Showing papers by "Claudia Romagnoli published in 2008"

The Stromboli 2002 tsunamigenic submarine slide: Characteristics and possible failure mechanisms

Abstract: [1] On 30 December 2002, a major instability event, deeply involving the submarine slope, occurred on the Sciara del Fuoco, on the western flank of Stromboli volcano, in the Aeolian Islands. Tsunami waves with a maximum runup of over 10 m in Stromboli were generated, having a measurable impact as far as the Sicily coast. Just 10 months before the event, a multibeam bathymetry had been collected in the area down to 1000 m of depth. A repetition of the survey after the slide allowed the unique opportunity to verify the occurrence of a large submarine slide and to define volumes involved and morphology generated by the event, through the comparison of the preevent and postevent bathymetric grids. A morphological characterization of the slope before and after the submarine landslide is presented, showing how the preexisting features interacted with the slide event in controlling the instability. Mechanisms of the submarine failure are discussed on the basis of the geometrical characters of the landslide event, structural and stratigraphic setting of the submerged slope, and geotechnical considerations on the behavior of slope material.

Slope Failures Induced by the December 2002 Eruption at Stromboli Volcano

Abstract: We reconstruct the sequence of landslides that occurred soon after the beginning of the December 2002 eruption on the NW flank of Stromboli volcano. Landslides involved the northeastern part of the Sciara del Fuoco (SdF) slope, an old collapse scar filled by products of volcanic activity, producing tsunami waves that severely damaged the coast of the island of Stromboli. Volumes of the mass detached from the subaerial and submarine slope were quantified by comparing preslide and postslide slope surfaces obtained by aerophotogrammetric and bathymetric data, which also allowed, in conjunction with field observations and helicopter surveys, the reconstruction of geometry and kinematics of landslides. According to the reconstructed sequence, 2 days after the beginning of the eruption, the upper part of the NE sector of the SdF slope experienced major displacements (few tens of meters). Movements propagated downslope and affected the nearshore portion of the submerged slope without a rapid sliding of the displaced mass into the sea. The following hours were characterized by a progressive increase of deformations, localized along shear zones extending over two thirds of the subaerial slope. This phase proceeded until a submarine slide about 6 x 10 6 m 3 in volume occurred, causing a first tsunami wave. The subaerial mass delimited by the shear zones and unbuttressed at its foot, then slipped into the sea producing a second tsunami wave. The main landslide event (and the minor slumps which followed) removed a volume of about 10 x 10 6 m 3 of the infilling deposit, to a thickness of at least 65 m. Hypotheses were formulated on the mechanisms that controlled the different phases of the instability sequence. Since hydraulic and stress/strain conditions progressively changed during the slope evolution, the formulated mechanisms are also based on geotechnical analyses and considerations on the mechanical behavior of volcaniclastic materials. The process that led to the landslide events.