De Vita, P.

Del Soldato, M.

Moretti, S.

Pazzi, V.

Segoni, S.

Tofani, V.

English

Florence Research

Geophysical Research AbstractsVol. 20, EGU2018-3311, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.Pyroclastic cover deposit thickness spatial modelling in peri-volcanic areasMatteo Del Soldato (1), Samuele Segoni (1), Veronica Pazzi (1), Pantaleone De Vita (2), Veronica Tofani (1), andSandro Moretti (1)(1) University of Florence, Earth Sciences, Italy (matteo.delsoldato@unifi.it), (2) Department of Earth Sciences, Environmentand Resources, Federico II University of Napoli, Complesso Universitario di Monte Sant’Angelo, Building L1, Via Cinthia -80126 Napoli, ItalyAsh-fall pyroclastic deposits mantle the peri-volcanic areas indifferently to the type of bedrock and depending onlyon the geomorphology of the area and the direction of prevailing wind during the eruption. The spatial distributionof the pyroclastic cover deposit thickness (PCDT) is a relevant factor for the slope instability in peri-volcanicmountain areas. The PCDT is considered a fundamental parameter in assessing landslide susceptibility as wellas volume potentially involved and inherent landslide run-out. In the international literature, different simple ormore complex models to predict spatial variability of PCDT are known. Nevertheless, peri-volcanic areas havepeculiar characteristics and several existing models result difficult to apply or they give back high overestimationor underestimation.Different existing methods were applied in the mountain ranges surrounding the Somma-Vesuvius volcano,southern Italy, to estimate the PCDT due to the high susceptibility of these areas to landslide. The poor resultsobtained by the application of known approaches led to develop a new empirical Slope Exponential PyroclasticThickness (SEPT) model. In particular, the SEPT is a simple method based on the exponential function of theslope gradient, the key geomorphological factor controlling the landslide triggering and evolution along theslope, and the initial total thickness of tephra-fall pyroclastic soil erupted by the Somma-Vesuvius volcano (z0),estimated by the sum of isopach maps derived by volcanological studies of the principal eruption products.The obtained distribution map of PCDT was validated by the comparison with about 300 field direct, e.g.penetrometer tests, and indirect, i.e. H/V approach, measurements of pyroclastic cover deposit thickness, as betteras possible distributed in the area of interest. The residuals among the modelled and the measured values werecalculated, and statistically analysed, by means of the maximum underestimation and overestimation, the standarddeviation and the root-mean square error, in order to estimate the efficiency of the resulting PCDT map.The result obtained by the SEPT approach designed for the mountain areas surrounding the Somma-Vesuviusvolcano can be considered applicable to the assessment of susceptibility and hazard of shallow landslides involvingthe ash-fall pyroclastic soil mantles and the estimation of volumes of potential unstable volcaniclastic materialin possible run-out scenarios. Moreover, results obtained advance the knowledge about mass wasting processesacting in ash-fall pyroclastic soil mantled slopes of the investigated areas as well as of other peri-volcanicmountain areas of the world.

Pyroclastic cover deposit thickness spatial modelling in peri-volcanic areas

https://flore.unifi.it/bitstream/2158/1144770/1/Del%20Soldato%20et%20al%20GRA%20vol%2020EGU%202018%20%282%29.pdf

Pyroclastic cover deposit thickness spatial modelling in peri-volcanic areas

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