The web of three-planet resonances in the outer Solar System     

Massimiliano Guzzo 《Icarus》2005,174(1):273-284

In this paper we numerically detect the web of three-planet resonances (i.e., resonances among mean anomalies, nodes and perihelia of three planets) with respect to the variation of the semi-major axis of Saturn and Jupiter, in a model including the planets from Jupiter to Neptune. The measure confirms the relevance of these resonances in the long-term evolution of the outer Solar System and provides a technique to identify some of the related coefficients.  相似文献   

Vector attenuation: elliptical polarization, raypaths and the Rayleigh-window effect     

José M. Carcione 《Geophysical Prospecting》2006,54(4):399-407

Waves in dissipative media exhibit elliptical polarization. The direction of the major axis of the ellipse deviates from the propagation direction. In addition, Snell's law does not give the raypath, since the propagation (wavevector) direction does not coincide with the energy‐flux direction. Each of these physical characteristics depends on the properties of the medium and on the inhomogeneity angle of the wave. The calculations are relevant for multicomponent surveys, where the receivers are placed on the ocean‐floor. An example of the role played by inhomogeneous waves is given by the Rayleigh‐window effect, which implies a significant amplitude reduction of the reflection coefficient of the ocean‐bottom.  相似文献   

Time-domain Modeling of Constant-Q Seismic Waves Using Fractional Derivatives   总被引：1，自引：0，他引：1  

J. M. Carcione  F. Cavallini  F. Mainardi  A. Hanyga 《Pure and Applied Geophysics》2002,159(7-8):1719-1736

— Kjartansson's constant-Q model is solved in the time-domain using a new modeling algorithm based on fractional derivatives. Instead of time derivatives of order 2, Kjartansson's model requires derivatives of order 2γ, with 0 <γ< 1/2, in the dilatation-stress formulation. The derivatives are computed with the Grünwald-Letnikov and central-difference approximations, which are finite-difference extensions of the standard finite-difference operators for derivatives of integer order. The modeling uses the Fourier method to compute the spatial derivatives, and therefore can handle complex geometries. A synthetic cross-well seismic experiment illustrates the capabilities of this novel modeling algorithm.  相似文献   

A parametric analytical model for non‐linear dynamics in cable‐stayed beam     

Vincenzo Gattulli  Massimiliano Morandini  Achille Paolone 《地震工程与结构动力学》2002,31(6):1281-1300

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Rayleigh waves in isotropic viscoelastic media   总被引：1，自引：0，他引：1  

José M. Carcione 《Geophysical Journal International》1992,108(2):453-464

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On the uniformity of anthropogenic Venice uplift     

Giuseppe Gambolati  Pietro Teatini  Massimiliano Ferronato  Tazio Strozzi  Luigi Tosi  Mario Putti 《地学学报》2009,21(6):467-473

A programme of Venice uplift because of seawater injection into a 600–800 m deep brackish aquifer underlying the lagoon has recently been advanced. As the actual spatial variability of the hydro‐geological parameters is to a large extent unknown, a controversial issue concerns the 25–30 cm heave prediction with the possible generation of differential displacements that might jeopardize the integrity of the architectural patrimony. It is shown that significant differential displacements have occurred in Venice in the past and are still presently occurring as evidenced by SAR interferometry. The results of a stochastic analysis addressing the variability of the hydraulic conductivity of the injected formation indicate that even a highly uneven aquifer expansion does not migrate to ground surface because of the smoothing effect exerted by the overburden. The predicted differential displacements are well below the values Venice is experiencing. Any a priori alarmism appears to be unfounded and unjustified.  相似文献   

The Late Pleistocene clastic deposits in the Romito Cave,southern Italy: a proxy record of environmental changes and human presence     

Massimiliano Ghinassi  Andrè C. Colonese  Zelia Di Giuseppe  Lisa Govoni  Domenico Lo Vetro  Giulia Malavasi  Fabio Martini  Silvia Ricciardi  Benedetto Sala 《第四纪科学杂志》2009,24(4):383-398

Clastic sediments deposited in caves and rock shelters bear peculiar sedimentological characteristics and have seldom been considered as a high‐resolution proxy record of climatic or environmental changes. The Romito Cave has its entrance at 275 m above sea level, about 25 km from the Tyrrhenian coast of Calabria, southern Italy. New archaeological excavation performed since 2000 has revealed a sedimentary succession spanning the record of Gravettian to Late Epigravettian cultures (Late Pleistocene). The present study focuses on the lower part (2.5 m thick) of the succession, where three main unconformity‐bounded stratigraphic units have been recognised (labelled RM1–3). Each unit consists of water‐lain deposits indicating high‐ to low‐competence flow, capped with anthropogenic deposits. The gradual deactivation and reactivation of the water drainage between 23 475 ± 190 and 16 250 ± 500 cal. a BP is correlated with regional precipitation changes due to the onset of dry climatic conditions of the Last Glacial Maximum. However, the deactivation of cave drainage after the deposition of unit RM3, around 15 400 ± 500 cal. a BP, deviates from the regional hydrological trend of progressively increasing water discharges and is attributed to the drainage cut‐off by probable cave wall collapses. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Synthetic logs of multipole sources in boreholes based on the Kelvin–Voigt stress–strain relation     

José M. Carcione  Flavio Poletto 《Geophysical Journal International》2008,174(3):808-814

We design a numerical algorithm for wave simulation in a borehole due to multipole sources. The stress–strain relation of the formation is based on the Kelvin–Voigt mechanical model to describe the attenuation. The modelling, which requires two anelastic parameters and twice the spatial derivatives of the lossless case, simulates 3-D waves in an axisymmetric medium by using the Fourier and Chebyshev methods to compute the spatial derivatives along the vertical and horizontal directions, respectively. Instabilities of the Chebyshev differential operator due to the implementation of the fluid–solid boundary conditions are solved with a characteristic approach, where the characteristic variables are evaluated at the source central frequency. The algorithm uses two meshes to model the fluid and the solid. The presence of the logging tool is modelled by imposing rigid boundary conditions at the inner surface of the fluid mesh. Examples illustrating the propagation of waves are presented, namely, by using monopoles, dipoles and a quadrupoles as sources in hard and soft formations. Moreover, the presence of casing and layers is considered. The modelling correctly simulates the features—traveltime and attenuation—of the wave modes observed in sonic logs, namely, the P and S body waves, the Stoneley wave, and the dispersive S waves in the case of multipole sources.  相似文献   

The Messina-Reggio earthquake of December 28, 1908     

J. M. Carcione  J. T. Kozák 《Studia Geophysica et Geodaetica》2008,52(4):661-672

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Construction dynamics of a lava channel     

Andrew J. L. Harris  Massimiliano Favalli  Francesco Mazzarini  Christopher W. Hamilton 《Bulletin of Volcanology》2009,71(4):459-474

We use a kinematic GPS and laser range finder survey of a 200 m-long section of the Muliwai a Pele lava channel (Mauna Ulu, Kilauea) to examine the construction processes and flow dynamics responsible for the channel–levee structure. The levees comprise three packages. The basal package comprises an 80–150 m wide ′a′a flow in which a ∼2 m deep and ∼11 m wide channel became centred. This is capped by a second package of thin (<45 cm thick) sheets of pahoehoe extending no more than 50 m from the channel. The upper-most package comprises localised ′a′a overflows. The channel itself contains two blockages located 130 m apart and composed of levee chunks veneered with overflow lava. The channel was emplaced over 50 h, spanning 30 May–2 June, 1974, with the flow front arriving at our section (4.4 km from the vent) 8 h after the eruption began. The basal ′a′a flow thickness yields effusion rates of 35 m³ s⁻¹ for the opening phase, with the initial flow advancing across the mapped section at ∼10 m/min. Short-lived overflows of fluid pahoehoe then built the levee cap, increasing the apparent channel depth to 4.8 m. There were at least six pulses at 90–420 m³ s⁻¹, causing overflow of limited extent lasting no more than 5 min. Brim-full flow conditions were thus extremely short-lived. During a dominant period of below-bank flow, flow depth was ∼2 m with an effusion rate of ∼35 m³ s⁻¹, consistent with the mean output rate (obtained from the total flow bulk volume) of 23–54 m³ s⁻¹. During pulses, levee chunks were plucked and floated down channel to form blockages. In a final low effusion rate phase, lava ponded behind the lower blockage to form a syn-channel pond that fed ′a′a overflow. After the end of the eruption the roofed-over pond continued to drain through the lower blockage, causing the roof to founder. Drainage emplaced inflated flows on the channel floor below the lower blockage for a further ∼10 h. The complex processes involved in levee–channel construction of this short-lived case show that care must be taken when using channel dimensions to infer flow dynamics. In our case, the full channel depth is not exposed. Instead the channel floor morphology reflects late stage pond filling and drainage rather than true channel-contained flow. Components of the compound levee relate to different flow regimes operating at different times during the eruption and associated with different effusion rates, flow dynamics and time scales. For example, although high effusion rate, brim-full flow was maintained for a small fraction of the channel lifetime, it emplaced a pile of pahoehoe overflow units that account for 60% of the total levee height. We show how time-varying volume flux is an important parameter in controlling channel construction dynamics. Because the complex history of lava delivery to a channel system is recorded by the final channel morphology, time-varying flow dynamics can be determined from the channel morphology. Developing methods for quantifying detailed flux histories for effusive events from the evidence in outcrop is therefore highly valuable. We here achieve this by using high-resolution spatial data for a channel system at Kilauea. This study not only indicates those physical and dynamic characteristics that are typical for basaltic lava flows on Hawaiian volcanoes, but also a methodology that can be widely applied to effusive basaltic eruptions.  相似文献