Geochemical ice-core constraints on the timing and climatic impact of Aniakchak II (1628 BCE) and Thera (Minoan) volcanic eruptions

Olive shrub buried on Therasia supports a mid-16th century BCE date for the Thera eruption

The precise date of the 2nd millennium BCE ("Minoan") eruption of Thera (Santorini) has long been a focus of controversy due to a discrepancy between archaeological and radiocarbon-based dating of materials from stratigraphic layers above and below tsunami, ash and pumice deposits resulting from the eruption. A critical, though controversial, piece of evidence has been four segments of a radiocarbon-dated olive tree branch, buried on Thera during the eruption. Here we report new radiocarbon evidence from an olive shrub found carbonized by the same eruption deposits on neighboring Therasia (Santorini). The Therasia olive shrub dates slightly younger than the previous olive branch. Calibrated results and growth increment counts indicate increased probabilities for a mid-16th century BCE date for the eruption, overlapping with multiple volcanic sulfate markers from ice core records.

Second Intermediate Period date for the Thera (Santorini) eruption and historical implications

The historical relevance of the Thera (Santorini) volcanic eruption is unclear because of major dating uncertainty. Long placed ~1500 BCE and during the Egyptian New Kingdom (starts ~1565–1540 BCE) by archaeologists, ¹⁴C pointed to dates ≥50–100 years earlier during the preceding Second Intermediate Period. Several decades of debate have followed with no clear resolution of the problem—despite wide recognition that this uncertainty undermines an ability to synchronize the civilizations of the eastern Mediterranean in the mid-second millennium BCE and write wider history. Recent work permits substantial progress. Volcanic CO₂ was often blamed for the discrepancy. However, comparison of ¹⁴C dates directly associated with the eruption from contemporary Aegean contexts—both on and remote from Thera—can now remove this caveat. In turn, using Bayesian analysis, a revised and substantially refined date range for the Thera eruption can be determined, both through the integration of the large ¹⁴C dataset relevant to the Thera eruption with the local stratigraphic sequence on Thera immediately prior to the eruption, and in conjunction with the wider stratigraphically-defined Aegean archaeological sequence from before to after the eruption. This enables a robust high-resolution dating for the eruption ~1606–1589 BCE (68.3% probability), ~1609–1560 BCE (95.4% probability). This dating clarifies long-disputed synchronizations between Aegean and East Mediterranean cultures, placing the eruption during the earlier and very different Second Intermediate Period with its Canaanite-Levantine dominated world-system. This gives an importantly altered cultural and historical context for the New Palace Period on Crete and the contemporary Shaft Grave era in southern Greece. In addition, the revised dating, and a current absence of southern Aegean chronological data placed soon afterwards, highlights a period of likely devastating regional eruption impact in the earlier-mid 16^th century BCE southern Aegean.