A fast algorithm for 3D azimuthally anisotropic velocity scan          下载免费PDF全文

Sergey Fomel  Lexing Ying 《Geophysical Prospecting》2015,63(2):368-377

The conventional velocity scan can be computationally expensive for large‐scale seismic data sets, particularly when the presence of anisotropy requires multiparameter scanning. We introduce a fast algorithm for 3D azimuthally anisotropic velocity scan by generalizing the previously proposed 2D butterfly algorithm for hyperbolic Radon transforms. To compute semblance in a two‐parameter residual moveout domain, the numerical complexity of our algorithm is roughly as opposed to of the straightforward velocity scan, with N being the representative of the number of points in a particular dimension of either data space or parameter space. Synthetic and field data examples demonstrate the superior efficiency of the proposed algorithm.  相似文献   

Short-Term Surface Deformation on the Northern Hayward Fault,CA, and Nearby Landslides Using Polarimetric SAR Interferometry (PolInSAR)     

Samira Alipour  Kristy F. Tiampo  Sergey V. Samsonov  Pablo J. González 《Pure and Applied Geophysics》2015,172(8):2179-2193

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Shifted hyperbola moveout approximation revisited     

Alexey Stovas  Sergey Fomel 《Geophysical Prospecting》2012,60(3):395-399

The shifted hyperbola approximation is widely used in seismic applications. Mostly, this approximation is applied to reflection moveout in multilayered media. The traditional domain for this application is the t ‐ x domain. In this paper, we discuss the use of this approximation in the τ ‐ p and t ‐ p domains. The accuracy of the shifted hyperbola approximation defined in different domains is illustrated by analytical and numerical examples.  相似文献   

Catastrophic detachment and high-velocity long-runout flow of Kolka Glacier, Caucasus Mountains, Russia in 2002   总被引：1，自引：0，他引：1  

Stephen G. Evans  Olga V. Tutubalina  Valery N. Drobyshev  Sergey S. Chernomorets  Scott McDougall  Dmitry A. Petrakov  Oldrich Hungr 《Geomorphology》2009,105(3-4):314-321

In September 2002, a catastrophic geomorphic event occurred in the Caucasus Mountains, southern Russia, in which almost the entire mass of Kolka Glacier detached from its bed, accelerated to a very high velocity (max. 65–80 m/s), and traveled a total distance of 19 km downstream as a glacier-debris flow. Based on the interpretation of satellite imagery obtained only 8.5 h before the event occurred, the analysis of seismograms from nearby seismic stations, and subsequent detailed field observations and measurements, we suggest that this remarkable event was not a response to impulse loading from a rock avalanche in the mountainside above the glacier, or to glacier surging, but due entirely to the static and delayed catastrophic response of the Kolka glacier to ice and debris loading over a period of months prior to the September 20 detachment. We reconstruct the glacier-debris flow using field observations in conjunction with the interpretation of seismographs from nearby seismic stations and successfully simulate the behaviour (runout, velocity, and deposition) of the post-detachment glacier-debris flow using a three-dimensional analytical model. Our demonstration of a standing-start hypothesis in the 2002 Kolka Glacier detachment has substantial implications for glacier hazard assessment and risk management strategies in valleys downstream from unstable debris-covered glaciers in the mountain regions of the world.  相似文献   

Acoustic Emissions Monitoring during Inelastic Deformation of Porous Sandstone: Comparison of Three Modes of Deformation   总被引：4，自引：0，他引：4  

Jerome Fortin  Sergei Stanchits  Georg Dresen  Yves Gueguen 《Pure and Applied Geophysics》2009,166(5-7):823-841

In some reservoirs, large deformations can occur during oil or gas production because of the effective stress change. For very porous rocks, these production operations can be sufficient to cause inelastic deformation and irreversible damage. Rock formations can undergo deformation by different mechanisms, including dilatancy or pore collapse. In the laboratory, it has been shown that the inelastic deformation and failure mode of porous rocks are pressure sensitive. Indeed, when subjected to an overall compressive loading, a porous rock may fail by shear localization, compaction localization, or by cataclastic compaction. Acoustic emission (AE) records provide important information to understand the failure mode of rocks: the spatial evolution of damage as well as the source mechanisms can be followed using this technique. In this paper, we present three different laboratory axisymmetric compression experiments, performed on Bleurswiller sandstone, which enable us to compare the acoustic emission signature of these three modes of deformation. Our data show that compaction localization and cataclastic compaction are characterized by similar acoustic signatures (in terms of AE sources characteristics and evolution of AE number), in comparison to the acoustic signature from shear localization. This implies similar micromechanisms involved during compaction bands formation and cataclastic compaction.  相似文献   

Intercomparison between finite element and finite volume approaches to model North Sea tides     

Silvia Maßmann  Alexey Androsov  Sergey Danilov 《Continental Shelf Research》2010

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Galactic cosmic rays—clouds effect and bifurcation model of the Earth global climate. Part 2. Comparison of theory with experiment     

Vitaliy D. Rusov  Vladimir N. Vaschenko  Elena P. Linnik  Оksana T. Myhalus  Yuriy A. Bondartchuk  Vladimir P. Smolyar  Sergey I. Kosenko  Strachimir Cht. Mavrodiev  Boyko I. Vachev 《Journal of Atmospheric and Solar》2010,72(5-6):389-397

The solution of energy-balance model of the Earth global climate and the EPICA Dome C and Vostok experimental data of the Earth surface palaeotemperature evolution over past 420 and 740 kyr are compared.In the framework of proposed bifurcation model (i) the possible sharp warmings of the Dansgaard-Oeschger type during the last glacial period due to stochastic resonance is theoretically argued; (ii) the concept of climatic sensitivity of water in the atmosphere, whose temperature instability has the form of so-called hysteresis loop, is proposed, and based on this concept the time series of global ice volume over the past 1000 kyr, which is in good agreement with the time series of δ¹⁸O concentration in the sea sediments, is obtained; (iii) the so-called “CO₂ doubling” problem is discussed.  相似文献   

On utility of triangular C-grid type discretization for numerical modeling of large-scale ocean flows   总被引：1，自引：0，他引：1  

Sergey Danilov 《Ocean Dynamics》2010,60(6):1361-1369

Ocean circulation models based on triangular C-grid discretization are frequently employed to simulate coastal ocean dynamics on unstructured meshes. It is shown that on time and space scales dominated by slow geostrophic dynamics, this discretization tends to exhibit checkerboard noise in the field of horizontal velocity divergence and vertical velocity, respectively. The noise is linked to the geometry of triangular C-grid and is amplified in regimes that are close to geostrophic balance through the particular structure of the Coriolis operator. It can be partly suppressed in some cases but remains a problem in a general case and makes the triangular C-grid a suboptimal choice for large-scale ocean modeling.  相似文献   

Alteration and chemical U-Th-total Pb dating of heterogeneous high-uranium zircon from a pegmatite from the Aduiskii massif,middle Urals,Russia     

Zamyatin  Dmitry A.  Shchapova  Yuliya V.  Votyakov  Sergey L.  Nasdala  Lutz  Lenz  Christoph 《Mineralogy and Petrology》2017,111(4):475-497

Mineralogy and Petrology - The U-Th-Pb isotope system in the accessory mineral zircon may be disturbed, as for instance by the secondary loss of radiogenic lead. The recognition of such alteration...  相似文献   

Geomorphological evidence for the Late Holocene evolution and the Holocene lake level maximum of the Aral Sea   总被引：1，自引：0，他引：1  

Christian Reinhardt  Bernd Wünnemann  Sergey K. Krivonogov   《Geomorphology》2008,93(3-4):302-315

During the Holocene the Aral Sea underwent various transgressive and regressive phases of different magnitudes. However, previous work has not yet fully clarified the evolution and chronology of the individual phases. Research presented here throws light on the evolution of the Aral Sea during the past  2000 years. It includes field surveys, tachymetric and DGPS-derived altitude measurements, analysis of sediments from two areas of the northern and southern Aral Basin (Tastubek Bay and Karaumbet Bay), and their correlation with GIS-based lake area models. Geomorphological and sedimentological evidence from the study areas shows a transgression of the Aral Sea around 200 AD, ending at a lake level maximum of 54 to 55 m. After a medieval regression, the lake reached this level again between the late 16th and early 19th century AD. The digital elevation model SRTM-3 was used to estimate a lake size of 72,400 km² for the lake level maximum.Elevated palaeoshorelines, specifically at 72–73 m, are completely absent in the study areas. Local remains of escarpments at elevations of 66 m and 73 m are due to resistant Miocene caprock and are therefore not interpretable as shoreline features.  相似文献