The 2016–2017 earthquake sequence in Central Italy: macroseismic survey and damage scenario through the EMS-98 intensity assessment

In this paper we describe the macroseismic effects produced by the long and destructive seismic sequence that hit Central Italy from 24 August 2016 to January 2017. Starting from the procedure adopted in the complex field survey, we discuss the characteristics of the building stock and its classification in terms of EMS-98 as well as the issues associated with the intensity assessment due to the evolution of damage caused by multiple shocks. As a result, macroseismic intensity for about 300 localities has been determined; however, most of the intensities assessed for the earthquakes following the first strong shock on 24 August 2016, represent the cumulative effect of damage during the sequence. The earthquake parameters computed from the macroseismic datasets are compared with the instrumental determinations in order to highlight critical issues related to the assessment of macroseismic parameters of strong earthquakes during a seismic sequence. The results also provide indications on how location and magnitude computation can be strongly biased when dealing with historical seismic sequences.Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC)Published2407–24314T. Sismicità dell'Italia1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto5SR TERREMOTI - Convenzioni derivanti dall'Accordo Quadro decennale INGV-DPCJCR Journa

Temporary dense seismic network during the 2016 Central Italy seismic emergency for microzonation studies

In August 2016, a magnitude 6.0 earthquake struck Central Italy, starting a devastating seismic sequence, aggravated by other two events of magnitude 5.9 and 6.5, respectively. After the first mainshock, four Italian institutions installed a dense temporary network of 50 seismic stations in an area of 260 km2. The network was registered in the International Federation of Digital Seismograph Networks with the code 3A and quoted with a Digital Object Identifier ( https://doi.org/10.13127/SD/ku7Xm12Yy9 ). Raw data were converted into the standard binary miniSEED format, and organized in a structured archive. Then, data quality and completeness were checked, and all the relevant information was used for creating the metadata volumes. Finally, the 99 Gb of continuous seismic data and metadata were uploaded into the INGV node of the European Integrated Data Archive repository. Their use was regulated by a Memorandum of Understanding between the institutions. After an embargo period, the data are now available for many different seismological studies.Publishedid 1825T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa

Valutare l'erosione del suolo mediante l'applicazione del modello RUSLE in ambiente GIS

Predicting GIS erosion by the application of RUSLE model in a GIS environment The increase in soil erosion risk due to the current climate change is a focal point in sustainable land management. Being able to predict this risk is fundamental for impact mitigation and soil resource conservation. The state-of-the-art in geo-information technologies (GIS, remote sensing and image analysis) allows to perform, in semi-automatic way, assessments and predictions based on the integration of theoretical models with advanced techniques of geospatial and geostatistical analysis. One of the most successful models worldwide utilised, such as the Revised Universal Soil Loss Equation (RUSLE), can be now easily applied at multiple spatial and temporal scales, i.e. from the single catchment up to the regional scale and from interannual to long-term scenarios, by using GIS-based tools

Susceptibility to Sea Cliff Failures at Cala Rossa Bay in Favignana Island (Italy)

Since the Roman Age and until the last century, an intense quarry activity took place at Favignana Island (Sicily, Italy) that significantly changed the morphology of the eastern part of the Island that is characterized by sea cliffs. This mining activity produced an extensive network of open air quarries, underground quarries and tunnels, locally named “Pirrere”, that are hosted into Pleistocene calcarenites. The sea cliffs of the eastern coast of Favignana Island were also influenced by the past mining activity and they are currently affected by diffused instabilities as proved by the wide block-size talus distributed all along the coast. A more detailed slope stability analysis was performed on a sea cliff located in the western sector of Cala Rossa Bay. To constrain such an analysis, engineering-geological field and remote surveys were carried out to reconstruct the geological setting as well as to characterize the mechanical properties of the rock mass. Finally a 3D model of the joints net was obtained. Based on geometrical and geomechanical joints features, a kinematic-compatibility analysis for rock landslide mechanisms (i.e. planar sliding, wedge sliding and toppling) allowed to identify 78 rock blocks particularly prone to failure. Considering hydrostatic pressure related to joints saturation condition as well as pseudostatic forces due to earthquake, 12 hazard scenarios were considered as reliable for the sea cliff area. The obtained results demonstrate that: (i) planar and wedge sliding are more suitable landslide mechanisms respect to toppling; (ii) the SE part shows higher susceptibility to failures; (iii) water pressures within joints play a more destabilizing action respect to earthquakes. Such an analysis represents a preliminary contribution to manage protection strategies for reducing the landslide risk in the touristic site of Cala Rossa bay and to preserve the unique heritage of the “Pirrere” quarries

Tyrrhenian sea level at 2000 BP: evidence from Roman age fish tanks and their geological calibration

Following the pioneering work of Schmiedt et al. (1972) on establishing the level of the Tyrrhenian Sea in Antiquity, a number of studies have examined this evidence from Roman Period fish tanks but with significantly different outcomes due primarily to different interpretations of the functional level of these pools at the time of their construction. As part of a longer term project to understand the causes of sea-level change around the Italian coast, we have reexamined and resurveyed 12 well-documented fish tanks, all based on the same construction principles, from the Tyrrhenian coast (between Formia and Orbetello) for which it can be established that they were in open contact with the sea at the time of operation. The structural features that tidally control the exchange of water used to define the ancient local sea level are identified as the channel thresholds, the sluice gate and sliding post positions, and the lowest level crepido. These are consistent for all the tanks examined, permitting the local sea-level change over the past 2000 years to be established at each location with a precision of ± 20 cm and against which other coastal archaeological features can be calibrated. We conclude that published local sea levels that are based on the present-day elevations of the foundations of protective walls constructed around the tanks and lie ~ 50 cm above our inferred levels are inconsistent with the successful functioning of the water exchange and have to be rejected. In one case, for Santa Liberata, we have been able to calibrate our interpretation against sedimentary evidence from the nearby Orbetello Lagoon that confirm our interpretation of the functional control level of the tanks and we conclude that the accuracy of our local sea levels is also ± 20 cm. The causes of sea-level change along this section of the coast are several, including land motion driven by tectonic and glacio-isostatic processes and any change in ocean volume. The individual estimates for the observed local sea levels range from − 0.9 to − 1.5 m with a mean value of − 1.22 ± 0.20 m. These values show that the spatial variability of the local levels is small and consistent with model-inferences of the glacio-isostatic process that indicate near-constant contributions for this section of coast and with tectonic inference from the elevations of the Last Interglacial shoreline.This research was initially funded by INGV (1998) and the Italian National Research Council (CNR-Agenzia 2000). Further studies have beneftted from funds by the Italian Ministry of Education, University and Research within the National Research program (PRIN 2006; 2011–2013, Vector and RITMARE projects), ENEA, and the Australian National University

Carta dell'erosione del suolo del Lazio meridionale

The present work was aimed to test the operability of the RUSLE prediction model, on the basis of available data, in combination with different interpolation methods in the area of southern Lazio (central Italy). The work was based on published rainfall, soil, land-cover and elevation data archives and on a quick supplementary soil sampling survey. The RUSLE factors were computed by means of different correlation formulae and algorithms. Despite the lack of information data, the obtained soil erosion map can provide a useful reference frame of the soil loss potential for regional planning purposes

Landslide monitoring at the Cala Rossa Sea Cliff (Favignana Island, Sicily)

Favignana Island (Sicily, Italy) is a historical and environmental attraction site frequented by tourists especially during the long warm season of the year. Over several centuries the sea cliffs constituted by calcareous sandstone cropping out in the east side of the island have been exploited for the production of building stone. Currently, the quarries used for the rock extraction as well as the natural cliffs are undergoing extensive erosional and gravitational processes. Besides putting at risk the safety of the people attending the area, the widespread rock falls are likely to threaten sites of great historical and anthropological value that, once destroyed, can no longer be reconstructed. The rock mass quality assessment and slope displacement monitoring of cliffs were carried on to identify the most unstable areas providing a support to the local authorities in the implementation of effective and sustainable mitigation measures. If adequate measures will be taken in future, operators and users of the tourist circuit will have the opportunity to enjoy these amazing sites with a reduced risk

Relative sea level change in Olbia Gulf (Sardinia, Italy), a historically important Mediterranean harbour

Olbia Gulf, located in northeastern Sardinia, is bordered by granite, metamorphic rock, and limestones (Capo Figari and Tavolara Island). It has been an important merchant harbour for three thousand years. Tidal notches in limestone, considered one of the best sea level markers, are present between 5.1 and 8.6 m a.s.l. A fossil beach deposit on Tavolara Island is of Tyrrhenian age (MIS 5.5, 125 ka). Between 1999 and 2001, during the building of a new Olbia harbour tunnel, many shipwrecks hidden under recent fine sediments have been discovered. The archaeological excavation (380 x 20 m, to the surface of the carbonate bedrock at 4 m depth) was done by the Soprintendenza per i Beni Archeologici per le provincie di Sassari e Nuoro (Olbia branch). During the archaeological excavation campaign, thousands of ceramics, other materials which were not in situ, and 24 shipwrecks of different age and size were recovered. Eleven of these wrecks were sunk while they were still in the harbour during an attack by the Vandals in the middle of the fifth century. This attack determined the beginning of a sharp decline of Olbia, and gives a clear picture of one of the turning points of the Mediterranean cultural evolution: the end of the Roman Empire. Considering −1.4 m as the average altitude of the shipwrecks on the silty bottom of the Olbia Harbour and comparing this value with the predicted sea level curve from the Lambeck model calculated for northern Sardinia (−1 m ca. 1500 cal BP), it appears clear that the ships were at the margin of the harbour in water depth of less than 0.5 m. This confirms: a) the previous archaeological interpretation; and b) that the northern Sardinian coast was stable during the last millennia. Due to the tectonic stability of the coastal area, the evolution of the shoreline from the Bronze age (4 ka cal BP) up to 21.5 ka cal BP (LGM, last glacial maximum) is reconstructed

Effects of Anthropic and Ambient Vibrations on Archaeological Sites: The Case of the Circus Maximus in Rome

The vibration effects on the Torre della Moletta and the ruins of the Circus Maximus in Rome are analyzed in the framework of a preservation effort of this archaeological area. Thanks to its exceptional size, the Circus hosts many social events with large audience (pop-music, opera concerts, sport celebrations, etc.) every year, thus taking the structures under high anthropic and environmental stress. Recordings were completed before, during, and after the concert of a famous band, on 7 September 2019. Data were analyzed, both in time and frequency domains. The experimental dynamic recordings were coupled with a surface waves test and single-station ambient vibration recordings, which were useful for the geotechnical characterization of the soil. The results pointed out the differences in amplitudes but also in terms of frequency content of the recorded velocities during the concert with respect to before and after it. The maximum velocities recorded at various locations were almost similar to the limit values suggested by codes. The dynamic behavior of the ground and the structures is influenced by the presence of buried structures