Hydrological signals in height and gravity in northeastern Italy inferred from principal components analysis

This work describes a study of GPS heights, gravity and hydrological time series collected by stations located in northeastern Italy. During the last 12 years, changes in the long-term behaviors of the GPS heights and gravity time series are observed. In particular, starting in 2004–2005, a height increase is observed over the whole area. The temporal and spatial variability of these parameters has been studied as well as those of key hydrological variables, namely precipitation, hydrological balance and water table by using the Empirical Orthogonal Functions (EOF) analysis. The coupled variability between the GPS heights and the hydrological balance and precipitation data has been investigated by means of the Singular Value Decomposition (SVD) approach. Significant common patterns in the spatial and temporal variability of these parameters have been recognized. In particular, hydrology-induced variations are clearly observable starting in 2002–2003 in the southern part of the Po Plain for the longest time series, and from 2004–2005 over the whole area. These findings, obtained by means of purely mathematical approaches, are supported by sound physical interpretation suggesting that the climate-related fluctuations in the regional/local hydrological regime are one of the main contributors to the observed variations. A regional scale signal has been identified in the GPS station heights; it is characterized by the opposite behavior of the southern and northern stations in response to the hydrological forcing. At Medicina, in the southern Po Plain, the EOF analysis has shown a marked common signal between the GPS heights and the Superconducting Gravimeter (SG) data both over the long and the short period.     

Interpretation of crop growth patterns by means of NDVI‐time series in Zambia

A method to correlate crop production in Zambia to the yearly evolution of the Normalized Difference Vegetation Index (NDVI) is proposed. The method consists of the analysis of remote sensing data together with meteorological data and simulated crop production to obtain indicators of crop production. The accuracy of these indicators is assessed with statistical data.

The main objective was to assess whether the NDVI‐time series extracted from NOAA‐AVHRR‐images , having a pixel resolution of 73 km may give reliable information on crop production in Zambia where agricultural areas cover just 1% of the land area.

The mean NDVI‐value of several pixels, e.g. for one province or other administrative units, relates to the dominant type of vegetation in the area under consideration.

It is shown that the 7.3 km NDVI‐data give reliable indications on crop production in Zambia, when small areas (200–450 km² large ) are considered where agricultural land use is intensive. This implies that preliminary analysis is required to localize the agricultural areas. This has been done by means of high resolution satellite images i.e. LANDSAT‐MultiSpectral Scanner.

Consequently, the NDVI‐time series of the ‘agricultural ‘ pixels are used to calculate crop growth indicators which can be applied to assess the crop production.     

Does sediment resuspension by storms affect the fate of polychlorobiphenyls (PCBs) in the benthic food chain? Interactions between changes in POM characteristics, adsorption and absorption by the mussel Mytilus galloprovincialis

Environmental parameters and gross sedimentation rates (GSR) were monitored at a fixed site located in the Bay of Banyuls-sur-Mer (NW Mediterranean), between March 1997 and April 1998, together with the main biochemical characteristics of both sedimenting and sedimented particulate organic matter (POM). Three storms which occurred during this time period resulted in natural sediment resuspension. This is indicated by the corresponding increase in GSR and a decrease in the enzymatically hydrolysable amino acids/totally hydrolysable amino acids ratio (EHAA/THAA), within the sedimenting POM. Only the strongest storm resulted in (1) a transitory increase in fine-grained particles, (2) concomitant increases in organic carbon, carbohydrates, lipids and THAA, and (3) a decrease in the EHAA/THAA ratio in surficial sediments. For most of the assayed parameters, the values recorded after the December 1997 storm corresponded to extremes for the whole period under study. This emphasises the role of storms in controlling the characteristics of sedimented and sedimenting POM.Ten sediment types, with contrasting biochemical characteristics, were selected for experiments; these were based on the results of the monitoring survey and were used during adsorption and absorption experiments involving ¹⁴C tetrachlorobiphenyl (TCB). Adsorption rates differed significantly between the sediment types, but did not correlate with any of the assayed biochemical parameters. Absorption efficiency by the mussel Mytilus galloprovincialis also differed between the sediment types; it correlated positively with all the assayed biochemical parameters, except lipids. Comparison between the magnitudes of the increase in GSR, together with the decrease in absorption efficiency during resuspension events, suggests that resuspension tends to enhance the transfer of organic pollutants in the benthic food chain.     

Influence of soil consolidation and thermal expansion effects on height and gravity variations

The daily GPS height series of the Medicina station were analyzed for the period July 1996–September 2001. The station is located in the middle Po Plain on fine-grained alluvial deposits. A seasonal oscillation in the order of 18 mm (peak-to-peak amplitude) is present in the data. This crustal deformation has been modeled by including variations in the atmospheric, oceanic and hydrologic mass. The vertical positions can also be affected significantly by soil consolidation. Geotechnical parameters derived by in situ tests and laboratory analyses of the clayey soil collected at Medicina allowed the estimate of the soil settlement relevant to the seasonal oscillation of the surficial water table. Thermal expansion of the geodetic monument has to be taken into account in the case of high-precision vertical positioning. In this work models both for the soil consolidation and the thermal expansion effects are provided. The continuous gravity observations collected at Medicina by means of a superconducting gravimeter also exhibit a marked seasonal oscillation, which has been interpreted as the sum of loading and Newtonian attraction effects, as well as of the contribution due to soil consolidation. Especially the study concerning the soil consolidation effect has allowed a better insight on the seasonal vertical movements occurring at the Medicina station by providing quantitative information on soil behavior due to change of effective pressures. The results can be applied to those stations characterized by similar fine-grained soils and surficial hydrogeology.     

Pop-up landscapes: a new trigger to push up land value?

Through a qualitative analysis of pop-up landscapes on Philadelphia’s Delaware Waterfront, this paper examines how entrepreneurial urban actors, such as municipal officials, urban planning agencies, and landscape designers, strategically harness to catalyze investment. While pop-up landscapes have disrupted negative associations with the waterfront, providing a space for people to reimagine the city and playing an active role as an integrative public space, the paper argues that there are reasons to be skeptical about the long-term goals the pop-up landscapes serve, given the widespread focus on real estate-led development.     

Crystal structures of Ca-rich clinopyroxenes on the CaMgSi2O6-Mg2Si2O6 join

Summary The structural changes occurring in the clinopyroxenes with composition Di100, Di90En10 and Di80En20, due to the Ca-Mg substitution in the M2 site, have been studied. Evidence is given that with increasing Mg content a small percentage of the atoms converts from the M2 position to a new M2 position which is solely occupied by Mg. The maximum conversion of M2 to M2 found in this study is 7%. The closest parallel to the M2 geometry is found in the ZnSiO₃ pyroxene (C2/c). The presence of this new site causes significant changes in the tetrahedral configuration, because the M2 atoms are not bonded to 03. The intermediate compositions, Di90En10 and Di80En20, may be thought of as the coexistence of two structural models: diopside and ZnSiO₃ pyroxene (C2/c).

---

Kristallstrukturen Ca-reicher Klinopyroxene der CaMgSi₂O₆-Mg₂Si₂O₆-Reihe

Zusammenfassung Es wurden die strukturellen Änderungen von Klinopyroxenen der Zusammensetzungen Di100, Di90En10 und Di80En20, die durch den Mg-Ersatz für Ca verursacht werden, untersucht. Es zeigt sich, daß mit steigendem Mg-Gehalt ein kleiner Teil der Atome der M2-Position zu einer neuen M2-Position wechselt; diese wird ausschließlich durch Mg besetzt. Der größte in dieser Arbeit gefundene Übergang von M2 nach M2 beträgt ca. 7%. Die stärksten Parallelen zur Geometrie um M2 werden im Pyroxen ZnSiO₃ (C2/c) gefunden. Die Besetzung dieser neuen Position verursacht bedeutende Änderungen im Tetraederverband, da die M2-Atome nicht an O3 gebunden sind. Die Pyroxenstrukturen mit den intermediären Zusammensetzungen Di90En10 und Di80En20 können als Überlagerung zweier Modelle betrachtet werden: Diopsid und ZnSiO₃-Pyroxen (C2/c).

---

Abbreviations En Enstatite - Di Diopside - Hd Hedenbergite - Fs Ferrosilite - ClEn Clinoenstatite - Di100 pure diopside - Di90 Di90En10 (mol.-%) - Di80 Di80En20 - brg bridging With 6 Figures     

Constraints on the state of in situ effective stress and the mechanical behavior of ODP Leg 186 claystones in the Japan Trench forearc

Abstract The Japan Trench forearc offshore Honshu Island in northeast Japan, where the 130‐m.y.‐old Pacific oceanic plate is presently subducted, was drilled during the Ocean Drilling Program Leg 186. Results from mechanical and sedimentological studies of claystones recovered from Sites 1150 and 1151 in the overlying erosional forearc wedge are reported in the present study. Although many physical properties are similar in the seismic (Site 1150) and aseismic portion (Site 1151) of the shallow forearc, Site 1150 displayed a higher abundance of open fractures, two prominent fault zones and enigmatic pore fluid signatures in the claystones. The abundance of weak mineral phases, together with high smectite contents (from X‐ray diffraction), control the low friction coefficients of 0.33–0.39 of the claystones in ring‐shear experiments. Results from triaxial testing proposed overall low magnitudes of in situ effective vertical stress, with somewhat lower values at Site 1150 than at Site 1151. Similarly, samples from Site 1150 displayed slightly higher pore fluid pressures than those at Site 1151. The high sediment porosities, which are in part also a result of intact diatom tests (from scanning electron microscope), together with the anomalous fluid signatures and elevated pore fluid pressures, could very likely result from upward migration and influx of deep‐seated waters. Dewatering reactions at depth result in enhanced pore fluid pressure transients along out‐of‐sequence thrusts and consequently lower effective stress. At depths greater than that of Leg 186 drilling, elevated pressure–temperature conditions trigger mineral transformation and cementation, which result in increasing friction, unstable sliding and seismic rupture. Such earthquakes could have repeatedly disaggregated the consolidated claystone fabrics at the seismic site, and could be responsible for differences in yield strength and cementation when compared to the aseismic Site 1151.