Abstract
The 39 ka Campanian Ignimbrite (CI) super-eruption was the largest volcanic eruption of the past 200 ka in Europe. Tephra deposits indicate two distinct plume forming phases, Plinian and co-ignimbrite, characteristic of many caldera-forming eruptions. Previous numerical studies have characterized the eruption as a single-phase event, potentially leading to inaccurate assessment of eruption dynamics. To reconstruct the volume, intensity, and duration of the tephra dispersal, we applied a computational inversion method that explicitly accounts for the Plinian and co-ignimbrite phases and for gravitational spreading of the umbrella cloud. To verify the consistency of our results, we performed an additional single-phase inversion using an independent thickness dataset. Our better-fitting two-phase model suggests a higher mass eruption rate than previous studies, and estimates that 3/4 of the total fallout volume is co-ignimbrite in origin. Gravitational spreading of the umbrella cloud dominates tephra transport only within the first hundred kilometres due to strong stratospheric winds in our best-fit wind model. Finally, tephra fallout impacts would have interrupted the westward migration of modern hominid groups in Europe, possibly supporting the hypothesis of prolonged Neanderthal survival in South-Western Europe during the Middle to Upper Palaeolithic transition.
Highlights
The 39 ka Campanian Ignimbrite (CI) super-eruption was the largest volcanic eruption of the past 200 ka in Europe
In order to evaluate the magnitude of each eruptive phase, it is critical to constrain their eruption dynamics and quantify optimal eruption source parameters (ESPs; i.e. erupted mass, mass flow rate, eruption duration, plume height and total grain size distribution) that best represent each phase of the eruption
We performed a model inversion to infer the ESPs that best represent the tephra deposits for each eruptive phase
Summary
The 39 ka Campanian Ignimbrite (CI) super-eruption was the largest volcanic eruption of the past 200 ka in Europe. In order to evaluate the magnitude of each eruptive phase, it is critical to constrain their eruption dynamics and quantify optimal eruption source parameters (ESPs; i.e. erupted mass, mass flow rate, eruption duration, plume height and total grain size distribution) that best represent each phase of the eruption In eruptions where both Plinian and co-ignimbrite sources (referred to as phases when separated in time during the eruption) have occurred, tephra deposits commonly have bimodal grain size distributions at individual sites[10]. Plumes from high-intensity eruptions can be injected high into the stratosphere, reaching a maximum column height and intruding laterally at neutral buoyancy level (NBL) as a gravity current (Fig. 1) This current can spread at velocities exceeding those of the surrounding winds, affecting tephra transport and deposition near the source[16,17]. Neglecting the gravitational spreading of the umbrella cloud in tephra dispersal simulations could misrepresent the interaction of the volcanic plume and the atmospheric wind field, especially for high-intensity eruptions and for proximal deposition of tephra[5]
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