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Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/2538

Authors: Ventura, G.*
Vilardo, G.*
Title: Emplacement mechanism of gravity flows inferred from high resolution Lidar data: the 1944 Somma-Vesuvius lava flow (Italy)
Title of journal: Geomorphology
Series/Report no.: 2007
Publisher: elsevier
Issue Date: 2007
DOI: 10.1016/j.geomorph.2007.06.005
Keywords: modeling
lava flows
Abstract: A Digital Terrain Model derived from high resolution Lidar data allow us to determine the morphometric and physical parameters of a lava flow erupted from the Somma-Vesuvius volcano in 1944. The downstream variation of the morphometric parameters, which include slope, aspect, range, thickness, width, and cross sectional area, is analyzed, and the changes in viscosity, velocity and flow rate are estimated. The aim is to recognize different flow surfaces, to reconstruct the flow kinematics, and to obtain information on the mechanism of emplacement. Results indicate that the 1944 lava can be divided in three sectors: a near vent sector (NVS) characterized by a toe-like surface, an intermediate sector (IS) with an ‘a‘ā-type, brittle surface, and a distal sector (DS) with a sheet-like, ductile surface. Lateral leveé and channels are lacking in NVS, whereas they are well developed in IS. In DS, leveés grow up moving away from the vent. Fold-like surfaces occur in NVS and DS and reveal local shortening processes due to a decrease in the slope of the substratum and to overflows from the main channel. IS and DS emplaced between 18 and 21 March 1944, whereas NVS emplaced on 19 March and partly overlaps IS. The morphometric and physical parameters indicate that IS moved in a ‘tube’-like regime, whereas DS emplaced in a ‘mobile crust’ regime. The IS to DS transition is marked by an increase in velocity and flow rate, and by a decrease in thickness, width, cross sectional area, and viscosity. This transition is due to an abrupt increase in the slope of the substratum. The estimated velocity values are in good agreement with the measurements carried out during the 1944 eruption. The analysis used here may be extended to other lava flows. Some gravity flows (debris/mud flows, floods, avalanches) have rheological properties and topography close to those of lavas, and the same effects can involve these flows. The approach used here may be useful for an evaluation of the hazard from gravity currents.
Appears in Collections:05.02.03. Volcanic eruptions
Papers Published / Papers in press

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