2009年意大利中部阿奎拉地震DInSAR同震位移的有限断层反演

根据环境卫星Envisat和COSMO—SkyMed模型（为同震位错研究而首次设计的X波段反演干涉图）的DInSAR干涉图,确定了2009年4月6日阿奎拉Mw=6．3级地震时激发的断层几何形状及运动特征。我们的主震最佳拟合解为一个约16km长、12km宽的正断层,存在小的右旋分量,向西南倾斜47°,最大滑动约90cm。虽然地震位错可能只有1km深,但是断层面的上倾投影与标绘的帕加尼卡-南德米特里奥断层的北段相符合,在现场观察到了该断层地表破裂的迹线。该断层在现有震源目录中的缺失表明,需要对具体的地表和地下进行进一步的地质和地球物理勘测,以便对局部规模的地震危险性做出更准确的评估。     

Isotopic and element exchange during serpentinization and metasomatism at the Atlantis Massif (MAR 30°N): Insights from B and Sr isotope data

The Lost City hydrothermal system at the southern Atlantis Massif (Mid-Atlantic Ridge, 30°N) provides a natural laboratory for studying serpentinization processes, the temporal evolution of ultramafic-hosted hydrothermal systems, and alteration conditions during formation and emplacement of an oceanic core complex. Here we present B, O, and Sr isotope data to investigate fluid/rock interaction and mass transfer during detachment faulting and exhumation of lithospheric sequences within the Atlantis Massif. Our data indicate that extensive serpentinization was a seawater-dominated process that occurred predominately at temperatures of 150-250 °C and at high integrated W/R ratios that led to a marked boron enrichment (34-91 ppm). Boron removal from seawater during serpentinization is positively correlated with changes in δ¹¹B (11-16‰) but shows no correlation with O-isotope composition. Modeling indicates that B concentrations and isotope values of the serpentinites are controlled by transient temperature-pH conditions. In contrast to prior studies, we conclude that low-temperature marine weathering processes are insignificant for boron geochemistry of the Atlantis Massif serpentinites. Talc- and amphibole-rich fault rocks formed within a zone of detachment faulting at temperatures of approximately 270-350 °C and at low W/R ratios. Talc formation in ultramafic domains in the massif was subsequent to an early stage of serpentinization and was controlled by the access of Si-rich fluids derived through seawater-gabbro interactions. Replacement of serpentine by talc resulted in boron loss and significant lowering of δ¹¹B values (9-10‰), which we model as the product of progressive extraction of boron. Our study provides new constraints on the boron geochemical cycle at oceanic spreading ridges and suggests that serpentinization associated with ultramafic-hosted hydrothermal systems may have important implications for the behavior of boron in subduction zone settings.     

Correction to: Rip current hazard assessment on a sandy beach in Liguria,NW Mediterranean

Natural Hazards - The article was published showing the first two author names in the wrong order.     

Land use changes,torrent control works and sediment mining: effects on channel morphology and sediment flux,case study of the Reno River (Northern Italy)

As with most Italian rivers, the Reno River has a long history of human modification, related also to morphological changes of the lower Po River since Roman times, but in the last decades, significant land use changes in the headwaters, dam construction, torrent control works and extensive bed material mining have caused important channel morphology and sediment budget changes. In this paper, two main types of channel adjustment, riverbed incision and channel narrowing, are analysed. Riverbed degradation is discussed by comparing four different longitudinal profiles surveyed in 1928, 1951, 1970 and 1998 in the 120 km long reach upstream of the outlet. The analysis of channel narrowing is carried out by comparing a number of cross‐sections surveyed in different years across the same downstream reach. Field sediment transport measurements of seven major floods that occurred between 2003 and 2006 are compared with the bedload transport rates predicted by the most renowned equations. The current low bedload yield is discussed in terms of sediment supply limited conditions due to land use changes, erosion‐control works and extensive and out of control bed material mining that have affected the Reno during the last decades. Copyright © 2011 John Wiley & Sons, Ltd.     

Rip current hazard assessment on a sandy beach in Liguria,NW Mediterranean

Natural Hazards - Rip currents are one of the most significant environmental hazards for beachgoers and are of interest to coastal scientists. Several studies have been conducted to understand rip...     

Variability of zinc and manganese concentrations in relation to sex and season in the bivalve Donax trunculus

Females of Donax trunculus L. show higher concentrations of Mn and Zn than males. Differences are very high for Mn which also shows very large monthly fluctuations. Both the metals present higher contents during the period of gonadic maturation. Some high values of manganese found in the period when gonads are resting suggest the influence of sharp environmental variations in the area where bivalves have been collected.     

Equations of state for silicates in the metallic form

Summary We re-examine the problem of the mantle-core discontinuity. By means of theoretical equations of state for silicates in the metallic form, we conclude, once more, that it is a composition discontinuity rather than a phase transition.

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Sommario Si riesamina il problema della discontinuità tra il mantello ed il nucleo. Per mezzo di equazioni di stato teoriche si conclude che essa non può essere una transizione di fase.