[1] A stochastic model, named DOWNFLOW, is presented to forecast possible lava flow paths with the aim of hazard assessment and mitigation. The model relies on the fact that lava flow emplacement is, in many cases, controlled by topography. The potential inundation area of the flow is determined by considering a number of steepest paths over stochastic perturbations of the original topography. Since the code requires very short computational time and few input data the model proved to be a very useful tool to obtain realtime predictions during the initial phase of an eruption. The necessary topographic information can be obtained by photogrammetry, radar altimetry, or laser scanning techniques. DOWNFLOW has been successfully applied to a number of flows, including the September 2004 lava flow, where updated topographies were available.

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[1] Application of light detection and ranging (LIDAR) technology in volcanology has developed rapidly over the past few years, being extremely useful for the generation of high-spatial-resolution digital elevation models and for mapping eruption products. However, LIDAR can also be used to yield detailed information about the dynamics of lava movement, emplacement processes occuring across an active lava flow field, and the volumes involved. Here we present the results of a multitemporal airborne LIDAR survey flown to acquire data for an active flow field separated by time intervals ranging from 15 min to 25 h. Overflights were carried out over 2 d during the 2006 eruption of Mt. Etna, Italy, coincident with lava emission from three ephemeral vent zones to feed lava flow in six channels. In total 53 LIDAR images were collected, allowing us to track the volumetric evolution of the entire flow field with temporal resolutions as low as ∼15 min and at a spatial resolution of <1 m. This, together with accurate correction for systematic errors, finely tuned DEM-to-DEM coregistration and an accurate residual error assessment, permitted the quantification of the volumetric changes occuring across the flow field. We record a characteristic flow emplacement mode, whereby flow front advance and channel construction is fed by a series of volume pulses from the master vent. Volume pulses have a characteristic morphology represented by a wave that moves down the channel modifying existing channel-levee constructs across the proximal-medial zone and building new ones in the distal zone. Our high-resolution multitemporal LIDAR-derived DEMs allow calculation of the time-averaged discharge rates associated with such a pulsed flow emplacement regime, with errors under 1% for daily averaged values.

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The geomorphological and morphometric analysis of the sea floor topography surrounding the Aeolian Islands, South Tyrrhenian Sea, Italy, provides insights into the relationships between the volcanological evolution of the islands and their tectonic features. We constructed geomorphological maps of the submarine portions of the seven large edifices constituting the islands on the basis of a DEM with a 5 m resolution step. These maps include constructional and destructional landforms such as submarine volcanic vents located west of Lipari and north of Alicudi, and hummocky surfaces recognised north of Lipari and Salina. The latter landforms, together with the occurrence of large scars affecting the main edifices on land, suggest that sector collapses affected some islands. Geomorphological data indicate that the location of subaerial and submarine vents is strongly controlled by local tectonic structures striking WNW-ESE (Alicudi-Filicudi sector), NNW-SSE (Salina-Lipari-Vulcano sector) and NE-SW (Panarea-Stromboli sector). The islands can be divided Editorial responsibility: C. Kilburn into two groups on the basis of some morphometric parameters: a first group with a pancake-like shape, Dp/D (abrasion platform diameter/basal diameter) higher than 0.40 and H/D (total height/basal diameter) lower than 0.13, and a second group with a conical shape, characterised by Dp/D lower than 0.34 and H/D higher than 0.14. These ratios and other morphometric parameters reflect the different volcanological and structural evolution of the Aeolian Islands. The pancake-like shaped complexes have been created, in addition to their submarine stage, by extrusive and highly explosive activity, whereas the cone-shaped edifices have been characterised by effusive or moderate explosive activity.