Total grain size distribution of a mafic subplinian tephra, TB-2, from the 1986 Izu-Oshima eruption, Japan: An estimation based on a theoretical model of tephra dispersal

Mannen, Kazutaka

doi:10.1016/j.jvolgeores.2006.02.004

Cited by 37 publications

(22 citation statements)

References 18 publications

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“…The sorting value (σ Φ ) of the two estimated TGSDs is very similar (σ Φ =1.34±0.17 and σ Φ =1.36±0.08 for L2 and L3, respectively). The estimated TGSDs are also similar to those calculated for the mafic sub-plinian eruption of Izu-Oshima (Mannen 2006), the 1973 Strombolian eruption of Heimaey (Iceland; Self et al 1974) and the lava fountain activity at Etna during 2002and 2007(Andronico et al 2008a, whereas they are significantly coarser than the TGSDs of other mid-intensity eruptions like the 1968 and 1971 Cerro Negro (Rose et al 1973) The TGSD of the ash bed (A top ) was estimated by simply averaging the grain-size data of the available samples or by using the weighted average method (Bonadonna et al 2005). These two very simplistic methods were chosen due to the limited number of data available (eight samples with associated thickness measurement), mainly due to the difficulty of measuring a reliable thickness of the bed, being this often largely eroded or incomplete due its position at the top of the sequence.…”

Section: Total Grain-size Distributionsupporting

confidence: 77%

Dynamics and tephra dispersal of Violent Strombolian eruptions at Vesuvius: insights from field data, wind reconstruction and numerical simulation of the 1906 event

et al. 2015

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Mt. Vesuvius is one of the most studied volcanoes in the world and its proximity to an extremely populated area makes it also one of the most threatening. Violent Strombolian (VS) events have occurred in the most recent history of the volcano, and they are the type most likely to occur in case of reactivation of the volcano in the near future. In order to investigate the dynamics and hazard of this type of eruption, we performed new field and laboratory work and numerical simulations of plume dynamics, fallout and tephra dispersal associated with such eruptions. Attention was specifically focused on the 1906 eruption, a recent and well-studied VS event. Based on new field analyses and historical observations, we reconstructed the temporal evolution of eruption source conditions during the event. The reconstructed explosive phase of the eruption is inferred to have been 8 days long and characterized by two distinct stages: a former short and intense period with sustained convective plume fed by powerful lava fountains (20 h) followed by a prolonged and less intense period of ash emission (172 h). The total grain-size distributions for both phases, used as inputs to the model, were obtained by field work and laboratory analyses. Based on these new volcanological data and reconstruction of wind field direction and intensity, partially derived from historical sources, the 1906 event was numerically simulated and results compared to deposit distributions. The modelling outcomes for the ash emission phase provide a better agreement with the measured tephra mass load for a simulation run in which ash aggregation (described by the models of Cornell et al. J Volcanol Geotherm Res 17:89-109, 1983, and Biass et al. Nat Hazard Earth Syst Sci 14:2265-2287, 2014) is specifically taken into account, confirming the importance of this process during tephra dispersal. The aggregation model that best fits the simulated results to the measured ground loadings has 80 % of particles Φ≥4 that aggregate uniformly in the range Φ=−1 to 3. Two additional simulations of a VS event were carried out by using meteorological data of two specific periods to exemplify weather's potential on impacts of such eruptions, particularly tephra loading, on the surrounding areas. The model outcomes clearly highlight the major effects of differences in local meteorology on plume dynamics and ash dispersal and the key role of wind shear in determining the cumulative thickness of ground deposits. Results also show that, due to the long duration of this kind of eruption and the large variability in zonal winds at this latitude, ash dispersal and fallout from VS events at Vesuvius represent a probable hazard for all of the territory near Vesuvius, including the city of Naples, where cumulative tephra loadings might reach critical thresholds for roof collapse and infrastructure damage.

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Section: Total Grain-size Distributionsupporting

confidence: 77%

Dynamics and tephra dispersal of Violent Strombolian eruptions at Vesuvius: insights from field data, wind reconstruction and numerical simulation of the 1906 event

et al. 2015

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“…In fact, as mentioned above, the TGSD can be assessed by field analysis using statistical approaches (e.g. Bonadonna and Costa 2013; or by inverse modeling (Bonasia et al 2010;Mannen 2006) and the quality of this estimation strongly depends on the quantity and quality of the data (e.g. Barsotti et al 2010;Bonadonna et al 2015).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2016

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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.

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“…The 1986 Izu‐Oshima B fissure eruption simultaneously produced lava flows, a scoria cone and a subplinian tephra fall of basaltic andesite composition [ Endo et al , 1988; Nagaoka , 1988; Sumner , 1998]. The subplinian eruption consisted of a 12 to 16 km high column [ Mannen , 2006]. The umbrella spread scoria fall mainly eastward of the source vent.…”

Section: The 1986 Izu‐oshima B Eruption and Its Scoria Conementioning

confidence: 99%

“…To obtain the TSD of all pyroclasts issued from the fissure, the grain size distribution of fallout of the simultaneous subplinian plume [ Mannen , 2006] was integrated with the cone results of this study. The results are summarized in Table 1.…”

Section: Sampling and Grain Size Analysismentioning

confidence: 99%

“…In this study, we obtained the total grain size distribution (TSD) of the scoria cone to verify the process quantitatively. The TSDs of the subplinian fallout [ Mannen , 2006] and of the cone obtained in this study were used to calculate particle fractionation between the cone and subplinian plume. The particle fractionation as a function of particle size will be a constraint to simulate physics of eruption column.…”

Section: Introductionmentioning

confidence: 99%

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Formation of scoria cone during explosive eruption at Izu‐Oshima volcano, Japan

Mannen¹,

Ito²

2007

Geophysical Research Letters

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[1] Scoria cones have been regarded to be formed by accumulation of ballistic bombs ejected by mild eruptions. However, more recent geological investigations show that some scoria cones could be formed during explosive eruptions. Here, we demonstrate how the scoria cone of the 1986 Izu-Oshima eruption was formed during the explosive eruption. We measured particle fractionation of the cone and propose a theoretical model to explain the observation. The model considers lateral transport of particles by turbulent eddies; particles that reached characteristic column radius, L, are laterally transported to wL where they starts to free-fall. We obtained w = 1.2 and 2.5 for larger and smaller particles, respectively, which is consistent to the observation. In the model, extensive fallout takes place at the base of the column where it expands rapidly. We suggest that lateral particle projection and the rapid column expansion are the key processes to form the cones.

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Total grain size distribution of a mafic subplinian tephra, TB-2, from the 1986 Izu-Oshima eruption, Japan: An estimation based on a theoretical model of tephra dispersal

Cited by 37 publications

References 18 publications

Dynamics and tephra dispersal of Violent Strombolian eruptions at Vesuvius: insights from field data, wind reconstruction and numerical simulation of the 1906 event

Dynamics and tephra dispersal of Violent Strombolian eruptions at Vesuvius: insights from field data, wind reconstruction and numerical simulation of the 1906 event

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

Formation of scoria cone during explosive eruption at Izu‐Oshima volcano, Japan

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