Landslide databases in the Geological Surveys of Europe

Landslides are one of the most widespread geohazards in Europe, producing significant social and economic impacts. Rapid population growth in urban areas throughout many countries in Europe and extreme climatic scenarios can considerably increase landslide risk in the near future. Variability exists between European countries in both the statutory treatment of landslide risk and the use of official assessment guidelines. This suggests that a European Landslides Directive that provides a common legal framework for dealing with landslides is necessary. With this long-term goal in mind, this work analyzes the landslide databases from the Geological Surveys of Europe focusing on their interoperability and completeness. The same landslide classification could be used for the 849,543 landslide records from the Geological Surveys, from which 36% are slides, 10% are falls, 20% are flows, 11% are complex slides, and 24% either remain unclassified or correspond to another typology. Most of them are mapped with the same symbol at a scale of 1:25,000 or greater, providing the necessary information to elaborate European-scale susceptibility maps for each landslide type. A landslide density map was produced for the available records from the Geological Surveys (LANDEN map) showing, for the first time, 210,544 km² landslide-prone areas and 23,681 administrative areas where the Geological Surveys from Europe have recorded landslides. The comparison of this map with the European landslide susceptibility map (ELSUS 1000 v1) is successful for most of the territory (69.7%) showing certain variability between countries. This comparison also permitted the identification of 0.98 Mkm² (28.9%) of landslide-susceptible areas without records from the Geological Surveys, which have been used to evaluate the landslide database completeness. The estimated completeness of the landslide databases (LDBs) from the Geological Surveys is 17%, varying between 1 and 55%. This variability is due to the different landslide strategies adopted by each country. In some of them, landslide mapping is systematic; others only record damaging landslides, whereas in others, landslide maps are only available for certain regions or local areas. Moreover, in most of the countries, LDBs from the Geological Surveys co-exist with others owned by a variety of public institutions producing LDBs at variable scales and formats. Hence, a greater coordination effort should be made by all the institutions working in landslide mapping to increase data integration and harmonization.     

Comment on “Hydrodynamics of karst aquifers in metamorphic carbonate rocks: results from spring monitoring in the Apuan Alps (Tuscany,Italy)”: report published in Hydrogeology Journal (2023) 31:241–255, by Leonardo Piccini,Alessia Nannoni and Emilio Poggetti

Hydrogeology Journal -     

Micromechanically inspired investigation of cemented granular materials: part I—from X-ray micro tomography to measurable model variables

Acta Geotechnica - Cemented granular materials are abundant in nature and are often artificially produced. Their macroscopic behaviour is driven by small-scale material processes, which are...     

The RUSLE erosion index as a proxy indicator for debris flow susceptibility

Debris flows represent dangerous occurrences in many parts of the world. Several disasters are documented due to this type of fast-moving landslides; therefore, natural-hazard assessment of debris flows is crucial for safety of life and property. To this aim, much current work is being directed toward developing geotechnical-hydraulic models for the evaluation of debris flow susceptibility. A common base for such current models is parameterization of background predisposing and triggering factors such as inherent characteristics of geo-materials, topography, landscape and vegetation cover, rainfall regime, human activities, etc. which influence the occurrence of these processes on slopes. The same factors are also taken into account in soil erosion prediction models. Consequently, it seems worth investigating the effectiveness of the soil erosion index as debris flows susceptibility indicator. To this aim, a logistic regression analysis was carried out between the erosion index assessed by means of the Revised Universal Soil Loss Equation (RUSLE) model and the inventory of debris flows that have occurred in an area in Sicily (Southern Italy). Model assumptions were verified and validated by means of a series of statistical tools. Different possible scenarios were also evaluated by considering hypothetical changes in soil erosion rate under different rain erosivity conditions. Notwithstanding the rough approximations in model data collection, the outcomes appear encouraging.     

The influence of petrography,mineralogy and chemistry on burnability and reactivity of quicklime produced in Twin Shaft Regenerative (TSR) kilns from Neoarchean limestone (Transvaal Supergroup,South Africa)

Mineralogy and Petrology - This study evaluates the influence of chemical, mineralogical and petrographic features of the Neoarchean limestone from the Ouplaas Mine (Griqualand West, South Africa)...     

Morphologic resilience and depositional processes due to the rapid evolution of the submerged Sciara del Fuoco (Stromboli Island) after the December 2002 submarine slide and tsunami

In order to monitor the Stromboli submarine slope after the 30 December 2002 landslide and tsunami, repeated marine surveys were carried out offshore of Sciara del Fuoco. The morphological changes and depositional processes that brought to the gradual filling of the slide scar have been studied in detail. Thirteen surveys in a period of little more than 4 years provided a unique opportunity to reconstruct the morpho-sedimentary evolution of the submarine slope and its recovery after the mass-wasting event. The scar has been progressively filled with lava and volcanoclastic debris; in the first month and a half, the filling rate was very high due to the entrance of lava flows into the sea and to the morphological readjustment of the slope; in the following months/years the rate dramatically decreased when the eruptive vents moved upwards and the eruption finally stopped. After 4 years (February 2007) more than 40% of the scar was already filled. In early 2007, a new eruption occurred and a lava delta was constructed in the 2002 scar, influencing the natural readjustment of the slope; therefore, our reconstruction only encompasses the period between the 2002 and 2007 eruptions.The swath bathymetry reconstruction of geometry and volume of scar filling during the period 2002–2007 evidenced a punctuated and fast shift of depocenters and debris emplacement through avalanching processes. This process quickly obliterated the features produced by the 2002 tsunamigenic landslide so that a major question about the preservation potential of mass-wasting features on active volcanic flanks emerges.     

Three‐fold nature of coastal progradation during the Holocene eustatic highstand,Po Plain,Italy – close correspondence of stratal character with distribution patterns

Although general trends in transgressive to highstand sedimentary evolution of river‐mouth coastlines are well‐known, the details of the turnaround from retrogradational (typically estuarine) to aggradational–progradational (typically coastal/deltaic) stacking patterns are not fully resolved. This paper examines the middle to late Holocene eustatic highstand succession of the Po Delta: its stratigraphic architecture records a complex pattern of delta outbuilding and coastal progradation that followed eustatic stabilization, since around 7·7 cal kyr bp . Sedimentological, palaeoecological (benthic foraminifera, ostracods and molluscs) and compositional criteria were used to characterize depositional conditions and sediment‐dispersal pathways within a radiocarbon‐dated chronological framework. A three‐stage progradation history was reconstructed. First, as soon as eustasy stabilized (7·7 to 7·0 cal kyr bp ), rapid bay‐head delta progradation (ca 5 m year^?1), fed mostly by the Po River, took place in a mixed, freshwater and brackish estuarine environment. Second, a dominantly aggradational parasequence set of beach‐barrier deposits in the lower highstand systems tract (7·0 to 2·0 cal kyr bp ) records the development of a shallow, wave‐dominated coastal system fed alongshore, with elongated, modestly crescent beaches (ca 2·5 m year^?1). Third, in the last 2000 years, the development of faster accreting and more rapidly prograding (up to ca 15 m year^?1) Po delta lobes occurred into 30 m deep waters (upper highstand systems tract). This study documents the close correspondence of sediment character with stratal distribution patterns within the highstand systems tract. Remarkable changes in sediment characteristics, palaeoenvironments and direction of sediment transport occur across a surface named the ‘A–P surface’. This surface demarcates a major shift from dominantly aggradational (lower highstand systems tract) to fully progradational (upper highstand systems tract) parasequence stacking. In the Po system, this surface also reflects evolution from a wave‐dominated to river‐dominated deltaic system. Identifying the A–P surface through detailed palaeoecological and compositional data can help guide interpretation of highstand systems tracts in the rock record, especially where facies assemblages and their characteristic geometries are difficult to discern from physical sedimentary structures alone.     

Biotic forcing militates against river meandering in the modern Bonneville Basin of Utah

Biotic forcing on river meandering is a highly debated topic in sedimentology. Vegetation is assumed to hold a vital role on channel stability and sinuosity, for example through bank stabilization and pedogenic production of cohesive clays. However, statistically solid and causal relationships between vegetation density and river sinuosity remain largely untested in natural systems. This study investigates physical and biotic forcings on channel sinuosity in the Bonneville Basin of Utah (USA), an endorheic depression flanked by active fluvial networks (‘washes’) that display diverse vegetation density and channel‐planform style. By means of remote sensing and ground‐data collection, 58 washes are considered, 0·1 to 90 km² in surface area and drained by trunk channels <45 m wide and <1·2 m deep. Each wash is composed of a catchment basin connected downstream to an aggradational and distributive channel network. Statistically solid regressions highlight the primary roles played by base level and catchment size on fluvial morphogenesis. In contrast, no correlation is found between vegetation density and other parameters such as trunk‐channel width or surface area of the largest meander in a wash. Similarly, no statistical correlation exists between vegetation density and meander size or sinuosity index. Rather, larger and more sinuous meanders are invariably associated with lower vegetation density. These results are corroborated by field evidence showing that sparse vegetation promotes flow disturbance, channel branching and bar braiding instead of stabilizing sediment surfaces. Thus, river meandering is attributed to cohesion offered by mud retention within the endorheic basin, as well as discharge and stream‐power modulation along bifurcating and low‐gradient channel reaches. Hence, this work demonstrates how meandering‐channel patterns may arise from entirely physical forcings in the absence of vegetation.