The <scp>ad</scp> 79 Vesuvius eruption revisited: Plinian and post-Plinian falls

The well-exposed Plinian fall deposit of the ad 79 Vesuvius eruption is herein divided into 12 lithostratigraphic units: seven units in the white pumice deposit and five units in the grey pumice deposit. These distinct units are distinguished by significant variations in grain size and the ratio of lithic to juvenile clasts, enabling us to reconstruct the highly fluctuating dynamics of the eruptive column during the Plinian phase of the ad 79 eruption with previously undetected detail. These characteristics allow their distributions around the vent to be mapped, showing that the plume fluctuated between 14 and 34 km in height, depositing 6.4 km 3 of tephra in 17 h. To broaden the scope of our investigation, we extended our research to encompass five lithic-rich fall layers that occurred after the Plinian phase, providing information on the dispersion and eruptive parameters of these late fallout phases. Post-Plinian sustained column pulses persisted for several tens of minutes, with the first pulse being the longest, lasting for 44 min. This initial pulse possibly facilitated the attempts made by numerous Pompeians to flee the city following the arrival of the first two weak pyroclastic density currents.