tephra fallout from our simulations, together with the attendant episode of Fenno-Scandinavian ice cap and peripheral tundra advance on land, reduced the area available for human settlement in Europe of up to 30% (ash fallout gap). We propose that after ecosystem recovery, several decades later, modern humans would have gravitated towards repopulating the tephra fallout gap rather that overcoming biogeographical frontiers (“Ebro frontier” model). Contrary to other theories, these results suggest that the CI eruption would have led to an instance of prolonged Neanderthal survival in South-Western Europe, especially in the Iberian Peninsula.
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