Magma reservoir growth and ground deformation preceding the 79 CE Plinian eruption of Vesuvius

Ground deformation is not necessarily indicative of volcanic eruption style and size, according to finite element modelling of magma reservoir growth 300 years prior to the 79 CE eruption of Vesuvius constrained by petrological and stratigraphic data The 79 CE eruption of Vesuvius is the first documented Plinian eruption, also famous for the archaeological ruins of Pompeii and Herculaneum. Although much is known regarding the eruption dynamics and magma reservoir, little is known about the reservoir shape and growth, and related ground deformation. Numerical modelling by Finite Element Method was carried out, aimed at simulating the reservoir growth and ground deformation with respect to the reservoir shape (prolate, spherical, oblate) and magma overpressure. The modelling was tuned with volcanological, petrological and paleoenvironmental ground deformation constraints. Results indicate that the highest magma overpressure is achieved considering a prolate reservoir, making it as the most likely shape that led to eruption. Similar deformations but lower overpressures are obtained considering spherical and oblate reservoirs. These results demonstrate that ground deformation may not be indicative of eruption probability, style/size, and this has direct implications on surveillance at active explosive volcanoes.

Automated summary

Ground deformation may not accurately reflect the style and size of volcanic eruptions. Simulation results suggest that a prolate reservoir shape could lead to the highest magma overpressure, making it the most likely shape for eruption. This finding has important implications for monitoring active explosive volcanoes.