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azimuthal anisotropy in Xe-Xe and Pb-Pb Collisions with the Monte Carlo Model HYDJET plus plus and the CMS Detector at the Energies of the LHC

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MOSCOW UNIVERSITY PHYSICS BULLETIN 2024年第SUPPL1期79卷 82-85页

作者： Myagkov, D. A. Petrushanko, S. V. Lomonosov Moscow State Univ Fac Phys Moscow 119991 Russia Lomonosov Moscow State Univ Skobeltsyn Inst Nucl Phys Moscow 119991 Russia

The article presents the results of modeling the heavy-ion collisions of xenon and lead systems in the Monte Carlo generator HYDJET++. The relations of the azimuthal distributions of charged particles in Xe-Xe and Pb-Pb collisions are given. The simulation results are compared with the CMS experiment. In addition, predictions are given for the azimuthal distributions of charged particles in relativistic collisions of oxygen nuclei.

关键词： ultrarelativistic heavy-ion collisions quark-gluon plasma azimuthal anisotropy correlations elliptic flow triangular flow jet quenching

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The P-wave velocity and azimuthal anisotropy structure of southeastern margin of the Tibetan Plateau from adjoint-state traveltime tomography

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Science China Earth Sciences 2025年第3期68卷 702-719页

作者： Xuezhen ZHANG Xiaodong SONG Jing CHEN Lei ZHANG Ping TONG Yan’e LI State Key Laboratory of Deep Earth and Mineral Exploration School of Earth and Space SciencesPeking UniversityBeijing 100871China Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore Institute of Geophysics China Earthquake AdministrationBeijing 100081China

The southeastern margin of the Tibetan Plateau is a crucial region to understand the mechanisms of plateau uplift and deformation. This region is seismically active and has experienced multiple large earthquakes, resulting in significant human and economic losses. Constructing velocity and anisotropic tomography models is crucial for understanding the seismogenic mechanism and deep structural deformation in this area. In this study, we extract high-quality P-wave first-arrival data from the earthquake catalog of the China Earthquake Administration and use them to construct both common-receiver and commonsource differential traveltime datasets. We then apply a novel adjoint-state traveltime tomography approach to obtain new Pwave velocity and azimuthal anisotropy models for the region. This method eliminates the need for ray tracing, thereby reducing the potential bias from the ray theory and ray tracing. A comparison between our results and previous imaging models and shearwave splitting measurements reveals several new details. The results indicate weak anisotropy in the shallow depth of the central Chuandian block. Two low-velocity anomalies are identified beneath the Songpan-Ganzi and Lijiang-Xiaojinhe fault zones, as well as beneath the Xiaojiang Fault. The distinct anisotropic characteristics of these two low-velocity anomalies suggest different tectonic contexts: Beneath the Songpan-Ganzi and Lijiang-Xiaojinhe fault zones, the azimuthal anisotropy aligns north-south and northeast-southwest, while beneath the Xiaojiang Fault, it aligns northwest-southeast. In addition, the anisotropy of the upper mantle in the southern part of the study area has a significant east-west feature. The earthquake relocation results reveal intensified seismic activity in regions with significant velocity contrasts and near fault zones. Segmental seismic activity is observed along some major fault zones, and seismicity is also more pronounced in fault intersection areas. The new imag

关键词： azimuthal anisotropy P-wave velocity Adjoint-state tomography Tibetan Plateau Sichuan and Yunnan

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Seismic azimuthal anisotropy of New Zealand revealed by adjoint-state traveltime tomography

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EARTH AND PLANETARY SCIENCE LETTERS 2025年 660卷

作者： Wu, Shucheng Chen, Jing Tong, Ping Nanyang Technol Univ Sch Phys & Math Sci Div Math Sci Singapore Singapore China Univ Geosci State Key Lab Geol Proc & Mineral Resources Wuhan Peoples R China Nanyang Technol Univ Earth Observ Singapore Singapore Singapore

The omission of seismic anisotropy in current reference models covering the entire New Zealand has been an obstacle to achieving a comprehensive understanding of deformation and dynamics along the complex Pacific-Australian plate boundary segment. Here we present a 3D azimuthally anisotropic model that encompasses both the North and South Islands of New Zealand to a depth of 40 km, using over 1 million local P-wave arrival times and a newly developed adjoint-state traveltime tomography technique. This model is built upon the New Zealand-wide 3D isotropic velocity model, serving as an essential and incremental update to the existing model. Our new model highlights significant variations in anisotropy across the plate boundary region, indicating distinct deformation states between tectonic blocks. In the North Island, pronounced along-strike changes in anisotropy are evident beneath the Hikurangi forearc, which could be attributed to variations in stress regime associated with the oblique plate convergence and changes in interseismic coupling of the subduction megathrust. The oblique plate motion further induces pure shear deformation in the middle to lower crust of the southern backarc, resulting in strong anisotropy with fast axes perpendicular to the principal axes of maximum horizontal compression. In contrast, seismic anisotropy in the central South Island primarily stems from the preferential alignment of minerals, notably within the Haast schist in the Otago block. However, anisotropy in the middle to lower crust of the northern South Island may represent inherited structures that originated during past southward subductions along the Gondwana margins at similar to 100 Ma. Our new model offers valuable insights into the intricate geological processes occurring within the plate boundary region.

关键词： Seismic tomography azimuthal anisotropy New Zealand plate boundary Subduction zone deformation Adjoint-state method

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Upper crustal azimuthal anisotropy and seismogenic tectonics of the Hefei segment of the Tan-Lu Fault Zone from ambient noise tomography

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Earth and Planetary Physics 2025年第2期9卷 253-265页

作者： Cheng Li HuaJianYao Song Luo HaiJiang Zhang LingLi Li XiaoLi Wang ShengJun Ni State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan Anhui 232001China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaBozhou Anhui 233500China Anhui Earthquake Agency Hefei 230031China Anhui Huizhou Geology Security Institute Company Ltd.Hefei 231202China

The Tan-Lu Fault Zone is a large NNE-trending fault zone that has a substantial effect on the development of eastern China and its earthquake disaster prevention efforts. Aiming at the azimuthally anisotropic structure in the upper crust and seismogenic tectonics in the Hefei segment of this fault, we collected phase velocity dispersion data of fundamental mode Rayleigh waves from ambient noise cross-correlation functions of ~400 temporal seismographs in an area of approximately 80 × 70 km along the fault zone. The period band of the dispersion data was ~0.5–10 s. We inverted for the upper crustal three-dimensional(3-D) shear velocity model with azimuthal anisotropy from the surface to 10 km depth by using a 3-D direct azimuthal anisotropy inversion method. The inversion result shows the spatial distribution characteristics of the tectonic units in the upper crust. Additionally, the deformation of the Tan-Lu Fault Zone and its conjugated fault systems could be inferred from the anisotropy model. In particular, the faults that have remained active from the early and middle Pleistocene control the anisotropic characteristics of the upper crustal structure in this area. The direction of fast axes near the fault zone area in the upper crust is consistent with the strike of the faults, whereas for the region far away from the fault zone, the direction of fast axes is consistent with the direction of the regional principal stress caused by plate movement. Combined with the azimuthal anisotropy models in the deep crust and uppermost mantle from the surface wave and Pn wave, the different anisotropic patterns caused by the Tan-Lu Fault Zone and its conjugated fault system nearby are shown in the upper and lower crust. Furthermore,by using the double-difference method, we relocated the Lujiang earthquake series, which contained 32 earthquakes with a depth shallower than 10 km. Both the Vs model and earthquake relocation results indicate that earthquakes mostly occurred in th

关键词： ambient noise tomography azimuthal anisotropy upper crust seismogenic structure the Tan-Lu Fault Zone Hefei segment

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3D shear wave velocity and azimuthal anisotropy structure in the shallow crust of Binchuan Basin in Yunnan, Southwest China, from ambient noise tomography

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Earthquake Research Advances 2024年第4期4卷 73-82页

作者： Jing Wang Huajian Yao Ying Liu Baoshan Wang Weitao Wang Laboratory of Seismology and Physics of the Earth's Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng233500China Institute of Geophysics China Earthquake AdministrationBeijing100081China

The Binchuan Basin in northwest Yunnan, southwest China, is a rift basin developed at the intersection of the Red River Fault and Chenghai Fault, where historical earthquakes have occurred. Understanding the fine velocity structure of the shallow crust in this region can help improve earthquake location accuracy and our understanding of the relationship between fault zone structures and fault slip behaviors. Using the continuous waveform data recorded by 381 dense array stations in 2017, we obtained 7 915 Rayleigh-wave phase velocity dispersion curves in the period band of 0.2–6 s from ambient noise cross-correlation functions after rigorous data processing and quality control. We determined 3D isotropic and azimuthally anisotropic shear wave velocity models at depths above 6 km in the shallow crust based on the direct surface wave azimuthal anisotropic tomography method. The isotropic model reveals a strong correspondence between the S-wave velocity structure at depths of 0–1 km and the regional topography and lithology. The Binchuan depocenter, Zhoucheng depocenter, Xiangyun Basin, and Xihai Rift Basin are primarily composed of Quaternary deposits, which show low-velocity anomalies, while the regions with the Paleozoic shale, limestone, and basalt exhibit high-velocity anomalies. The nearly N–S orientation of fast directions from azimuthal anisotropy models are mainly controlled by the active Binchuan Fault with N–S strike as well as the NNW-oriented primary compressive stress.

关键词： Binchuan Basin Ambient noise tomography Shallow crustal structure azimuthal anisotropy

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Data merging methods for S-wave velocity and azimuthal anisotropy from different regions

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Earthquake Research Advances 2024年第4期4卷 55-60页

作者： Ying Li Yuan Gao Jianhui Tian School of Earth and Space Sciences University of Science and Technology of ChinaHefei230026China Key Laboratory of Earthquake Prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing100036China Institute of Geophysics China Earthquake AdministrationBeijing100081China

When inverting the S-wave velocity and azimuthal anisotropy from ambient noise data, it is always to obtain the partial overlapped inversion results in contiguous different regions. Merging different data to achieve a consistent model becomes an essential requirement. Based on the S-wave velocity and azimuthal anisotropy obtained from different contiguous regions, this paper introduces three kinds of methods for merging data. For data from different regions with partial overlapping areas, the merged results could be calculated by direct average weighting(DAW), linear dynamic weighting(LDW), and Gaussian function weighting(GFW), respectively. Data tests demonstrate that the LDW and GFW methods can effectively merge data by reasonably allocating data weights to capitalize on the data quality advantages in each zone. In particular, they can resolve the data smoothness at the boundaries of data areas, resulting in a consistent data model in larger regions. This paper presents the effective methods and valuable experiences that can be referred to as advancing data merging technology.

关键词： Merging methods Overlapping common area S-wave velocity azimuthal anisotropy

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Three-Dimensional Crustal Shear Wave Velocity Structure and azimuthal anisotropy Across Northern and Central Thailand From Direct Joint Inversion of Rayleigh Wave Phase Velocities

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INTERNATIONAL JOURNAL OF GEOPHYSICS 2025年第1期2025卷

作者： Saetang, Kasemsak Srisawat, Wilaiwan Nakhon Si Thammarat Rajabhat Univ Fac Educ Program Phys Nakhon Si Thammarat Thailand Watthapho Municipal Sch Sci & Technol Unit Nakhon Si Thammarat Thailand

This study presents a three-dimensional shear wave velocity (Vs) model and azimuthal anisotropy of the crust beneath northern and central Thailand derived from ambient noise tomography. Continuous seismic data from 99 broadband stations across Southeast Asia were processed to extract Rayleigh wave phase velocity dispersion curves. These curves were then used in a direct joint inversion for both isotropic Vs perturbations and azimuthal anisotropy at depths of 15-35 km. The inversion was initialized with a local 1D velocity model specifically derived for northern Thailand. Results reveal significant lateral heterogeneities in crustal structure, with Vs ranging from 3.615 to 3.675 km/s at 15-20 km depth to 3.650 to 3.720 km/s at 30-35 km depth across the study area. A prominent high-velocity anomaly (Vs > 3.675 km/s at 15-20 km depth, Vs > 3.745 km/s at 20-30 km depth, and Vs > 3.720 km/s at 30-35 km depth) is observed in the northwestern sector (18.5 degrees-19.5 degrees N, 98 degrees-101 degrees E), corresponding to the Shan-Thai terrane. The velocity contrast between the Shan-Thai and Indo-China terranes is delineated by a lateral velocity gradient, with the Shan-Thai Terrane consistently exhibiting higher velocities throughout the investigated depth range. azimuthal anisotropy patterns show complex variations, with a prominent NW-SE trend in fast polarization directions in northern Thailand, consistent across all depth ranges. The strongest anisotropy is observed in the northern Thailand, coinciding with high-velocity zones. The spatial correspondence between present-day surface kinematics, as recorded by GPS measurements, and crustal anisotropic fabric suggests a coherent deformation pattern that extends through multiple crustal levels, with pronounced expressions along terrane boundaries.

关键词： ambient noise tomography azimuthal anisotropy crustal structure shear wave velocity Southeast Asia tectonics

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Deformation of the Crust and Upper Mantle beneath the North China Craton and Its Adjacent Areas Constrained by Rayleigh Wave Phase Velocity and azimuthal anisotropy

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REMOTE SENSING 2022年第1期14卷 110-110页

作者： Xu, Xiaoming Zhang, Dazhou Huang, Xiang Cao, Xiaoman China Earthquake Adm Inst Geophys Beijing 100081 Peoples R China China Earthquake Adm Key Lab Earthquake Source Phys Beijing 100081 Peoples R China Cent South Univ Sch Geosci & Infophys Changsha 410083 Peoples R China China Univ Geosci Sch Geophys & Informat Technol Beijing 100029 Peoples R China

The North China Craton (NCC) has experienced strong tectonic deformation and lithospheric thinning since the Cenozoic. To better constrain the geodynamic processes and mechanisms of the lithospheric deformation, we used a linear damped least squares method to invert simultaneously Rayleigh wave phase velocity and azimuthal anisotropy at periods of 10-80 s with teleseismic data recorded by 388 permanent stations in the NCC and its adjacent areas. The results reveal that the anomalies of Rayleigh wave phase velocity and azimuthal anisotropy are in good agreement with the tectonic domains in the study area. Low-phase velocities appear in the rift grabens and sedimentary basins at short periods. A rotation pattern of the fast axis direction of the Rayleigh wave together with a distinct low-velocity anomaly occurs around the Datong volcano. A NW-SE trending azimuthal anisotropy and a low-velocity anomaly at periods of 60-80 s are observed subparallel to the Zhangbo fault zone. The whole lithosphere domain of the Ordos block shows a high-phase velocity and counterclockwise rotated fast axis. The northeastern margin of the Tibetan plateau is dominated by a low-velocity and coherent NW-SE fast axis direction. We infer that the subduction of the Paleo-Pacific plate and eastward material escape of the Tibetan plateau mainly contribute to the deformation of the crust and upper mantle in the NCC.

关键词： North China Craton surface wave tomography dispersion curve Rayleigh wave phase velocity azimuthal anisotropy deformation

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Velocity and azimuthal anisotropy structures beneath the Dianzhong Block and its vicinity, SE Tibetan Plateau, revealed by eikonal equation-based traveltime tomography

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TECTONOPHYSICS 2022年 839卷

作者： Liu, Shaolin Chang, Kai Yang, Dinghui Xu, Xiwei Wang, Wenshuai Yang, Shuxin Li, Mengyang Minist Emergency Management China Natl Inst Nat Hazards Beijing 100085 Peoples R China Tsinghua Univ Dept Math Sci Beijing 100084 Peoples R China Chinese Acad Sci Inst Geol & Geophys State Key Lab Lithospher Evolut Beijing 100029 Peoples R China Ningxia Univ Sch Math & Stat Yinchuan 750021 Ningxia Peoples R China

The Dianzhong Block (DZB) located on the southeastern margin of the Tibetan Plateau is an important tectonic zone characterized by the intense flow of crustal material. Although it is widely accepted that materials originating from the Tibetan Plateau migrate southeastward in the DZB and its vicinity, the flow mechanism and subsurface structures remain controversial. Here, we image the subsurface velocity and azimuthal anisotropy structures beneath the DZB and its surroundings by using eikonal equation-based tomography to study the crustal flow and deformation mechanisms. In this study, we collect high-quality seismic data from 290 broadband seismic stations and manually pick a total of 31,981 first arrivals. Our tomographic results display prominent velocity anomalies and complex azimuthal anisotropy patterns. In the upper crust, our results reveal predominant high-velocity anomalies, which are related to the Emeishan large igneous province (ELIP) and the stable Simao Block. We find strong low-velocity anomalies beneath the DZB in the middle???lower crust. The low-velocity anomalies extend southward from the Xiaojinhe Fault (XJHF) to the Red River Fault (RRF) and then rotate southeastward to the east of the Xiaojiang Fault (XJF). In addition, the inverted fast velocity directions generally follow the strike of the low-velocity anomalies. Based on these findings, we consider the existence of middle???lower crustal flow inside the DZB. Three distinct features of azimuthal anisotropy in the middle-upper crust are found around the XJF reflecting complex deformation, which may indicate different factors controlling the deformation of the XJF from the north to the south. In the lower crust and uppermost mantle, the azimuthal anisotropy beneath the RRF is relatively complex, exhibiting two patterns: one perpendicular and another parallel to the fault.

关键词： P -wave velocity azimuthal anisotropy Dianzhong Block Seismic tomography Xiaojiang Fault

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Complex Patterns of Past and Ongoing Crustal Deformations in Southern California Revealed by Seismic azimuthal anisotropy

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GEOPHYSICAL RESEARCH LETTERS 2022年第15期49卷 e2022GL100233-e2022GL100233页

作者： Wu, Shucheng Jiang, Chengxin Schulte-Pelkum, Vera Tong, Ping Nanyang Technol Univ Sch Phys & Math Sci Div Math Sci Singapore Singapore Nanyang Technol Univ Earth Observ Singapore Singapore Singapore Australian Natl Univ Res Sch Earth Sci Canberra ACT Australia Univ Colorado Cooperat Inst Res Environm Sci Boulder CO 80309 USA Univ Colorado Dept Geol Sci Boulder CO 80309 USA Nanyang Technol Univ Asian Sch Environm Singapore Singapore

We present a high-resolution P-wave azimuthally anisotropic velocity model for the upper and middle crust beneath southern California by a novel adjoint-state traveltime tomography technique. Our model reveals significant anisotropy variations between tectonic blocks that clearly reflect both past and current plate boundary deformation. In the shallow crust, seismic anisotropy is mostly controlled by the preferred alignment of microcracks related to the present N-S compressive stress;while at deeper depths (>similar to 6 km), seismic anisotropy mainly records paleofabrics formed during the long-lived Farallon subduction and later extension that have not been fully reset by the present transform motion. Interestingly, our model demonstrates distinct fast axes beneath the western Transverse Ranges from its neighboring blocks, probably reflecting the large-scale vertical axis clockwise rotation of the block. In addition, we identify layered structures with distinct anisotropy features beneath the Salton Trough, which could be a result of the current transtension.

关键词： azimuthal anisotropy seismic tomography southern California crustal deformation block rotation

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