Sub-volcanic infiltration and syn-eruptive quenching of liquids in cumulate wall-rocks: the example of the gabbroic nodules of Stromboli (Aeolian Islands, Italy)     

M. Mattioli  G. Serri  E. Salvioli-Mariani  A. Renzulli  P. M. Holm  P. Santi  G. Venturelli 《Mineralogy and Petrology》2003,78(3-4):201-230

Summary ¶Fine- to coarse-grained plutonic nodules within the Petrazza pyroclastics (Paleo-Stromboli I period) consist of gabbroic rocks with variable amounts of interstitial material. They are characterised by cumulate textures and low pressure modal mineralogy formed by plagioclase (An_96–87)+clinopyroxene (Mg-v 82–94)+olivine (Fo_83–74)±amphibole±opaque minerals; the interstitial material consists of newly crystallised microlites (quenching) of plagioclase (An_73–55)+amphibole+clinopyroxene±olivine±biotite±opaques and highly variable amounts of residual glasses that range in composition from shoshonite and high-K basaltic andesite to high-K andesite and latite. The interstitial material has a relatively high but variable degree of vesicularity. The whole rock incompatible element abundances are lower than – but the patterns are typical of – in subduction related magmas and the incompatible trace-elements are well correlated with the amount of the interstitial material. The Sr, Pb and Nd isotopic ratios resemble those of the extrusive rocks of Stromboli older series and the mineral chemistry of the gabbros is similar to that of the HKCA Paleo-Stromboli lavas. Modal mineralogy, mineral chemistry and chemical-isotopic whole rock compositions suggest that the cumulus portions of the gabbroic nodules crystallised from basaltic magmas compositionally compatible with those erupted by Stromboli volcano. The interstitial material does not represent the residual liquid after in situ crystallisation of the gabbros; it is also distinct from the juvenile host andesite magma. Textural evidence, Fe–Mg mineral/liquid partioning and mass balance calculations indicate that the interstitial material (quench crystals and vesicular glass) derived from infiltrated hydrous basaltic liquid undercooling and vesiculation of which occurred during the eruption of the Petrazza pyroclastics.Received April 17, 2002; revised version accepted November 14, 2002 Published online June 2, 2003  相似文献   

A new analysis of the red giant branch 'tip' distance scale and the value of the Hubble constant   总被引：1，自引：0，他引：1  

Maurizio Salaris  & Santi Cassisi 《Monthly notices of the Royal Astronomical Society》1998,298(1):166-178

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The contribution of multitemporal SAR data in assessing hydrological parameters     

Paloscia  S. Macelloni  G. Pampaloni  P. Santi  E. 《Geoscience and Remote Sensing Letters, IEEE》2004,1(3):201-205

The sensitivity of radar backscattering to the principal hydrological parameters, such as vegetation biomass, soil moisture, and surface roughness, is discussed. Results obtained by using multifrequency synthetic aperture radar (SAR) data measured by the Jet Propulsion Laboratory Airborne Synthetic Aperture Radar, Spaceborne Imaging Radar-C, and European Remote Sensing 1/2 sensors are summarized. The sensitivity of L- and C-bands to spatial variations of plant and soil parameters is masked by the presence of surface roughness, which in turn affects the radar signal. However, from the observation of data collected at different dates and averaged over a relatively wide area that includes several fields, the correlation to soil moisture and vegetation biomass is found to be significant, since the effects of spatial variations are smoothed. On the other hand, the sensitivity to surface roughness becomes appreciable when multitemporal data are averaged in time, thus reducing the effects of temporal moisture variations.  相似文献   

Manifestazioni esalativo-idrotermali dell’ Isola d’ Ischia     

B. Santi 《Bulletin of Volcanology》1955,16(1):181-223

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Sources of debris flow material in burned areas   总被引：6，自引：2，他引：4  

Paul M. Santi  Victor G. deWolfe  Jerry D. Higgins  Susan H. Cannon  Joseph E. Gartner 《Geomorphology》2008,96(3-4):310

The vulnerability of recently burned areas to debris flows has been well established. Likewise, it has been shown that many, if not most, post-fire debris flows are initiated by runoff and erosion and grow in size through erosion and scour by the moving debris flow, as opposed to landslide-initiated flows with little growth. To better understand the development and character of these flows, a study has been completed encompassing 46 debris flows in California, Utah, and Colorado, in nine different recently burned areas. For each debris flow, progressive debris production was measured at intervals along the length of the channel, and from these measurements graphs were developed showing cumulative volume of debris as a function of channel length. All 46 debris flows showed significant bulking by scour and erosion, with average yield rates for each channel ranging from 0.3 to 9.9 m³ of debris produced for every meter of channel length, with an overall average value of 2.5 m³/m. Significant increases in yield rate partway down the channel were identified in 87% of the channels, with an average of a three-fold increase in yield rate. Yield rates for short reaches of channels (up to several hundred meters) ranged as high as 22.3 m³/m. Debris was contributed from side channels into the main channels for 54% of the flows, with an average of 23% of the total debris coming from those side channels. Rill erosion was identified for 30% of the flows, with rills contributing between 0.1 and 10.5% of the total debris, with an average of 3%. Debris was deposited as levees in 87% of the flows, with most of the deposition occurring in the lower part of the basin. A median value of 10% of the total debris flow was deposited as levees for these cases, with a range from near zero to nearly 100%. These results show that channel erosion and scour are the dominant sources of debris in burned areas, with yield rates increasing significantly partway down the channel. Side channels are much more important sources of debris than rills. Levees are very common, but the size and effect on the amount of debris that reaches a canyon mouth is highly variable.  相似文献   

The distance to Galactic globular clusters through RR Lyrae pulsational properties     

S. Cassisi  R. De Santis  A.M. Piersimoni 《Monthly notices of the Royal Astronomical Society》2001,326(1):342-348

By adopting the same approach outlined by De Santis & Cassisi, we evaluate the absolute bolometric magnitude of the zero-age horizontal branch (ZAHB) at the level of the RR Lyrae variable instability strip in selected Galactic globular clusters. This allows us to estimate the ZAHB absolute visual magnitude for these clusters and to investigate its dependence on the cluster metallicity. The derived M _V (ZAHB)–[Fe/H] relation, corrected in order to account for the luminosity difference between the ZAHB and the mean RR Lyrae magnitude, has been compared with some of the most recent empirical determinations in this field, such as the one provided by Baade–Wesselink analyses, RR Lyrae periods, Hipparcos data for field variables and main-sequence fitting based on Hipparcos parallaxes for field subdwarfs. As a result, our relation provides a clear support to the 'long' distance scale. We discuss also another method for measuring the distance to Galactic globular clusters. This method is quite similar to the one adopted for estimating the absolute bolometric magnitude of the ZAHB but it relies only on the pulsational properties of the Lyrae variables in each cluster. The reliability and accuracy of this method have been tested by applying it to a sample of globular clusters for which, owing to the morphology of their horizontal branch (HB), the use of the commonly adopted ZAHB fitting is a risky procedure. We notice that the two approaches for deriving the cluster distance modulus provide consistent results when applied to globular clusters, the RR Lyrae instability strip is well populated. As the adopted method relies on theoretical predictions on both the fundamental pulsational equation and the allowed mass range for fundamental pulsators, we give an estimate of the error affecting present results, owing to systematic uncertainties in the adopted theoretical framework.  相似文献   

Global metallicity of globular cluster stars from colour–magnitude diagrams     

F. Caputo  S. Cassisi 《Monthly notices of the Royal Astronomical Society》2002,333(4):825-834

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Scoring system to predict landslide runout in the Pacific Northwest,USA     

Wallace  Cory S.  Santi  Paul M.  Walton  Gabriel 《Landslides》2022,19(6):1449-1461

Landslides - Long-runout landslides can be extremely hazardous and unpredictable. The prediction of long-runout landslides is challenging because it is unclear what factors control their mobility,...  相似文献   

Temporal and spatial distributions of precursory seismicity rate changes in the Thailand-Laos-Myanmar border region: implication for upcoming hazardous earthquakes     

Prayot Puangjaktha  Santi Pailoplee 《Journal of Seismology》2018,22(1):303-313

To study the prospective areas of upcoming strong-to-major earthquakes, i.e., M _w  ≥ 6.0, a catalog of seismicity in the vicinity of the Thailand-Laos-Myanmar border region was generated and then investigated statistically. Based on the successful investigations of previous works, the seismicity rate change (Z value) technique was applied in this study. According to the completeness earthquake dataset, eight available case studies of strong-to-major earthquakes were investigated retrospectively. After iterative tests of the characteristic parameters concerning the number of earthquakes (N) and time window (T _w ), the values of 50 and 1.2 years, respectively, were found to reveal an anomalous high Z-value peak (seismic quiescence) prior to the occurrence of six out of the eight major earthquake events studied. In addition, the location of the Z-value anomalies conformed fairly well to the epicenters of those earthquakes. Based on the investigation of correlation coefficient and the stochastic test of the Z values, the parameters used here (N = 50 events and T _w  = 1.2 years) were suitable to determine the precursory Z value and not random phenomena. The Z values of this study and the frequency-magnitude distribution b values of a previous work both highlighted the same prospective areas that might generate an upcoming major earthquake: (i) some areas in the northern part of Laos and (ii) the eastern part of Myanmar.  相似文献   

Galactic globular clusters as a test for very-low-mass stellar models     

S. Cassisi  V. Castellani  P. Ciarcelluti  G. Piotto  M. Zoccali 《Monthly notices of the Royal Astronomical Society》2000,315(4):679-688

We make use of the 'Next Generation' model atmospheres of Allard et al. and Hauschildt, Allard & Baron to compute theoretical models for low- and very-low-mass stars for selected metallicities in the range Z =0.0002 to 0.002. On this basis, we present theoretical predictions covering the sequence of H-burning stars as observed in Galactic globulars from the faint end of the main sequence up to, and beyond, the cluster turn-off. The role played by the new model atmospheres is discussed, showing that present models appear in excellent agreement with models by Baraffe et al. as computed on a quite similar physical basis. One finds that the theoretical mass–luminosity relations based on this updated set of models are in good agreement with the empirical data provided by Henry & McCarthy. Comparison with HST observation discloses that the location on the colour–magnitude diagram of the lower main sequence in Galactic globular clusters appears again in good agreement with the predicted sensitive dependence of these sequences on the cluster metallicity.  相似文献