Muenchow, J., A. Brenning, M. Richter, 2012. Geomorphic process rates of landslides along a humidity gradient in the tropical Andes. Geomorphology, 139-140, 271-284, doi:10.1016/j.geomorph.2011.10.029
Areas with high landslide activity and diversity were encountered in the tropical Andes of Southern Ecuador under... more Areas with high landslide activity and diversity were encountered in the tropical Andes of Southern Ecuador under contrasting, semi-arid to perhumid climatic conditions. The objective of this study was to determine and compare geomorphic process rates of shallow landslides along this remarkable humidity gradient and subject to different types of human-made and natural environmental changes. Geomorphic work, geomorphic power and landslide mobilization rate (LMR) were therefore calculated for shallow landslides in two study areas with two separate geological or land use-related subareas each. While landslide ages were known in the perhumid Reserva Biológica San Francisco (RBSF) area, only an approximation of the frequency of critical landslide-triggering rainfall events was available for the semi-arid Masamanaca area. Landslide volumes were estimated by volume–area scaling. Generalized additive models (GAMs) were used as landslide susceptibility models in order to analyze the relative importance of topography, and to downscale LMR values to a fine spatial resolution. LMR in the perhumid RBSF area ranged from ≈ 2 mm yr− 1 in the natural part of this area with tropical mountain rainforests to ≈ 5 mm yr− 1 in the human-influenced part. The semi-arid Masamanaca area, though subject to greater estimation uncertainties, displayed LMR on the order of ≈ 0.4 to 4 mm yr− 1 for shallow landslides. The results provide a basis for the spatially differentiated assessment of landscape evolution and degradation in an area with a close relation between landslide activity, natural vegetation succession and human land use.
2012 - Climats et cultures paléolithiques : quand la vallée devient frontière
by Marc Jarry
BRUXELLES L., JARRY M. – Climats et cultures paléolithiques : quand la vallée devient frontière. Nouveaux champs de la recherche archéologique, Archéopages, numéro spécial 10 ans de l'Institut, 2012, 85.
En 2002, dans un article de synthèse concernant le aléolithique de la région Toulousaine, Jacques Jaubert évoquait... more En 2002, dans un article de synthèse concernant le aléolithique de la région Toulousaine, Jacques Jaubert évoquait l'absence de vestige du Paléolithique supérieur. Effectivement, alors que les témoins des phases anciennes du Paléolithique sont bien représentés, les plus récentes sont pour ainsi dire absentes. Pour expliquer ce constat, il avait proposé trois explications possibles : 1) un biais dans la recherche : celle-ci aurait été insuffisante ou les sites ne seraient pas accessibles du fait, par exemple, d’un important recouvrement sédimentaire ; 2) la conservation différentielle : les terrains de cette période (et les sites qui vont avec) auraient été purgés par les phénomènes péri et post-glaciaires ; 3) la rareté effective d'établissements de plein air au Paléolithique supérieur dans certains contextes morphologiques. C'est à cette question que nous nous proposons de répondre ici, dans la continuité des travaux engagés sur cette problématique, en nous appuyant sur les résultats de dix ans d'archéologie préventive dans la vallée de la Garonne.
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Download (.pdf) Morphometry of scoria cones, and their relation to geodynamic setting: a DEM-based analysis
Fornaciai A., Favalli M., Karátson D., Tarquini S., Boschi E.
2012, J. Volcanol. Geoth. Res. 217-218.
The morphometry of a great number of scoria cones, belonging to volcanic fields of various geodynamic settings, has... more The morphometry of a great number of scoria cones, belonging to volcanic fields of various geodynamic settings, has been measured and analyzed, addressing the question whether there is a relation between the prevalent cone shape in a given field and the geodynamic setting of the field itself. Morphometric analysis was carried out on freely downloadable digital elevation models (DEMs). The accuracy of the used DEMs and the associated error in scoria cone morphometry were determined by cross-comparing high-resolution LIDAR-derived DEMs, USGS NED, TINITALY DEM and ASTER GDEM. The 10-m TINITALY/01 and USGS NED DEMs are proven to be suitable for scoria cone morphometry, whereas ASTER GDEM can be used reliably for cones with volume greater than 30×106 m3. According to a detailed morphometry of all scoria cones, we propose that the cones related to subductional setting show relatively higher values of Hco/Wco and lower values of Wcr/Wco than the cones related to extensional setting. The detected differences can be imputable to peculiar eruption dynamics resulting in slight but systematic changes in shape, and differences in lithological and sedimentological characteristics that govern post-eruptive erosion. To constrain the pathway of scoria cone erosion, the detected morphometric changes were also interpreted using a simple linear degradation model. Utilizing the obtained simulation results, the inferred initial cone base, and the age of scoria cones, we calculated a diffusion coefficient (K) for several dated cones, which are related to the prevalent climate. Our results, despite the high error associated, allow to assess the median K for all volcanic fields. Due to the complexity of the factors behind, it is not easy to understand if the prevalent shape characterizing a certain volcanic field is due mainly to sin-eruptive or post-eruptive mechanisms; however, our distinction between the two main geodynamic settings may be the first step to decipher these factors.
Dispersion index of topographic surfaces
Favalli M., Tarquini S., Fornaciai A., Boschi E.
2012, Geomorphology 153-154, 169-178
The dispersion index (dσ) of topography is introduced. This index is a geomorphic parameter which characterizes each... more The dispersion index (dσ) of topography is introduced. This index is a geomorphic parameter which characterizes each point of topography with respect to the stability/instability of the steepest descent path (SDP) originating from it. The procedure for calculating dσ is based on the assessment of SDP variations as the initial topography is also varied within a given elevation Δh, while a length scale L defines the maximum extent of the SDP. As a result, dσ can be derived for different ranges Δh and different bandwidths L. Since at each point the gravitational force would direct a surface flow along the SDP, dσ appears to have a strong influence on the behavior of gravity-driven mass flows, influencing local topographic widening, spreading or channelization. Considering Mount Etna (Italy) as a test case, we present maps of dσ for Δh=3 m and L=1, 2, 4 and 8 km, demonstrating also the relationship between the range Δh=3 m and Etnean lava flows. Focusing on the 2001 lava flow, we show that the presented maps of dσ, besides being a tool for viewing morphologies, have interesting applications for hazard assessment related to lava flows.
Release of a 10-m-resolution DEM for the Italian territory: Comparison with global-coverage DEMs and anaglyph-mode exploration via the web
Tarquini S., Vinci, S., Favalli M., Doumaz, F., Fornaciai A., Nannipieri, L.
2012, Computers & Geosciences 38, 168-170
The 10-m-resolution TINITALY/01 DEM (Tarquini et al., 2007) is compared with the two, coarserresolution,... more The 10-m-resolution TINITALY/01 DEM (Tarquini et al., 2007) is compared with the two, coarserresolution, global-coverage, spaceborne-based SRTM and ASTER DEMs and with a high-resolution, LIDAR-derived DEM. Afterwards, we presented a webGIS which allows to explore a 10-m-resolution anaglyph layer showing the landforms of the whole Italian territory in 3D. The webGIS (http://tinitaly. pi.ingv.it/) is open to the public, and can be used to carry out a preliminary analysis of landforms. The TINITALY/01 DEM is available for scientific purposes on the basis of a research agreement (see the above website or write to tinitaly@pi.ingv.it).
Using a Ground Based radar interferometer during emergency: the case of A3 motorway (Salerno Reggio-Calabria) treated by landslide
Chiara Del Ventisette, Emanuele Intrieri, Guido Luzi, and Nicola Casagli
The costal landslide from analogue experiments: perspectives and limitation
Chiara Del Ventisette, Teresa Nolesini, Sandro Moretti, Riccardo Fanti
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INSAR TIME-SERIES ANALYSIS FOR MANAGEMENT AND MITIGATION OF HYDROGEOLOGICAL RISK IN URBAN AREA
CIGNA F. , DEL VENTISETTE C. , LIGUORI V. , CASAGLI N.
Spaceborne SAR analysis for landslides mapping in the framework of the PREVIEW project
Gaia Righini (University of Firenze, Italy) ・ Chiara Del Ventisette (University of Firenze, Italy) ・ Mario Costantini (Telespazio, Italy) ・ Fabio Malvarosa (Telespazio, Italy) ・ Federico Minati (Telespazio, Italy)
Landslide inventory mapping by SAR interferometry is here described. Data from ERS and Envisat
satellites, with... more
Landslide inventory mapping by SAR interferometry is here described. Data from ERS and Envisat
satellites, with temporal range from 1995 to 2008, were used
to updated a landslide inventory map mainly concerning state
of activity and geometry. A test site was chosen in Lombardia
region (Italy) in the framework of the PREVIEW EU-GMES
FP6 project. Results gave evidence that SAR interferometry is
a powerful tool for landslides mapping due to its capability to
measure ground displacements with millimetric accuracy.
Case study on the updating of landslide inventory map with remote sensing data
G. Righini, C. Del Ventisette, N. Casagli and L. Lombardi
Fault array evolution in extensional basins: insights from statistical analysis of gravel deposits in the Cecina River (Tuscany, Italy)
Andrea Ciampalini, Ilaria Consoloni, Giovanni Sarti
Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany,... more
Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany, Italy) have been combined to unravel changes in the palaeo-drainage system. Data from 16 outcrops were collected and 6400 clasts described. Facies analysis, micro-palaeontology and macro-palaeontology and petrographic characteristics of the gravel deposits have highlighted the presence of three allostratigraphic units. Clast lithology is the main discriminator among these units. Cluster and principal component analyses of the 6400 clasts have improved understanding of the stratigraphy of the Lower Pleistocene deposits and constrain the re-routing of the lower palaeo-Cecina River from a supposedly south-east to north-west direction to the present east to west direction. Short rivers feeding small fan deltas represented by the oldest allostratigraphic units were abandoned in the Lower Pleistocene, when the re-routing of the Cecina River caused the capture of these streams. This evolution suggests a change in the tectonic regime of the area. The fan deltas developed on the hanging wall of normal faults sub-parallel to the coast; a change to a transtensile tectonic regime caused the deviation of the main river channel toward the present coast and the formation of a pull-apart basin, which is now exploited by the Cecina River. This study illustrates the value of lithological analyses of gravel deposits for understanding the tectonic evolution of an area.
Ground-based interferometry for monitoring an active rockslide in the Italian Alps
N. Casagli, C. Del Ventisette, G. Mannucci, L. La Rocca, A. Ballini, G. Antonello, J. Fortuny-Guasch, D. Tarchi and D. Leva
THE VAIONT LANDSLIDE FROM ANALOGUE AND NUMERICAL EXPERIMENTS
M. Bonini, N. Casagli, G. Corti, C. Del Ventisette, G. Gigli, F. Sani, S. Santoro
Understanding the breaking mechanism of landslides is fundamental to evaluate their hazard and to
predict the... more
Understanding the breaking mechanism of landslides is fundamental to evaluate their hazard and to
predict the energy release during the principal failure phase, the associated velocity and the runout
distance. The intensity of the landslide represents one of the most important parameter to hypothesize the
hazard scenario.
The Vaiont Landslide represents one of the most disastrous Italian landslides in term of the human life
loss. Since the catastrophic failure, numerous works have addressed the causes of the failure and the
origin of the anomalous velocities, which have been estonated to be of the order of 25-30 m/s. We aimed
answering some of these questions, and we integrated the results of some analogue and numerical
models. The 2-D numerical approach has provided useful data to understand the triggering mechanism,
while the analogue models are 3D simulations that helped understanding the internal deformation pattern
developed into the sliding rock mass.
DORIS PROJECT: THE EUROPEAN DOWNSTREAM SERVICE FOR LANDSLIDES AND SUBSIDENCE RISK MANAGEMENT
Fabiana Calò and DORIS Team
Space-borne SAR Analysis for Landslides Mapping in the Framework of the PREVIEW Project
Gaia Righini (University of Firenze, Italy) Chiara Del Ventisette (University of Firenze, Italy) ・ Mario Costantini (Telespazio, Italy) ・ Fabio Malvarosa (Telespazio, Italy) ・ Federico Minati (Telespazio, Italy)
Landslide inventory mapping by SAR
interferometry is here described. Data from ERS and Envisat
satellites,... more
Landslide inventory mapping by SAR
interferometry is here described. Data from ERS and Envisat
satellites, with temporal range from 1995 to 2008, were used
to updated a landslide inventory map mainly concerning state
of activity and geometry. A test site was chosen in Lombardia
region (Italy) in the framework of the PREVIEW EU-GMES
FP6 project. Results gave evidence that SAR interferometry is
a powerful tool for landslides mapping due to its capability to
measure ground displacements with millimetric accuracy.
DORIS downstream service: a support to civil defence autorithies in landslides and subsidence risk management
A Ciampalini, C Del Ventisette, S Moretti, M Manunta, F Calò, L Paglia, F Ardizzone, F Guzzetti, M Rossi, F Bellotti, D Colombo, T Strozzi, U Wegmuller, O Mora, and F Sanches.
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Seen by: Fault array evolution in extensional basins: insights from statistical analysis of gravel deposits in the Cecina River (Tuscany, Italy)
ANDREA CIAMPALINI, ILARIA CONSOLONI, GIOVANNI SARTI. Sedimentolgy, 58, 1895-1913
Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany,... more
Two statistical analyses of gravel clasts from the Lower Pleistocene deposits in the Lower Cecina Valley (Tuscany, Italy) have been combined to unravel changes in the palaeo-drainage system. Data from 16 outcrops were collected and 6400 clasts described. Facies analysis, micro-palaeontology and macro-palaeontology and petrographic characteristics of the gravel deposits have highlighted the presence of three allostratigraphic units. Clast lithology is the main discriminator among these units. Cluster and principal component analyses of the 6400 clasts have improved understanding of the stratigraphy of the Lower Pleistocene deposits and constrain the re-routing of the lower palaeo-Cecina River from a supposedly south-east to north-west direction to the present east to west direction. Short rivers feeding small fan deltas represented by the oldest allostratigraphic units were abandoned in the Lower Pleistocene, when the re-routing of the Cecina River caused the capture of these streams. This evolution suggests a change in the tectonic regime of the area. The fan deltas developed on the hanging wall of normal faults sub-parallel to the coast; a change to a transtensile tectonic regime caused the deviation of the main river channel toward the present coast and the formation of a pull-apart basin, which is now exploited by the Cecina River. This study illustrates the value of lithological analyses of gravel deposits for understanding the tectonic evolution of an area.
