Map of the geoidal ondulations in Italy and the cross section Como-Otranto

Summary Astronomic and geodetic values of all observations made in Italy from 1868 to the present days are used to draw the geoidal ondulations-map in Italy.The geoidal ondulation along a cross section from Como to Otranto (for 1160 km length) is then traced.     

A comparative analysis of time–depth relationships derived from scientific ocean drilling expeditions

Marine Geophysical Research - Time–depth relationships (TDR) are required for correlating geological information from drill sites with seismic reflection profiles. Conventional...     

Sugli errori medi delle deviazioni della verticale

Riassunto Si determinano le precisioni con le quali possono venire osservate le deviazioni della verticale e si richiama l'attenzione su ciò quando si debbono interpretare le misure predette per prospezioni del sottosuolo.

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Summary Measuring the deflections of the plumb-line the attainable precision is determined, in particular to investigations for geophysical prospecting.

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Zusammenfassung Es wird für die Bestimmung der Lotabweichungen der erreichbare Genauigkeitsgrad untersucht, besonders im Hinblick auf Messungen zur Erforschung des Untergrundes.

     

Sulla equazione differenziale di Schweydar relativa alle maree terrestri

Riassunto Viene riportata in forma riassuntiva e con alcune varianti lo svolgimento teorico seguito dalloSchweydar, considerando per la rigidità e per la densità interne, funzioni della profondità affatto generali, per giungere alla equazione differenziale del sesto ordine a coefficienti polinomiali per la marea. Vengono inoltre ricordati gli studi diprey e dell'A. su questo argomento.

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Summary The theoretical solvings bySchweydar are resumed, with some variations, considering general formulas for rigidity and internal density, to reach the differential equation of sixth degree with polynomial coefficients, for the tides.Prey's studies on this subject, and of the Author, are mentioned.

     

Passive seismic prospecting in Venice historical center for impedance contrast mapping

Extensive passive seismic prospecting has been conducted in the historical center of Venice (North Italy) aimed to map subsoil impedance contrast. Venice represents an emblematic study site of the challenging characteristics that can be encountered in historical sites, both stratigraphic and logistical, limiting the application of common microzonation techniques. A total of 82 single station passive HVSR acquisitions and passive surface wave arrays analysis have been performed to estimate the main impedance contrasts of the first subsoil, capable of interaction in terms of resonance with the monumental buildings. The results of the geophysical analysis have been integrated with available stratigraphic information derived from published researches and from hundreds of boreholes stored in an institutional database. The results have been then analyzed by means of a geostatistical approach based on cokriging interpolation, which permitted to map the impedance contrast beneath the ancient historical center. The adopted interpolation algorithm permitted to map the impedance contrast with an integrated use of existing information based on HVSR acquisitions and stratigraphic data. The map of impedance contrast is congruent with the literature geo-engineering evidences such as subsidence and geological reconstructions. The achieved results open new perspectives for the use and analysis of passive seismic techniques in challenging environments as historical urban centers characterized by high subsoil heterogeneity. Moreover, an improved knowledge of the shallow stratigraphy would permit to shed light on the complex interactions between anthropic activities and geoenvironmental processes, including climate change that characterized the long history of Venice.     

HVSR technique as tool for thermal-basin characterization: a field example in N-E Italy

The Euganean thermal basin, located in the Eastern Po plain (Italy), is one of the most important thermal districts of Italy (Euganean–Berician Thermal District). The presence of hot water in the basin has brought about its exploitation over time. The thermal area has been known since the Roman Empire and is still of crucial interest for the profitable use of its hydro-geological resources. For these reasons the water cycle of the thermal area has been thoroughly studied, in particular with regard to its chemical and hydrogeological properties. The effects of well pumping, such as subsidence and water temperature steadiness, have been monitored over time. In the present work, the Horizontal to Vertical Spectral Ratio (HVSR) single station microtremor technique was applied as a non-invasive geophysical tool for the characterization of a part of the Euganean–Berician thermal district involving the municipalities of Abano and Montegrotto towns. This study represents the first correlation between the results from microtremor geophysical surveys and the thermal basin geological structure, including remote sensing data and thermal well information. More than 50 HVSR measurements from single stations were collected and analysed, in close correlation with the vast amount of available borehole logs, well exploitation data and SAR interferometry measurements collected for the monitoring of land subsidence induced by thermal water pumping. The aim of the work was to evaluate the suitability of the microtremor technique for the preliminary characterization of a thermal basin, in terms of resonance properties of the alluvial deposits covering the rocky bedrock, evaluated by means of HVSR methods. HVSR results were interpreted in terms of regional geological setting and hydrogeological properties of the subsoil. Our field results confirmed the existence of significant correlations between the resonance behaviour of the basin determined by the HVSR technique and the geological structures, suggesting that single station measurements are a promising tool for creating a rapid and preliminary non-invasive contribution to the characterization of the geothermal basin.     

Livellazione astronomica lungo il meridiano di Roma

Riassunto L'A. partendo dai risultati delle determinazioni astronomiche di latitudine e di azimut eseguite lungo il meridiano di Roma dal Reina dal 1898 al 1905 ed apportando ad esse le riduzioni al polo medio, in base ai risultati definitivi delle coordinate del polo per le epoche delle osservazioni, e le riduzioni al livello medio del mare, confronta i risultati trovati con gli omologhi geodetici relativi all'ellissoide di Bessel orientato a Genova e a Roma e all'ellissoide di Hayford orientato a Roma. Determina cosi le componenti meridiane ed astronomiche delle deviazioni delle verticali e con queste, dopo opportuna discussione, stabilisce il profilo del geoide dall'Isola di Ponza a Cortina d'Ampezzo per una lunghezza di oltre 700 Km, mettendo in luce una spiccata onda geoidica che raggiunge il massimo scostamento di circa 11 metri a Comacchio.

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Zusammenfassung Der Verfasser geht von den Ergebnissen der von Reina längs des Meridians von Rom in den Jahren 1898 bis 1905 ausgeführten Breite-und Azimut-Bestimmungen aus und fügt diesen Bestimmungen die Polreduktion zu auf Grund der endgültigen Ergebnisse für die zur Zeit der Beobachtungen geltenden Polarkoordinaten; es werden noch die Reduktionen auf Normal-Null berücksichtigt. Es werden weiter die ermittelten Daten mit den entsprechenden geodätischen Ergebnissen verglichen, welche sich auf das auf Genua und Rom orientierten Besselsche Ellipsoid beziehen. Es werden die meridianischen und orthodromischen Komponenten der Lot-abweichungen bestimmt und mit diesen das Profil des Geoids von der Insel Ponza bis Cortina d'Ampezzo in einer Länge von 700 Km. In dieser Erörterung wird eine deutliche geoidische Welle ersichtlich gemacht, die die grösste Abweichung von ungefâhr 11 m. in Comacchio erreicht.

     

Ventisette anni di attivita' gravimetrica internazionale

Riassunto L'A. riassume brevemente il contenuto dei Rapporti sulle misure di gravità che il Sen. Soler ha presentato nelle varie assemblee della Unione Geodetica e Geofisica Internazionale dal 1922 al 1939, soffermandosi particolarmente sull'ultimo, e richiama opportunamente i risultati geofisici conseguiti, in tale periodo di tempo, con la Bilancia di torsione in taluni Paesi aderenti alla U. G. G. I.

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Summary The Author sums up the contents of the Reports on the measurements of gravity which the late Sen. Soler has discussed in sundry meetings of the International Geodetic and Geophysical Union from 1922 to 1939, taking into special consideration the latest report. The Author examines the geophysical results obtained, during the above mentioned period, by means of the torsion balance in some countries that have joined the U. G. G. I.

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Zusammenfassung Der Verf. gibt eine kurze Zusammenfassung der Berichten über die Schwere-Messungen die von Herrn Sen. Soler in den Versammlungen der Intern. Geodätischen und Geophysikalischen Vereinigung seit 1922 bis 1939 vorgelegt wurden; in ausführlicher Weise erörtet er den letzten Bericht mit Erwähnung der geophysikalischen Ergebnisse welche in diesem letzten Zeitraum durch die Drehwaage in verschiedenen Ländern, die in der Int. Geod. und Geophys. Vereinigung teilnehmen, erhalten worden sind.

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Résumé L'Auteur donne un bref résumé sur l'ensemble des Rapports rélatifs aux mésures de gravité qui ont été présentés par le Sen. Soler dans les différents Assemblées de l'Union Géodésique et Géophysique Internationale entre 1922 et 1939, commentant particulièrement le dernier; ainsi, il rappelle aussi les résultats obtenus, dans la même periode de temps, avec la balance de torsion suivant les campagnes executées en différents pays adhérents à l'U. G. G. I.

     

Scostamenti normali dello sferoide terrestre dall'ellissoide di riferimento lungo allineamenti meridiani e paralleli

Riassunto L'A., completando alcuni suoi studi precedenti, ricava qui le espressioni normali per le deviazioni della verticale lungo meridiani e paralleli e quelle per gli scostamenti accennati nel titolo della presente Nota.

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Zusammenfassung Der Verfasser, um einige seiner vorigen Arbeiten zu ergänzen, gewinnt hier die üblichen Ausdrücke für die Lothabweichungen den Meridian-und Parallelkreisen eutlang und für die im Titel dieser Note erwähnten Abweichungen.

     

Tectonically driven deposition and landscape evolution within upland incised valleys: Ambra Valley fill,Pliocene–Pleistocene,Tuscany, Italy

Sedimentation in the upstream reaches of incised valleys is predominantly of alluvial origin and, in most cases, independent from relative sea‐level or lake‐level oscillations. Preserved facies distributions record the depositional response to a combination of allogenic factors, including tectonics, climate and landscape evolution. Tectonics drive fluvial aggradation and degradation through local changes in gradient, both longitudinal and transverse to the valley slope. This article deals with a Pliocene–Pleistocene fluvial valley fill developed in the north‐eastern shoulder of the Siena Basin (Northern Apennines, Italy). Evolution of the valley was not influenced by sea‐level or lake‐level changes and morphological and depositional evolution of valley resulted from extensional tectonics that gave rise to normal and oblique‐slip faults orthogonal and parallel to the valley axis. Data from both field observations and geophysical study are interpreted to develop a comprehensive tectono‐sedimentary model of coeval longitudinal and lateral tilting of the developing alluvial plain. Longitudinal tilting was generated by a transverse, upstream‐dipping normal fault that controlled the aggradation of fining‐upward strata sets. Upstream of the fault zone, valley back‐filling generated an architecture similar to that of classic, sea‐level‐controlled, coastal incised valleys. Downstream of the fault zone, valley down‐filling was related to an overwhelming sediment supply sourced and routed from the active fault zone itself. Lateral tilting was promoted by the activity of a fault oriented parallel to the valley axis, as well as by different offsets along near orthogonal faults. As a result, the valley trunk system experienced complex lateral shifts, which were governed by interacting fault‐generated subsidence and by the topographic confinement of progradational, flank‐sourced alluvial fans.