Performances of the Italian seismic network, 1985-2002: the hidden thing

Seismic data users and people managing a sesimic network are both interested in the potentiality of the data, with the difference that the former look at stability, the second at improvements. In this work we measure the performances of the Italian Telemetered Seismic Network in 1985-2002 by defining basic significant parameters and studying their evolution during the years. Then, we deal with the geological methods used to characterise or to plan a seismic station deployment in a few cases. Last, we define the gain of the network as the percentage of located earthquakes with respect to the total recorded earthquakes. By analysing the distribution of non-located ("missed") earthquakes, we suggest possible actions to take in order to increase the gain. Results show that completeness magnitude is 2.4 in the average over the analysed period, and it can be as low as 2.2 when we consider non-located earthquakes as well. Parameters such as the distance between an earthquake and the closest station, and the RMS location decrease with time, reflecting improvements in the location quality. Methods for geologic and seismological characterisation of a possible station site also proved to be effective. Finally, we represent the number of missed earthquakes at each station, showing that nine stations control more that 50% of all missed earthquakes, and suggesting areas in Italy where the network might be easily improved.Comment: 17 pages, 1 table, 11 figures. Submitted to Annals of Geophysic

Sensori di impatto per l’ambiente museale

Il problema della corretta conservazione delle collezioni d’arte e della gestione dell’ambiente museale è alquanto complesso, poiché coinvolge istanze diverse e talvolta antagoniste. Schematizzando, da un lato è necessario garantire la massima fruibilità delle opere, favorendone l’accessibilità ad un pubblico sempre più ampio e allestendo gli ambienti in modo da ottimizzare la visibilità dei manufatti ed il benessere dei visitatori; d’altro canto è indispensabile proteggere gli oggetti esposti dal degrado indotto dai fattori ambientali (luce, fluttuazioni in temperatura ed umidità, inquinanti atmosferici veicolati anche dal pubblico, etc. ), e creare condizioni ambientali idonee alla conservazione dei manufatti [ ]. La soluzione di compromesso è in genere tutt’altro che ovvia, poiché gli oggetti d’arte sono complessi e compositi, e le indicazioni per una loro corretta conservazione variano da caso a caso, secondo la tipologia dei materiali che li costituiscono. In molti casi le condizioni ambientali ideali per gli oggetti sono di fatto incompatibili con quelle più adeguate per il pubblico, sia in termini di illuminazione che di microclima. Inoltre, è ormai assodato che l’alta frequenza di visitatori è associata ad un ulteriore incremento degli inquinanti atmosferici, (già presenti outdoor), senz’altro dannosi per i manufatti esposti

Raised marine terraces in the Northern Calabrian Arc (Southern Italy): a ~ 600 kyr-long geological record of regional uplift

The Sibari Plain in the Northeastern Calabrian Arc displays a well-developed suite of marine terraces. This paper deals with i) the identification and correlation of the terraces; ii) their age assignment and a tentative reconstruction of the uplift history of the area; iii) the relationships between terraces and major faults in the study area and between uplift in the Plain and pattern of Quaternary uplift throughout the Calabrian Arc. Identifying wavecut platforms and inner-edge fragments over a linear extent of ~ 100 km was achieved by photo interpretation, 1:25 000 scale map analyses and field survey. Morphological evidence led to the correlation of the identified fragments into five complete strandlines (numbered #1 to #5 lowest to highest), at elevations ranging from 60 m to ~ 650 m. Analysis of two parameters of the emerged platform-cliff systems, namely the platform-cliff ratio and the dissection percentage, further testifies that the two lowest terraces are strongly correlative. A 130 kyr AAR age of in situ fossil samples of Glycymeris collected at 114 m elevation within the deposit of Terrace #2 indicates a key correlation of T#2 with MIS 5.5 (the peak of the last interglacial, 124 kyr), i.e. an uplift rate of ~ 0.98 mm/yr for this strandline. The other four terraces have been tentatively associated with MIS 5.3, 7, 9 and 15. Geological observations independent of geochronological evidence provide consistent lower age boundaries for the terraces and supply further constraints to this interpretation. Investigating the relations between setting of the terraces and location of major tectonic structures in the region is suggestive of no recent activity of two previously recognized faults, the «Sangineto Line» and the «Corigliano-Rossano Line». Instead, some limited anomalies that affect the terraces are tentatively associated with the activity of the Castrovillari Fault. Therefore, sustained uplift has been the long-term dominant process of tectonic deformation in the study area over the past 124 kyr, possibly 600 kyr. Rates and history of uplift in the Sibari Plain are largely comparable with those observed in the whole Calabrian Arc, confirming that the uplift driving mechanism is deep-seated and closely connected to the Tyrrhenian subduction as already pointed out by several authors. Despite a dearth of Holocene raised paleoshorelines, it is suggested that similarly to what was observed only few tens of kilometres north and south of the Sibari Plain, the Late Pleistocene rise is still active today and that without Holocene uplift the Plain should have been far less developed and attractive for human settlement

Geology versus myth: the Holocene evolution of the Sybaris Plain

Historical accounts handed down the legend of the ancient Sybaris, defeated and submerged by the Crotoniates who diverted the River Crati on the town. This paper deals with the reconstruction of the Holocene evolution of the Sybaris Plain, through a number of geological and geomorphological observations. In particular, I found i) ∼1 m/yr horizontal coastal progradation rate since Greek times (2.4 kyr BP), possibly since Neolithic (7.0 kyr BP), mainly originated by active alluvial deposition and subordinately by regional uplift; ii) evidence of striking modifications in the surface hydrography of the plain during the last 2.5 kyr, with repeated fluvial captures of the Crati and Coscile rivers testified by ancient historians and geographers, recent maps and archeological accounts. In addition, datings and archeological information from 7 sites in the plain provided iii) ∼0.6 mm/yr mean uplift rate during the past 11.2 kyr, that confirms the substantial continuity of this regional process with upper Pleistocene; iv) local, high value of subsidence (0.5÷2.0 mm/yr) affecting the Sybaris main archeological area. Subsidence is not recorded before 4000 years BP and is caused by deposition of fine, highly compressible sediments at the transition between marine and continental environment; v) no evidence of a fault-induced contribution to the subsidence, whilst there is the grounded possibility that man-induced subsidence prevailed in the last century; vi) widespread active continental deposition in the area. Local rates of deposition are relatively lower (1.5 mm/yr) at sites where subsidence is not observed, and range between 2.5 mm/yr and 3.5 mm/yr in the main archeological area. There is also evidence of a clear decrease of the sedimentation following the Mid-Holocene flex of the fast trend of sea level rise. These data suggest that the Holocene evolution of the Sybaris Plain is due to the progressive eastward migration of the land-sea boundary, probably active since the Mid-Holocene (∼7.0 ka). Repeated floodings, regional uplift and relative sea-level changes produced the eastward expansion of the plain, subsidence locally slowed it down. Therefore, geology first allowed the creation of Sybaris, then caused its destruction

On the Development of a Generic Multi-Sensor Fusion Framework for Robust Odometry Estimation

In this work we review the design choices, the mathematical and software engineering techniques employed in the development of the ROAMFREE sensor fusion library, a general, open-source framework for pose tracking and sensor parameter self-calibration in mobile robotics. In ROAMFREE, a comprehensive logical sensor library allows to abstract from the actual sensor hardware and processing while preserving model accuracy thanks to a rich set of calibration parameters, such as biases, gains, distortion matrices and geometric placement dimensions. The modular formulation of the sensor fusion problem, which is based on state-of-the-art factor graph inference techniques, allows to handle arbitrary number of multi-rate sensors and to adapt to virtually any kind of mobile robot platform, such as Ackerman steering vehicles, quadrotor unmanned aerial vehicles, omni-directional mobile robots. Different solvers are available to target high-rate online pose tracking tasks and offline accurate trajectory smoothing and parameter calibration. The modularity, versatility and out-of-the-box functioning of the resulting framework came at the cost of an increased complexity of the software architecture, with respect to an ad-hoc implementation of a platform dependent sensor fusion algorithm, and required careful design of abstraction layers and decoupling interfaces between solvers, state variables representations and sensor error models. However, we review how a high level, clean, C++/Python API, as long as ROS interface nodes, hide the complexity of sensor fusion tasks to the end user, making ROAMFREE an ideal choice for new, and existing, mobile robot projects

Clues for a relation between rotational effects induced by the Mw6.3 2009 L’Aquila (Central Italy) earthquake and site and source effects

The Mw6.3 2009 L’Aquila earthquake produced an impressive number of rotational effects on vertically organized objects such as chimneys, pillars, capitals and gravestones. We present the dataset of such effects, that consists of 105 observations at 37 different sites and represents a compendium of earthquake-induced istances of rotational effects that is unprecedented in recent times. We find that the absolute majority of the reported effects was observed in the epicentral zone and that most of the observations are located where the MCS intensity is between 7 and 8-9. The evident asymmetry in the distribution of the rotational effects resembles the southeastward directivity of the macroseismic effects and highlights a significant convergence between rotations and damage. Finally, we perform some qualitative analyses to recognize and evaluate which *Manuscript Click here to download Manuscript: revised_text.doc 2 geological and seismological parameters can be significant contributors to local rotations. We find that surface geology and amplification of the seismic motion at each reported location strongly influence the occurrence and the nature of the earthquake-induced rotational effects. Conversely, the contribution of the pattern of slip distribution on the fault plane plays only a secondary role in enhancing the rotational motion at each site

Clues to the identification of a seismogenic source from environmental effects. The case of the 1905 Calabria (southern Italy) earthquake

The 8 September 1905 Calabria (Southern Italy) earthquake belongs to a peculiar family of highly destructive (I0=XI) seismic events, occurred at the dawning of the instrumental seismology, for which the location, geometry and size of the causative source are still substantially unconstrained. During the century elapsed since the earthquake, previous Authors identified three different epicenters that are more than 50 km apart and proposed magnitudes ranging from M≤6.2 to M=7.9. Even larger uncertainties were found when the geometry of the earthquake source was estimated. In this study, we constrain the magnitude, location and kinematics of the 1905 earthquake through the analysis of the remarkable environmental effects produced by the event (117 reviewed observations at 73 different localities throughout Calabria). The data used in our analysis include ground effects (landslides, rock falls and lateral spreads) and hydrological changes (streamflow variations, liquefaction, rise of water temperature and turbidity). To better define the magnitude of the event we use a number of empirical relations between seismic source parameters and distribution of ground effects and hydrological changes. In order to provide constraints to the location of the event and to the geometry of the source, we reproduce the coseismic static strain associated with different possible 1905 causative faults and compare its pattern to the documented streamflow changes. From the analysis of the seismically-induced environmental changes we find that: 1) the 1905 earthquake had a minimum magnitude M=6.7; 2) the event occurred in an offshore area west of the epicenters proposed by the historical seismic Catalogs; 3) it most likely occurred along a 100° N oriented normal fault with a left-lateral component, consistently with the seismotectonic setting of the area