A new hazard scenario at Vesuvius: deadly thermal impact of detached ash cloud surges in 79CE at Herculaneum

A new hazard scenario at Vesuvius has been revealed, highlighting the lethal thermal impact of detached ash cloud surges during the 79 CE eruption. Reflectance analysis on carbonized wood from ancient Herculaneum uncovered that the first pyroclastic density current (PDC) to enter the town was a short-lived, high-temperature ash cloud surge, reaching temperatures between 555-495 °C. This surge caused instant death while leaving minimal ash deposits, suggesting it detached from higher-concentration currents. Subsequent PDCs were cooler but more concentrated, with temperatures ranging from 350-315 °C. Charcoal emerged as the only reliable proxy to record these extreme thermal events, providing unprecedented insights into the eruption's real thermal impact. This finding underscores the underestimated hazard of hot detached ash cloud surges, which, despite their short duration, pose severe risks to both buildings and human life at Vesuvius and other volcanic regions.

Pensa, A., Giordano, G., Corrado, S., & Petrone, P. P. (2023). A new hazard scenario at Vesuvius: deadly thermal impact of detached ash cloud surges in 79CE at Herculaneum. Scientific Reports, 13(1). https://doi.org/10.1038/s41598-023-32623-3