Effects of eruption source parameter variation and meteorological dataset on tephra fallout hazard assessment: example from Vesuvius (Italy)

Abstract

In this study, using the tephra dispersal model HAZMAP, we investigate the effect of using different meteorological datasets and eruption source parameters on tephra fallout hazard assessment for a sub-Plinian eruption of Vesuvius, which is considered as a reference case for hazard assessment analysis. We analyze the effect of using different meteorological data, from: i) radio-sounding carried out at the meteorological station of Brindisi (Italy) between 1962 and 1976 and between 1996 and 2012, and at Pratica di Mare (Rome, Italy) between 1995 and 2013; ii) meteorological models of the National Oceanic and Atmospheric Administration (NOAA), and of the European Centre for Medium-Range Weather Forecasts (ECMWF). Furthermore, we consider the effects of perturbing reference eruptive source parameters. In particular, we vary the total mass, the total grain-size distribution, the column height, and the effective atmospheric diffusion coefficient to evaluate how these parameters affect the hazard probability maps. Moreover, the effect of the seasonal variation of the wind field and the effect of the rain on the deposit loading are considered. Results show that the parameter that mostly affects hazard maps is, as expected, the total erupted mass; furthermore, keeping constant the erupted mass, the most important control on hazard is due to the particle terminal settling velocity distribution which is a function of the total grain-size distribution, particle density and shape. Within the considered range variations, the hazard depends less on the use of different meteorological datasets, column height and effective diffusion coefficient.

Effect of particle volume fraction on the settling velocity of volcanic ash particles: insights from joint experimental and numerical simulations

“…Most numerical models of ash dispersal adopt a one-way coupling approach1314151617181920, an assumption justified in the dilute regions of the plume where ϕ p is less than 10 −6  31, in agreement with our above statements. However, depending on plume height, ϕ p may be 10 −5 –10 −6 in regions within a few hundreds of kilometres and up to 10 −3 more proximally293031.…”

“…This approach considers the settling of an individual particle in a still fluid, ignoring the presence of neighbouring particles. Similarly, the effect of particle volume fraction ( ϕ p ) on the settling velocity of individual (i.e., not aggregated) particles is not included in most numerical models of ash dispersal1314151617181920 which are mostly concerned with the fate of volcanic ash in the dilute, medium-distal regions of the plume. These models assume particles are only affected by the drag due to the local velocity of the carrier flow (one-way coupling), ignoring the effect of particle motion on the flow itself (two-way coupling) and inter-particle collisions (four-way coupling).…”

Modeling Eruption Source Parameters by Integrating Field, Ground‐Based, and Satellite‐Based Measurements: The Case of the 23 February 2013 Etna Paroxysm

“…α is internally calculated (details in Kaminski et al, 2005;Folch et al, 2016), whereas β is poorly constrained (Costa, Suzuki, et al, 2016), being calibrated based on best-fitting the field measurements. Characterizing the source term through FPlume implies uncertainties associated with the input parameters (see Macedonio et al, 2016).…”

Temporal models for the episodic volcanism of Campi Flegrei caldera (Italy) with uncertainty quantification

“…Bebbington [] compared trends and clustering of volcanic activity including many references on globally applicable cases. Thus, hazard estimates are often based only on the spatial distributions of specific hazardous actions conditional on the occurrence of a specific or an ensemble of volcanic events [e.g., Todesco et al , ; Costa et al , ; Neri et al , ; Macedonio et al , ] and ignore the temporal aspects. Long‐term temporal models are therefore necessary to provide a comprehensive assessment of hazard to be used for urban planning and risk reduction of the territory.…”