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GPU-acceleration 3D rotated-staggered-grid solutions to microseismic anisotropic wave equation with moment tensor implementation

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International Journal of Mining Science and Technology 2023年第4期33卷 403-410页

作者： Jing Zheng Lingbin Meng Yuan Sun Suping Peng State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology-BeijingBeijing 100083China College of Geoscience and Surveying Engineering China University of Mining and Technology-BeijingBeijing 100083China

To improve the accuracy of microseismic inversion,seismic anisotropy and moment tensor source should be carefully considered in the forward modelling *** this study,3D microseismic anisotropy wave forward modelling with a moment tensor source was *** modelling was carried out based on a rotated-staggered-grid(RSG)*** contrast to staggered-grids,the RSG scheme defines the velocity components and densities at the same grid,as do the stress components and elastic ***,the elastic moduli do not need to be *** addition,the detailed formulation and implementation of moment-tensor source loaded on the RSG was presented by equating the source to the stress ***,the RSG-based 3D wave equation forward modelling was performed in parallel using compute unified device architecture(CUDA)programming on a graphics processing unit(GPU)to improve its *** simulations including homogeneous and anisotropic models were carried out using the method proposed in this paper,and compared with other methods to prove the reliability of this ***,the high efficiency of the proposed approach was *** results show that the computational efficiency of proposed method can be improved by about two orders of magnitude compared with traditional central processing unit(CPU)computing *** could not only help the analysis of microseismic full wavefield records,but also provide support for passive source inversion,including location and focal mechanism inversion,and velocities inversion.

关键词： Microseismic Forward modelling seismic anisotropy Moment tensor

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Modeling the efects of fracture infll on frequency‑dependent anisotropy and AVO response of a fractured porous layer

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Petroleum Science 2021年第3期18卷 758-772页

作者： Yan-Xiao He Xin-Long Li Gen-Yang Tang Chun-Hui Dong Mo Chen Shang-Xu Wang State Key Laboratory of Petroleum Resources and Prospecting CNPC Key Laboratory of Geophysical ExplorationChina University of Petroleum(Beijing)Beijing 102249China Daqing Oilfeld Exploration and Development Institute Daqing 163000Heilongjiang ProvinceChina

In a fractured porous hydrocarbon reservoir,wave velocities and refections depend on frequency and incident angle.A proper description of the frequency dependence of amplitude variations with ofset(AVO)signatures should allow efects of fracture inflls and attenuation and dispersion of fractured *** novelty of this study lies in the introduction of an improved approach for the investigation of incident-angle and frequency variations-associated refection *** improved AVO modeling method,using a frequency-domain propagator matrix method,is feasible to accurately consider velocity dispersion predicted from frequency-dependent elasticities from a rock physics *** hence,the method is suitable for use in the case of an anisotropic medium with aligned ***,the proposed modeling approach allows the combined contributions of layer thickness,interbedded structure,impedance contrast and interferences to frequency-dependent refection coefcients and,hence,yielding seismograms of a layered model with a dispersive and attenuative *** numerical results show bulk modulus of fracture fuid signifcantly afects anisotropic attenuation,hence causing frequencydependent refection *** implications indicate the study of amplitude versus angle and frequency(AVAF)variations provides insights for better interpretation of refection anomalies and hydrocarbon identifcation in a layered reservoir with vertical transverse isotropy(VTI)dispersive media.

关键词： seismic anisotropy Fractured media Attenuation and dispersion AVO responses Frequency dependence

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Anomalous elasticity of talc at high pressures:Implications for subduction systems

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Geoscience Frontiers 2022年第4期13卷 34-47页

作者： Ye Peng Mainak Mookherjee Andreas Hermann Geeth Manthilake David Mainprice Earth Materials Laboratory Department of EarthOceanand Atmospheric SciencesFlorida State UniversityTallahasseeFL 32306USA Centre for Science at Extreme Conditions and SUPA School of Physics and AstronomyThe University of EdinburghEdinburgh EH93FDUK Laboratoire Magmas et Volcans CNRS IRDOPGCUniversitéClermont Auvergne63000 Clermont-FerrandFrance Geosciences Montpellier UMR CNRS 5243Universitéde MontpellierMontpellier 34095France

Talc is a layered hydrous silicate mineral that plays a vital role in transporting water into Earth’s interior and is crucial for explaining geophysical observations in subduction zone *** this study,we explored the structure,equation of state,and elasticity of both triclinic and monoclinic talc under high pressures up to 18 GPa using first principles simulations based on density functional theory corrected for dispersive *** results indicate that principal components of the full elastic constant tensor C_(11) and C_(22),shear components C_(66),and several off-diagonal components show anomalous pressure *** non-monotonic pressure dependence of elastic constant components is likely related to the structural changes and is often manifested in a polytypic transition from a low-pressure polytype talc-I to a high-pressure polytype talc-Ⅱ.The polytypic transition of talc occurs at pressures within its thermodynamic ***,the bulk and shear elastic moduli show no anomalous *** study also shows that talc has low velocity,extremely high anisotropy,and anomalously high V_(P)/V_(S) ratio,thus making it a potential candidate mineral phase that could readily explain unusually high V_(P)/V_(S) ratio and large shear wave splitting delays as observed from seismological studies in many subduction systems.

关键词： Talc Elasticity seismic anisotropy Hydrous minerals Subduction zone

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A Synthesis of Geophysical Data in Southeastern North China Craton:Implications for the Formation of the Arcuate Xuhuai Thrust Belt

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Journal of Earth Science 2022年第3期33卷 552-566页

作者： Yangfan Deng Yun Chen Pengfei Li Zhou Zhang JoséBadal State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China CAS Center for Excellence in Deep Earth Science Guangzhou 510640China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Physics of the Earth Sciences BUniversity of ZaragozaPedro Cerbuna 1250009 ZaragozaSpain

The Xuhuai fold thrust belt(XHTB)is a curved structure in the southeastern margin of the North China Craton(NCC)that has attracted great attentions due to its tectonic and petrological ***,few geophysical studies have focused on the deep structure of this *** this study,we carry out a systematic demonstration of the main geophysical features that characterize the XHTB and surrounding *** results reveal small negative gravity and magnetic anomalies,thin crust and lithosphere,lower shear velocity and shallower earthquake epicenters relative to other areas of the NCC,collectively indicating a lithospheric-scale rheological anomaly at this *** magnetic alignments show a trend similar to that of geological units in southeastern NCC and adjacent areas,although they differ from the SKS-splitting fast polarization directions,except in the Qinling-Dabie orogen where a vertical coherent deformation of the crust and mantle may be involved *** on the geophysical data,we propose a detachment-controlled model,which was caused by the different detachment depth/strength,for the formation of XHTB to explain its arcuate shape as well as the magnetic alignments,thus providing new insight into the deep processes of southeastern NCC.

关键词： gravity and magnetic anomalies shear wave velocity seismicity seismic anisotropy magnetic alignments arcuate structure

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A seismological evidence for the northwestward movement of Africa with respect to Iberia from shear-wave splitting

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Geoscience Frontiers 2012年第5期3卷 681-696页

作者： Mohamed K.Salah Geology Department Faculty of Science Tanta UniversityTanta 31527Egypt

seismic anisotropy and its main features along the convergent boundary between Africa and Iberia are detected through the analysis of teleseismic shear-wave splitting. Waveform data generated by 95 teleseismic events recorded at 17 broadband stations deployed in the western Mediterranean region are used in the present study. Although the station coverage is not uniform in the Iberian Peninsula and north- west Africa, significant variations in the fast polarization directions and delay times are observed at stations located at different tectonic domains. Fast polarization directions are oriented predominantly NW-SE at most stations which are close to the plate boundary and in central Iberia; being consistent with the absolute plate motion in the region. In the northern part of the Iberian Peninsula, fast velocity direc- tions are oriented nearly E--W; coincident with previous results. Few stations located slightly north of the plate boundary and to the southeast of lberia show E--W to NE-SW fast velocity directions, which may be related to the Alpine Orogeny and the extension direction in lberia. Delay times vary significantly between 0.2 and 1.9 s for individual measurements, reflecting a highly anisotropic structure beneath the recording stations. The relative motion between Africa and lberia represents the main reason for the observed NW-SE orientations of the fast velocity directions. However, different causes of anisotropy have also to be considered to explain the wide range of the splitting pattern observed in the western Mediterranean region. Many geophysical observations such as the low Pn velocity, lower lithospheric Q values, higher heat flow and the presence of high conductive features support the mantle flow in the western Mediterranean, which may contribute and even modify the splitting pattern beneath the studied region.

关键词： Shear-wave splitting seismic anisotropy Iberian Peninsula Northwest Africa Western Mediterranean

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V_p/V_s anisotropy and Implications for Crustal Composition Identification and Earthquake Prediction

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Acta Geologica Sinica(English Edition) 2009年第4期83卷 801-815页

作者： WANG Qian JI Shaocheng XU Zhiqin Departement des Genies Civil Geologique et des Mines Ecole Polytechnique de Montreal Montreal H3C 3A7 Canada Key Laboratory of Continental Dynamics Ministry of Land and Resources Chinese Academy of Geological Sciences 10037 Beijing China

The ratio of P- to S-wave velocities （Vp/Vs） is regarded as one of the most diagnostic properties of natural rocks. It has been used as a discriminant of composition for the continental crust and provides valuable constraints on its formation and evolution processes. Furthermore, the spatial and temporal changes in Vp/Vs before and after earthquakes are probably the most promising avenue to understanding the source mechanics and possibly predicting earthquakes. Here we calibrate the variations in Vp/Vs in dry, anisotropic crustal rocks and provide a set of basic information for the interpretation of future seismic data from the Wenchuan earthquake Fault zone Scientific Drilling （WFSD） project and other surveys. Vp/Vs is a constant （Ф0） for an isotropic rock. However, most of crustal rocks are anisotropic due to lattice-preferred orientations of anisotropic minerals （e.g., mica, amphibole, plagioclase and pyroxene） and cracks as well as thin compositional layering. The Vp/Vs ratio of an anisotropic rock measured along a selected pair of propagation-vibration directions is an apparent value （Фy） that is significantly different from the value for its isotropic counterpart （Ф0）. The usefulness of apparent Vp/Vs ratios as a diagnostic of crustal composition depends largely on rock seismic anisotropy. A 5% of P- and S-wave velocity anisotropy is sufficient to make it impossible to determine the crustal composition using the conventional criteria （Vp/Vs≤1.756 for felsic rocks, 1.756〈Vp/Vs≤1.809 for intermediate rocks, 1.809〈Vp/Vs≤1.944 for mafic rocks, and Vp/V2〉1.944 fluidfilled porous/fractured or partially molten rocks） if the information about the wave propagation-polarization directions with respect to the tectonic framework is unknown. However, the variations in Vp/Vs measured from borehole seismic experiments can be readily interpreted according to the orientations of the ray path and the polarization of the shear waves with respect to the present-day principal stre

关键词： Vp/Vs ratio seismic anisotropy Crustal composition Earthquake prediction

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Lattice-Preferred orientations of olivine in subducting oceanic lithosphere derived from the observed seismic anisotropies in double seismic zones

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Earthquake Science 2016年第4期29卷 243-258页

作者： Peng Han Dongping Wei Keliang Zhang Zhentian Sun Xiaoya Zhou Key Laboratory of Computational Geodynamics Chinese Academy of Sciences Beijing 100049 China College of Earth Science University of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing 100029China Beijing Geotherm Research Institute Beijing 100143 China

Subduction zones can generally be classified into Mariana type and Chilean type depending on plate ages, plate thicknesses, subduction angles, back-arc deformation patterns, etc. The double seismic zones （DSZs） in sub- duction zones are mainly divided into type I and type II which, respectively, correspond to the Mariana type and Chilean type in most cases. seismic anisotropy is an important parameter characterizing the geophysical fea- tures of the lithosphere, including the subduction zones, and can be described by the two parameters of delay time ~t and fast wave polarization direction ~b. We totally col- lected 524 seismic anisotropy data records from 24 DSZs and analyzed the statistical correlations between seismic anisotropy and the related physical parameters of DSZs. Our statistical analysis demonstrated that the fast wave polarization directions are parallel to the trench strike with no more than 30~ for most type I DSZs, while being nearlyperpendicular to the trench strike for type II DSZs. We also calculated roughly linear correlations that the delay time 6t increases with dip angles but decreases with subduction rates. A linear equation was summarized to describe the strong correlation between DSZ＇s subduction angle DSZ and seismic anisotropy in subduction zones. These results suggest that the anisotropic structure of the subducting lithosphere can be described as a possible equivalent crystal similar to the olivine crystal with three mutually orthogonal polarization axes, of which the longest and the second axes are nearly along the trench-perpendicular and trench-parallel directions, respectively.

关键词： seismic anisotropy Double seismic zonesSubduction zone processes Plate motions Microstructures

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Upper crustal deformation characteristics in the northeastern Tibetan Plateau and its adjacent areas revealed by GNSS and anisotropy data

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地震学报:英文版 2023年第4期36卷 297-308页

作者： Shuyu Li Yuan Gao Honglin Jin Key Laboratory of Earthquake Prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing 100036China

The northeastern part of the Tibetan Plateau is a region where different tectonic blocks collide and intersect,and large earthquakes are *** Navigation Satellite System(GNSS)observations show that tectonic deformation in this region is strong and manifests as non-uniform deformation associated with tectonic features.S-wave splitting studies of near-field seismic data show that seismic anisotropy parameters can also reveal the upper crustal medium deformation beneath the reporting *** this paper,we summarize the surface deformation from GNSS observations and crustal deformation from seismic anisotropy data in the northeastern Tibetan *** comparing the principal compressive strain direction with the fast S-wave polarization direction of near-field S-wave splitting,we analyzed deformation and its differences in surface and upper crustal media in the northeastern Tibetan Plateau and adjacent *** principal compressive strain direction derived from GNSS is generally consistent with the polarization direction of fast S-waves,but there are also local tectonic regions with large differences between them,which reflect the different deformation mechanisms of regional upper crustal *** combination of GNSS and seismic anisotropy data can reveal the depth variation characteristics of crustal deformation and deepen understanding of three-dimensional crustal deformation and the deep dynamical mechanisms underlying ***.

关键词： upper crustal deformation northeastern Tibetan Plateau GNSS seismic anisotropy deformation differences

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D″anisotropy inverted from shear wave splitting intensity

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Earthquake Science 2022年第2期35卷 93-104页

作者： Chao Zhang Zhouchuan Huang School of Earth Sciences and Engineering Nanjing UniversityNanjing 210023China

The D″layer,located at the bottom of the mantle,is an active thermochemical boundary *** upwelling of mantle plumes,as well as possible plate subduction in the D″layer,could lead to large-scale material transformation and mineral deformation,which could result in significant seismic ***,owing to limited observations and immense computational cost,the anisotropic structures and geodynamic mechanisms in the D″layer remain poorly *** this study,we proposed a new inversion method for the seismic anisotropy in the D″layer quantitatively with shear wave splitting *** first proved the linearity of the splitting intensities under the ray-theory *** synthetic tests showed that,with horizontal axes of symmetry and ray incidences lower than 30°in the D″layer(typical SKS phase),the anisotropy is well *** applied the method to the measured dataset in Africa and Western Europe,and obtained strong D″anisotropy in the margins of the large low shear-wave velocity provinces and subducting *** new method makes it possible to obtain D″anisotropy,which provides essential constraints on the geodynamical processes at the base of the mantle.

关键词： seismic anisotropy splitting intensity D″layer plume slab

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Shear-wave splitting in the crust:Regional compressive stress from polarizations of fast shear-waves

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Earthquake Science 2012年第1期25卷 35-45页

作者： Yuan Gao Yutao Shi Jing Wu Lingxue Tai Institute of Earthquake Science China Earthquake AdministrationBeijing 100036China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

When propagating through anisotropic rocks in the crust, shear-waves split into faster and slower components with almost orthogonal polarizations. For nearly vertical propagation the polarization of fast shear- wave （PFS） is parallel to both the strike of the cracks and the direction of maximum horizontal stress, therefore it is possible to use PFS to study stress in the crust. This study discusses several examples in which PFS is applied to deduce the compressive stress in North China, Longmenshan fault zone of east edge of Tibetan plateau and Yunnan zone of southeast edge of Tibetan plateau, also discusses temporal variations of PFS orientations of 1999 Xiuyan earthquake sequences of northeastern China. The results are consistent to those of other independent traditional stress measurements. There is a bridge between crustal PFS and the crustal principal compressive stress although there are many unclear disturbance sources. This study suggests the PFS results could be used to deduce regional and in situ principal compressive stress in the crust only if there are enough seismic stations and enough data. At least, PFS is a useful choice in the zone where there are a large number of dense seismic stations.

关键词： polarization of fast shear-wave shear-wave splitting compressive stress in the crust seismic anisotropy

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