Historical geospatial database for landslide analysis: the Catalogue of Landslide OCcurrences in the Emilia-Romagna Region (CLOCkER)

A review of the content, structure, accuracy, and completeness of the Catalogue of Landslide OCcurrences in the Emilia-Romagna Region (CLOCkER) is presented. CLOCkER is a historical database, designed and developed for all types of landslides in the hilly-mountain area of the Emilia-Romagna section of the Northern Italian Apennines. Historical data have been gathered through a collection of numerous sources, including technical reports, historical archives, scientific literature, and newspapers. The information obtained, which has been evaluated to assess its temporal precision and spatial accuracy, has been recorded in a catalogue consisting of a Database Management System (DBMS) linked to a geographical information system (GIS) interface. The catalogue presently includes 14,416 records of documented landslide occurrences, dating from Middle Ages up to the present. The catalogue is associated with a landslide inventory, continuously updated by the Geological Survey of the Emilia-Romagna Region, where information on the shape, typology, and state of activity of more than 80,000 landslides is included. Our assessment of catalogue quality reveals a satisfactory spatial accuracy and a level of completeness comparable with the theoretical target proposed in the literature for complete inventories. Outputs indicate that CLOCkER can be a reference example useful for other regional historical landslide catalogues. Such reference datasets are useful for a wide range of landslide assessment purposes and can provide practical assistance for stakeholders involved in both scientific and technical fields, forming the basis for landslide temporal trend reconstruction that is essential for landslide hazard evaluation at different spatial-temporal scales. CLOCkER is open access, freely available online.     

Characterization of a landslide-triggered debris flow at a rainforest-covered mountain region in Brazil

Natural Hazards - Debris flows represent great hazard to humans due to their high destructive power. Understanding their hydrogeomorphic dynamics is fundamental in hazard assessment studies,...     

Self Interactions in Warm Dark Matter: A View from Cosmological Perturbation Theory

Astronomy Reports - We provide a short overview into Self Interacting Warm Dark Matter (SI-WDM) models from the context of Cosmological Perturbation Theory (CPT). The aim is to generalize...     

Structure and properties of the Adriatic crust in the central‐eastern Southern Alps (Italy) from local earthquake tomography

Structure and properties of the Adriatic crust were determined from local earthquake tomography around the Giudicarie fault zone (central‐eastern Southern Alps, Italy). Tomographic results, based on well‐suited 436 revised earthquakes (period 1994–2007), have a resolution comparable to the scale of regional geological domains and tectonic structures. The observed strong velocity anomalies correlate well with lithological variations corresponding to different geological domains (particularly magmatic complexes at depth) and with high fracturing and/or presence of fluids along active fault systems (South Giudicarie and Valsugana–Bassano del Grappa–Montello thrusts).     

Potential vorticity estimates of absolute velocities on the Ross Sea shelf

We analyze absolute velocities on the continental shelf off Cape Adare, in the western sector of the Ross Sea (Antarctica). Such a velocity field is here inferred by using a novel inverse method of absolute velocity determination, namely the tracer PV method, related to potential vorticities of temperature and salinity. This theoretical choice allows us to directly use in situ temperature and salinity data. Moreover, it avoids high-order derivatives, which can give large uncertainties that affect estimates made using previous approaches. The tracer PV method also allows us to separately estimate the steady and non-diffusive component and the unsteady and diffusive components of the flow. The western sector of the Ross Sea is characterized by a surface layer of Antarctic Surface Water over layers of Low Salinity Shelf Water and High Salinity Shelf Water, flowing northward with average velocities ～6–7 cm/s. At ～200 m depth an intrusion of warmer and saltier Circumpolar Deep Water is also evident in our data. The steady absolute velocities are in good agreement with those obtained from the classical Margules equation, in particular regarding the northward flux of the High Salinity Shelf Water. Furthermore, velocities due to diffusive processes and mesoscale activity are discussed. Finally, a steady “thermal” approximation is discussed; it allows for a qualitative check of the results by means of temperature horizontal sections only.     

Geophysical investigation of the Sandalp rock avalanche deposits

In the study of rock avalanche phenomena, numerical modelling makes use of back analyses of the rock avalanche propagation for calibration of the modelling assumptions and parameters. The back analyses require knowledge of the run-out area boundaries and the thickness distribution of the deposit. Geophysical methods can be applied to retrieve the thickness distribution, but, due to strong heterogeneities and logistic problems they are seldom applied. The aim of this work is to assess the potential of integrated geophysical methods to recognise and characterise a deposit created by two rock avalanches which occurred in the Sandalp valley (Switzerland) in 1996. The topography of the site before and after the rock avalanche is known and can be used as a benchmark. Resistivity tomography, seismic P-wave tomography, and active and passive surface wave analysis have been applied on several profiles deployed both on the rock avalanche deposit and in the surrounding area. Innovative approaches for surface wave analysis based on laterally constrained inversion and multimodal inversion have been applied to the data. A comparison of the results of the geophysical investigations with the topographic benchmark has shown the capability of the geophysical methods to locate the bottom of the deposit in the areas where the contrast with the host sediments properties is significant. In these areas, the deposit has higher resistivities and lower seismic velocities than the underlying materials. In the areas where the deposit is thicker and richer in fine-grained materials the geophysical parameters are not able to discriminate between the rock avalanche deposit and the underlying sediments. As a secondary task, the geophysical methods also allowed the bedrock pattern to be outlined.     

Lissajous trajectories for lunar global positioning and communication systems

This work proposes a Lunar Global Positioning System (LGPS) and a Lunar Global Communication System (LGCS) using two constellations of satellites on Lissajous trajectories around the collinear L ₁ and L ₂ libration points in the Earth–Moon system. This solution is compared against a Walker constellation around the Moon similar to the one used for the Global Positioning System (GPS) on the Earth to evaluate the main differences between the two cases and the advantages of adopting the Lissajous constellations. The problem is first studied using the Circular Restricted Three Body Problem to find out its main features. The study is then repeated with higher fidelity using a four-body model and higher-order reference trajectories to simulate the Earth-Moon-spacecraft dynamics more accurately. The LGPS performance is evaluated for both on-ground and in-flight users, and a visibility study for the LGCS is used to check that communication between opposite sides of the Moon is possible. The total ΔV required for the transfer trajectories from the Earth to the constellations and the trajectory control is calculated. Finally, the estimated propellant consumption and the total number of satellites for the Walker constellation and the Lissajous constellations is used as a performance index to compare the two proposed solutions.     

Sediment chemical contamination of a shallow water area close to the industrial zone of Porto Marghera (Venice Lagoon, Italy)

The industrial zone of Porto Marghera is one the most important "contaminated sites of national interest" (SIN) in Italy, being identified as an area of high environmental risk. The site includes a wide shallow water area of the Venice Lagoon extending toward the city of Venice, which was investigated in order to acquire information on the pollutant level and distribution. Grain-size, heavy metal, nutrient, and organic micropollutant concentrations were determined in the surface sediment layers (0-5 and 5-10 cm depths) of 51 sites. A generally low contamination was found, except for Hg concentration, which increases the toxicological risk in most of the sites of the area, according to the results of a comparison with Sediment Quality Guidelines. A heavy pollution fingerprint (Cd, Cu, Hg, Pb, and Zn up to 15.2, 257, 11.9, 248, and 3010 mg/kg d.w., respectively) was instead found near the Tresse Island, which is ascribed to the spill of pollutants from the contaminated sediment disposed therein. Grain-size and heavy metal profiles down to a depth of 40 cm in eight selected sites, finally show a probable decrease of the pollution affecting the area in recent years.     

Multiscale Magnetic Underdense Regions on the Solar Surface: Granular and Mesogranular Scales

The Sun is a non-equilibrium, dissipative system subject to an energy flow that originates in its core. Convective overshooting motions create temperature and velocity structures that show a temporal and spatial multiscale evolution. As a result, photospheric structures are generally considered to be a direct manifestation of convective plasma motions. The plasma flows in the photosphere govern the motion of single magnetic elements. These elements are arranged in typical patterns, which are observed as a variety of multiscale magnetic patterns. High-resolution magnetograms of the quiet solar surface revealed the presence of multiscale magnetic underdense regions in the solar photosphere, commonly called voids, which may be considered to be a signature of the underlying convective structure. The analysis of such patterns paves the way for the investigation of all turbulent convective scales, from granular to global. In order to address the question of magnetic structures driven by turbulent convection at granular and mesogranular scales, we used a voids-detection method. The computed distribution of void length scales shows an exponential behavior at scales between 2 and 10 Mm and the absence of features at mesogranular scales. The absence of preferred scales of organization in the 2?–?10 Mm range supports the multiscale nature of flows on the solar surface and the absence of a mesogranular convective scale.     

Use of Federal Sand for Beach Nourishment and Shore Protection Projects

Coastal shoreline protection and beach nourishment are significant issues for coastal states along the Atlantic and Gulf coasts. In some areas, there is a critical need to identify suitable sources of sand for possible use in public works projects for coastal protection. The continental shelf contains large resources of sand and gravel that could be used to support such projects. The U.S. Department of the Interior's (DOI) Minerals Management Service (MMS) provides policy direction and guidance for development of the resources located on the federal portion of the continental shelf. This article highlights the MMS's Sand Program, focusing on its cooperative resource and environmental studies with several coastal states, significant milestones and accomplishments, and anticipated activities in 1998 and beyond. Management of sand resources on the federal portion of the continental shelf has been made easier by a federal state partnership concept. Using this cooperative concept, joint projects are being conducted to investigate offshore sand resources, potential sites, extraction methods, and related environmental conditions. The MMS has procedures for negotiating sand agreements under the Outer Continental Shelf Lands Act (OCSLA) and ensuring that the resources are developed in an environ mentally sound manner. The authority to negotiate with project sponsors, an important recent change in the OCSLA, also resides with the MMS. This 1992 change in OCSLA facilitates the use of Outer Continental Shelf (OCS)resources for public projects. Further, the MMS is authorized to assess a fee based on the value of the resource and the public interest served. The MMS has worked with local sponsors and authorized the use of OCS sand for two projects. However, additional resource and environmental projects, as well as negotiated agreements, are anticipated within the near future with states and local governments along the Atlantic and Gulf coasts.