The ITalian ACcelerometric Archive (ITACA): processing of strong-motion data

The Italian strong-motion database was created during a joint project between Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italian Institute for Geophysics and Vulcanology) and Dipartimento della Protezione Civile (DPC, Italian Civil Protection). The aim of the project was the collection, homogenization and distribution of strong motion data acquired in Italy in the period 1972–2004 by different institutions, namely Ente Nazionale per l’Energia Elettrica (ENEL, Italian electricity company), Ente per le Nuove tecnologie, l’Energia e l’Ambiente (ENEA, Italian energy and environment organization) and DPC. Recently the strong-motion data relative to the 23th December 2009, Parma (Mw = 5.4 and Mw = 4.9) and to the April 2009 L’Aquila sequences (13 earthquakes with 4.1 ≤ Mw ≤ 6.3) were included in the Italian Accelerometric Archive (ITACA) database (beta release). The database contains 7,038 waveforms from analog and digital instruments, generated by 1.019 earthquakes with magnitude up to 6.9 and can be accessed on-line at the web site . The strong motion data are provided in the unprocessed and processed versions. This article describes the steps followed to process the acceleration time series recorded by analogue and digital instruments. The procedures implemented involve: baseline removal, instrumental correction, band pass filtering with acausal filters, integration of the corrected acceleration in order to obtain velocity and displacement waveforms, computation of acceleration response spectra and strong motion parameters. This procedure is applied to each accelerogram and it is realised to preserve the low frequency content of the records.     

Tracing contamination sources through phenotypic characterization of Escherichia coli isolates from surface water and groundwater in an agro-ecosystem

The objective of this research was to evaluate the groundwater chemical and bacteriological quality in the Barranquita-Knutzen basin (Córdoba, Argentina). The main purpose was to trace contamination through the examination of bacteriological parameters and antibiotic resistance of Escherichia coli, relating them to surface water, hydrogeological features and land use. Thus, 40 water samples were collected. The major chemical components and bacterial indicators were determined and antibiotic resistance was analysed using standard methods. Multivariate factorial analysis showed that the first principal component (PC) reveals the process of water mineralization, while the second and the third PCs explain a low percentage of variance, but collect chemical constituents and total and faecal coliform bacteria, respectively, revealing specific contamination situations. The observed antibiotic resistance profiles of E. coli and their relation with the land uses revealed that the source of faecal contamination in water is mainly from animal residues.     

Neo-deterministic seismic hazard scenarios for India—a preventive tool for disaster mitigation

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reliable and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489–508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93–165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489–508, 2003): the computer codes were improved to better fit the need of producing realistic ground shaking maps and ground shaking scenarios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.     

Event and model dependent rainfall adjustments to improve discharge predictions

Most conceptual rainfall–runoff models use as input spatially averaged rainfall fields which are typically associated with significant errors that affect the model outcome. In this study, it was hypothesised that a simple spatially and temporally averaged event-dependent rainfall multiplier can account for errors in the rainfall input. The potentials and limitations of this lumped multiplier approach were explored by evaluating the effects of multipliers on the accuracy and precision of the predictive distributions. Parameter sets found to be behavioural across a range of different flood events were assumed to be a good representation of the catchment dynamics and were used to identify rainfall multipliers for each of the individual events. An effect of the parameter sets on identified multipliers was found; however, it was small compared to the differences between events. Accounting for event-dependent multipliers improved the reliability of the predictions. At the cost of a small decrease in precision, the distribution of identified multipliers for past events can be used to account for possible rainfall errors when predicting future events. By using behavioural parameter sets to identify rainfall multipliers, the method offers a simple and computationally efficient way to address rainfall errors in hydrological modelling.     

Sequence stratigraphy based on high-resolution seismic profiles in the late Pleistocene and Holocene deposits of the Venice area

The sequence-stratigraphic investigation by Very High-Resolution (VHR) seismic profiles allowed recognition of the detailed architecture of the late Pleistocene and Holocene succession of the Venice area. In this way deposits previously known by the analyses of scattered cores, mainly taken along the lagoon margin and the littoral strips, have been correlated at regional scale including the near offshore sector and the result has pointed out the lateral variability of the stratal architecture. Late Pleistocene deposits consist of an aggrading floodplain and fluvial channel fills accumulated during decreasing eustatic sea level, and they are coeval with offlapping forced regressive marine wedges in the Central Adriatic basin. The Holocene sequence is composed of three main seismic units separated by major stratal surfaces. Unit 1 (up to 9 m thick) is formed by channelized deposits separated by areas showing sub-horizontal and hummocky reflectors, and is bounded at the base by a surface that records prolonged conditions of subaerial exposure and at the top by a flatter surface resulting from erosion by marine processes. Deposits of Unit 1 are interpreted as estuarine and distributary channel fills, and back-barrier strata. Unit 2 is well distinguishable from Unit 1 only in the offshore area and at the barrier island bounding the Venice Lagoon, and is composed of a prograding marine wedge (up to 10 m thick) that interacts laterally with ebb tidal deltas. Unit 3 consists of a tidal channel complex and inlet deposits, which testify the evolution of the lagoon area. Tidal channels are entrenched in the lagoon mud flat (coeval with Units 1–2) and cut the Pleistocene–Holocene boundary in several places.Following current sequence-stratigraphic concepts, the Holocene sequence is composed of a paralic transgressive systems tract (TST) (Unit 1) overlying a sequence boundary (the Pleistocene–Holocene boundary) and overlain by a marine highstand systems tract (HST) (Unit 2) in seaward locations and by highstand lagoonal deposits landwards. TST and HST are separated by a downlap surface that is amalgamated with a wave ravinement surface in several places. Unit 3 is coeval with the upper part of Unit 2, and its development has been favoured by human interventions, which led to a transgression limited to the lagoon area.Local factors during the deposition, i.e. subsidence, sediment supply, physiography, and current/wave regimes, led to a significant lateral variability in the architecture of the Holocene sequence, as evidenced by the extreme thickness variation of the TST along both depositional strike and dip. The HST, instead, shows less pronounced strike variations in the stratal architecture. Also, present data clearly evidence that the human impact has a great relevance in influencing the late Holocene sedimentation.     

Is there a correlation between lithosphere structure and the statistical properties of seismicity?

The elastic parameters and the thickness of the lithospheric part of the mantle, the lid, are correlated with the seismicity of Italy and surrounding areas through the estimation of several statistical parameters. In particular, the intensity of the flow of seismic events, deprived of aftershocks, reveals concentrations associated with large gradients in the lithospheric thickness. The average depth of crustal shocks tends to be very shallow in areas of thin and soft (low shear-wave velocities) lid. The positive influence, probably reflecting the thermal state in the lithosphere, is very large in connection with the thin and soft lid and where strong gradients in lid thickness are observed, and is small in connection with a thick and hard lid (high shear-wave velocities).     

Mineralogy and petrology of the Polino Monticellite Calciocarbonatite (Central Italy)

Summary Two small diatremes, about 0.25 my old, cut through Liassic limestones about 1 km NNE of the village of Polino (Long. 12°50'54E-Lat. 42°35'34N; Central Italy).The material filling the larger diatreme is mainly composed of a tuffisite with abundant lapilli showing concentric structure. Both unaltered country-rocks and massive hypabyssal carbonatite occur in the tuffisite as angular clasts and blocks, from a few mm up to more than 1 m in diameter.The Polino rock occurs in a strongly-potassic igneous district (Umbria Latium Ultra-alkaline District) which comprises phonolitic pyroclastic rocks and very rare kamafugitic lavas.Massive carbonatite blocks have an average mode of 53% Sr-Ba-rich calcite, 23% Fe-monticellite, 9% Th-perovskite plus Ti-magnetite, 6% Cr-phlogopite, 6% forsteritic olivine, about 2% Zr-schorlomite and ca. 1% Si-CO-OH apatite. Perovskite, schorlom ite, and apatite form cognate phases, whereas olivine and phlogopite, often replaced by monticellite, occur as nodules and as discrete grains with compositions and deformation features typical of mantle xenocrysts found in alkali basalts and ultramafic rocks.High modal content of Ca-carbonate, high Sr, Ba and LREE contents of calcite, the presence of rare minerals peculiar to carbonatitic rocks and an essential amount of monticellite indicate classification of the Polino rock as a monticellite calciocarbonatite.The Polino rock represents a carbonatitic melt strongly contaminated by mantle-crystal debris. It displays unusual geochemical features having trace elements closer to those of the regional-associated kamafugitic rocks rather than to those of common carbonatites.

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Mineralogie und Petrologie des Monticellit-Calciokarbonatites von Polino, Mittelitalien

Zusammenfassung Zwei kleine, um 0.25 Millionen Jahre alte Diatreme durchschlugen liassische Kalkgesteine, ungefdhr 1 km NNE des Dorfes Polino (Long. 12°50'54E-Lat. 42°35'34N; Mittelitalien). Das Material, aus dem das größere Diatrem besteht, ist überwiegend Tuffisit mit häufigen Lapilli, die eine konzentrische Struktur zeigen. Sowohl nichtalterierte Nebengesteine, wie auch massive, hypabyssale Karbonatite treten im Tuffisit als eckige Klasten und Blöcke auf, mit einem Durchmesser von wenigen mm bis 1 m.Das Polino-Gestein tritt in einem sehr Kalium-reichen Vulkan-Distrikt (der Umbria-Latium Ultraalkaline Distrikt) auf, der aus phonolitischen Pyroklastika und untergeordnet aus kamafugitischen Laven aufgebaut ist.Massive Karbonatite bestehen im Durchschnitt aus 53% Sr-Ba-reichem Calcit, 23% Fe-Monticellit, 9% Th-Perovskit und Ti-Magnetit, 6% Cr-Phlogopit, 6% Fo-reichem Olivin, ungefdhr 2% Zr-Schorlomit und ca. 1 % Si-CO-OH-Apatit. Perovskit, Schorlo mit und Apatit bilden eine Mineralassoziation, während Olivin und Phlogopit, die häufig durch Monticellit verdrdngt sind, als Nodulen und Einzelkbrner auftreten. Letztere zeigen Zusammensetzungen und Deformationen wie sie für Mantel-Xenokristalle in Alkali-Basalten und ultramafischen Gesteinen typisch sind.Der hohe Modalgehalt an Ca-Karbonat, hohe Sr, Ba und LREE-Gehalte im Calcit, das Vorhandensein von besonders für Karbonatite außergewöhnlichen Mineralen und häufiger Monticellit sprechen für eine Klassifizierung des Polino-Gesteins als Monticellit-Calciokarbonatit.Das Polino-Gestein repräsentiert eine karbonatitische Schmelze, die von Mantelkristallen kontaminiert ist. Die außergewöhnliche Geochemie dieser Gesteine ist durch Spurenelemente, die eine engere Verwandtschaft zu den regional assoziierten Kamafugiten als zu üblichen Karbonatiten erkennen lassen, geprägt.