05.08. Risk

We present the geomorphological map of the upper sector of the Roncovetro active landslide (Enza Valley, Emilia-Romagna, Italy). The 1:1500 scale map provides an accurate picture of the landslide in October 2014. The map is mainly based on the data collected during an airborne LiDAR survey. The capability of LiDAR to ‘penetrate’ the vegetation cover makes these data the most complete and accurate topographic dataset of this landslide. The map shows that the upper sector of the Roncovetro landslide consists of gravity- and water runoff-related forms. Gravitational features are linked to sliding and flowing movements that characterize the short- and long-term behaviour of the landslide. By comparing the 2014 LiDAR-Digital Elevation Model (DEM) with the 1973 DEM provided by the Emilia-Romagna Region, we calculated that 6.2 ± 0.8 × 105 m3 of material has moved from the top of the Roncovetro landslide in about 40 years.

Active volcanoes can generate multiple types of geological hazards. Besides syneruptive threats (e.g., lava, pyroclastic flows or ash fall), other adverse events such as landslides or lahars can occur at any time. To manage these threats efficiently, three key objectives must be jointly addressed: (1) improving prevention tools, through the collection and acquisition of data on hazards and risks, and its dissemination as maps and scenarios; (2) improving crisis management capabilities, based on monitoring and early warning systems, but also reliable communications systems; and (3) reducing people’s vulnerability and developing recovery and resilience capabilities after an event has occurred. The special issue “Approaches and methods to improve risk management in volcanic areas” presents research results focusing on these three objectives. It demonstrates the utility of addressing them jointly, and particularly examines the case of volcanoes where little knowledge is available. These results were presented at the conference Integrated Approaches for Volcanic Risk Management (Hohenheim University, Stuttgart, 11/12 September 2012) of the European MIAVITA (MItigate and Assess risk from Volcanic Impact on Terrain and human Activities) project.

The significant amounts of selenium(Se)emitted by volcanoesmay have important impact on human health due to the narrow range between nutrition requirement and toxic effects for living organisms upon Se exposure. Although soils play a key role in determining the level in food and water and thereby human health, little is known about the behaviour of Se in volcanic soils. In this work we evaluated the Se release during rainwater–soil interaction under controlled conditions using soils collected on the flanks of Etna volcano and synthetic rain. Seleniumconcentrations in soil leachate solutions displayed a spatial distribution, which cannot be explained by plume deposition, total Se soil concentrations or the presence of Fe oxides. Instead, Al compounds and to a minor extent SOM were identified as the active phases controlling the selenate mobilization during interaction with sulphate-containing rainwater. This shows the importance of soils as reactive interfaces. Selenium is mobilized when volcanic-derived acid rain interacts with poorly developed soils close to the crater. This geogenic process might influence the chemical composition of groundwater and as a result, human health.

The management of multiple hazards simultaneously impacting on a territory is a challenge for effective risk mitigation. This is particularly true on active volcanoes like Mt. Etna, characterized by effusive and explosive eruptions, often coupled with an intense seismic activity. This work aims at presenting the approach of the PANACEA project on the treatment of multi-hazards in terms of risk, which requires a common definition of the exposed elements and their vulnerability. Another aspect emerging from the recent and historical volcanic crises at Etna, is the occurrence of cascading effects and the problem of assessing their short-term interactions. Here we present a risk model taking into account a set of sequences of hazardous events which may result from a volcano unrest to possible impacts to some infrastructural elements. The outcomes of the project are intended to be a significant step towards a more comprehensive resilience to volcanic disasters, leading to a more safe society.

Although earthquakes are a threat in many countries and considerable resources have been invested in safety regulations, communities at risk often lack awareness and preparedness. Risk communication is a key tool for building resilient communities, raising awareness, and increasing preparedness. Over the past 2 decades, seismic risk communication has evolved significantly. This has led to a reorientation from a predominantly “one-way”, top-down communication model to the promotion of new models in which people, their needs, and their participation in disaster risk management are central elements. The 2015–2030 Sendai Framework recommendations, recent disaster experiences and research have highlighted that new models can improve communication effectiveness. In this paper, we critically explore this transition by conducting a scoping review (n=109 publications) of seismic risk communication in Europe. We analyse the approaches, messages, tools, and channels used for seismic risk communication and how they have changed over time. The results reveal that the stated goals of seismic risk communication are, in decreasing order, to share information, raise awareness, change behaviours/beliefs, and increase preparedness. Pupils, students, and citizens are the primary recipients of communication activities. Over the years, two trends have emerged. First, “two-way”, transdisciplinary and bottom-up communication models prevailed over the “one-way” model. Second, communication aimed more at promoting proactive behaviours than just informing the public. Face-to-face, hands-on activities, and serious games are key tools to engage with the public. The results also reveal the emerging role of social media to target different audiences/social groups. Strikingly, only one-fifth of the analysed publications explicitly build on or tests risk communication theories. Future research could focus on comparing practices across countries and risks (e.g., earthquakes and floods) and on innovating communication theories and methodologies, especially by incorporating the role of information technologies and social media.

The coastal carbonate Apulian aquifers, located in southern Italy, feed numerous coastal cold springs and constitute the main local source of high quality water. The group of Santa Cesarea springs constitutes the unique occurrence of thermal groundwater outflow, observed in partially submerged coastal caves. The spring water is rich of hydrogen sulfide; temperature ranges from 25 to 33 C°. For their properties, spring waters are used for spa activities from several decades. Hydrogeological spring conceptualisations proposed up now were not able to justify water geochemical peculiarities or were not completely confirmed up now. To reduce these uncertainties, a complex hydrogeological survey has been defined. Geological and structural surveys, chemical and isotopic groundwater analyses, spring and well discharge measurements, well loggings, multi-parameters spring automatized measurements, and cave explorations are ongoing. All available data have been used to improve the knowledge of groundwater flow system, including the valuable deep aquifer, the origin of the thermal waters, and to investigate the possibility of using low-enthalpy geothermal fluids to fulfil the thermal needs of the town of Santa Cesarea Terme.

The huge loss of lives and the destruction caused by the 2004 Indian Ocean tsunami dramatically showed the need for a reassessment of tsunami hazard and risk in coastal regions prone to this threat. It is known that many countries facing the Mediterranean basin have been affected by several tsunamis in the past, some of which were catastrophic over large areas. Our work aims to quantitatively address the problem of the tsunami hazard and risk assessment by means of numerical simulation of earthquake-induced tsunami scenarios. The work is part of a larger project, funded by the Italian Department for Civil Defense, whose main goal is the evaluation of the seismogenic potential and of the probability of occurrence of strong earthquakes in Italy. Here we show some preliminary results concerning the analysis of several simulated tsunami scenarios. On the basis of tsunami catalogues and seismogenic source databases, we selected a set of tectonic sources that, owing to their location and/or size, are believed to be especially hazardous for the Italian coasts. Once the geometrical parameters of the fault are defined (on the basis of geological and seismological evidence and constraints), we compute the coseismic vertical displacement of the seafloor, which represents the initial condition of the tsunami propagation problem. Then we solve the propagation equations (the wide used shallow-water equations) through a finite difference technique. The main outputs of a single run are the wavefields at desired times, useful to estimate the arrival times of the wavefronts, and the maximum water elevation field that gives at-glance information on the tsunami energy focusing during the whole propagation. Furthermore, for those stretches of coast that are particularly vulnerable (owing to high population density, presence of important infrastructures, etc.) we make a more detailed analysis of the wave impact. Among the tectonic sources we studied, the 365 AD Crete earthquake indeed represents a serious threat for the Italian coastlines facing the Ionian Sea, where we estimated a wave height exceeding 1-2 meters along hundreds of km of the coast. Furthermore, the first wavefront from this source is expected to reach the coasts of southern Italy in less than 1 hour from the origin time of the parent earthquake. This finding stresses the need for an especially early warning by the geophysical monitoring systems and by the Civil Defense structures.

Volcanic volatiles and aerosol emitted into the atmosphere ultimately fall on the Earth’s surface as wet or dry deposition, and they can influence the environment and the ecosystems at local and regional scales. Therefore, atmospheric deposition plays a key-role in the geochemical cycles, redistributing volcanogenic elements to the ground. For this reason, estimating the volcanogenic trace element fluxes from the atmosphere to the surface is necessary for a better knowledge of the environmental impact of the volcanic emissions. Nevertheless, from a literature review, we have recognized the scarcity of investigation on trace element deposition in the surroundings of active volcanoes. Here, we present a chemical characterization of bulk deposition around Mt. Etna, Italy, including both major and many trace elements. Bulk depositions were collected approximately fortnightly, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of the volcano. For most elements highest concentrations have been found close to the emission vent, confirming the prevailing volcanic contribution to rainwater composition close to the summit craters. Comparison with contemporaneously collected plume emissions shows that deposition processes produce no evident element-to-element fractionation. By contrast, comparison with whole rock composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/whole rock concentration ratios. Chemical concentrations in bulk deposition were used to estimate the deposition rates of a large suite of elements. Deposition rates for volatile trace elements like Se, As, and Cd range from 1.7, 1.2 and 0.9 µg m-2 day-1 nearby to the summit vents, to 0.5, 0.3, and 0.1 µg m-2 day-1 at the local background site on the upwind western sector.

In the framework of the EU project NEAREST, a new Tsunami Early Warning System (TEWS), able to operate in tsunami generation areas, was developed and installed in the Gulf of Cadiz. The TEWS is based on the abyssal station GEOSTAR, placed above a major tsunamigenic structure, and on three seismic centres of Portugal, Spain and Morocco. The core of the system is a tsunami detector installed onboard of GEOSTAR. The tsunami detector communicates with a surface buoy through a dual acoustic link. The buoy is connected to land stations via satellite link. The system was designed for near-field conditions and successfully operated from August 2007 to August 2008, 100 km SW of Cabo de Sao Vincente (Portugal). A new mission started on November 11th, 2009 in the same location. The tsunami detection is based either on pressure events either on seismic events. The bottom pressure data are analysed in real-time at the seafloor by a new tsunami detection algorithm, which can recognize tsunami waves as small as one centimetre. At the same time it was developed a new theoretical approach to account for tsunami generation in compressible water and in presence of a porous sediment. This model showed that hydro-acoustic waves, travelling much faster than the tsunami, are caused by the seafloor motion. These waves can propagate outside the generation area and are characterised by a modulation carrying valuable information on the seafloor motion, which can be recovered from their first arrival.

Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites..