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Building the community velocity model in the Sichuan-Yunnan region, China: Strategies and progresses

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Science China Earth Sciences 2020年第9期63卷 1425-1428页

作者： huajian yao Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Anhui Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng 233500China CAS Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China

*** The subduction and collision between the Indian plate and the Eurasian plate resulted in large-scale deformation of crust and upper mantle material in the Tibetan Plateau and its *** has been transported from the ... 详细信息

关键词： mantle Eurasian plateau

Shear wave velocity structure of the crust and upper mantle in Southeastern Tibet and its geodynamic implications

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Science China Earth Sciences 2020年第9期63卷 1278-1293页

作者： Zhiqi ZHANG huajian yao Yan YANG Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng 233500China CAS Center for Excellence in Comparative Planetology USTC Hefei 230026China

Southeastern Tibet,which has complex topography and strong tectonic activity,is an important area for studying the subsurface deformation of the Tibetan *** the two-station method on 10-year teleseismic Rayleigh wave data from 132 permanent stations in the southeastern Tibetan Plateau,which incorporates ambient noise data,we obtain the interstation phase velocity dispersion data in the period range of 5–***,we invert for the shear wave velocity of the crust and upper mantle through the direct 3-D inversion *** find two low-velocity belts in the mid-lower *** belt is mainly in the SongPan-GangZi block and northwestern part of the Chuan-Dian diamond block,whereas the other belt is mainly in the Xiaojiang fault zone and its eastern part,the Yunnan-Guizhou *** low-velocity belt in the Xiaojiang fault zone is likely caused by plastic deformation or partial melting of felsic rocks due to crustal ***,the significant positive radial anisotropy(VSH>VSV)around the Xiaojiang fault zone further enhances the amplitude of low velocity anomaly in our *** crustal low-velocity zone also extends southward across the Red River fault and farther to northern Vietnam,which may be closely related to heat sources in the upper *** two low-velocity belts are separated by a high-velocity zone near the Anninghe-Zemuhe fault system,which is exactly in the inner and intermediate zones of the Emeishan large igneous province(ELIP).We find an obvious high-velocity body situated in the crust of the inner zone of the ELIP,which may represent maficultramafic material that remained in the crust when the ELIP *** the upper mantle,there is a large-scale low-velocity anomaly in the Indochina and South China blocks south of the Red River *** low-velocity anomaly gradually extends northward along the Xiaojiang fault zone into the Yangtze Craton as depth *** our velocity model,we think that southeastern Tibet is

关键词： Southeastern Tibet Surface wave tomography Shear wave velocity structure Xiaojiang fault system Emeishan large igneous province Asthenospheric upwelling

Monitoring of velocity changes based on seismic ambient noise: A brief review and perspective

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Earth and Planetary Physics 2020年第5期4卷 532-542页

作者： Qing-Yu Wang huajian yao University Grenoble Alpes CNRSISTerreGrenobleFrance Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Chinese Academy of Sciences Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng Anhui 233500China

Over the past two decades,the development of the ambient noise cross-correlation technology has spawned the exploration of underground *** addition,ambient noise-based monitoring has emerged because of the feasibility of reconstructing the continuous Green’s *** the physical properties of a subsurface medium by tracking changes in seismic wave velocity that do not depend on the occurrence of earthquakes or the continuity of artificial sources dramatically increases the possibility of researching the evolution of crustal *** this article,we outline some state-of-the-art techniques for noise-based monitoring,including moving-window cross-spectral analysis,the stretching method,dynamic time wrapping,wavelet cross-spectrum analysis,and a combination of these measurement methods,with either a Bayesian least-squares inversion or the Bayesian Markov chain Monte Carlo *** briefly state the principles underlying the different methods and their pros and *** elaborating on some typical noisebased monitoring applications,we show how this technique can be widely applied in different scenarios and adapted to multiples *** list classical applications,such as following earthquake-related co-and postseismic velocity changes,forecasting volcanic eruptions,and tracking external environmental forcing-generated transient *** monitoring cases having different targets at different scales,we point out the applicability of this technology for disaster prediction and early warning of small-scale reservoirs,landslides,and so ***,we conclude with some possible developments of noise-based monitoring at present and summarize some prospective research *** improve the temporal and spatial resolution of passive-source noise monitoring,we propose integrating different methods and seismic *** interdisciplinary collaboration is indispensable for comprehensively interpreting the observed changes.

关键词： ambient noise correlation noise-based monitoring seismic wave velocity changes the evolution of physical properties of the crust

Lithospheric structure and deformation in SE Tibet revealed by ambient noise and earthquake surface wave tomography: Recent advances and perspectives

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Earthquake Science 2012年第5期25卷 371-383页

作者： huajian yao Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space SciencesUniversity of Science and Technology of China

High-resolution lithospheric structure is essential for understanding the tectonic evolution and deformation patterns of the southeastern Tibetan plateau. This is now possible due to recent advances in ambient noise and earthquake surface wave tomography, and great improvements in data coverage from dense portable array stations deployed in SE Tibet. In this review paper, I first give a brief overview of the tomographic methods from ambient noise and earthquake surface waves, and then summarize the major findings about the lithospheric structure and deformation in SE Tibet revealed by ambient noise and earthquake surface wave tomography as well as by other seismic and geophysical observations. These findings mainly include the 3-D distribution of mechanically weak zones in the mid-lower crust, lateral and vertical variations in radial and azimuthal anisotropy, possible interplay of some fault zones with crustal weak zones, and importance of strike-slip faulting on upper crustal deformation. These results suggest that integration of block extrusion in the more rigid upper-middle crust and channel flow in the more ductile mid-lower crust will be more compatible with the current geophysical observations. Finally I discuss some future perspective researches in SE Tibet, including array-based tomography, joint inversion using multiple seismic data, and integration of geodynamic modeling and seismic observations.

关键词： SE Tibet lithospheric structure deformation ambient noise earthquake surface waves

Seismic airgun exploration of continental crust structures

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Science China Earth Sciences 2017年第10期60卷 1739-1751页

作者： CHEN Yong WANG BaoShan yao huajian School of Earth Sciences and Engineering Nanjing University Nanjing 210046 China Institute of Earthquake Science China Earthquake Administration Beijing 100036 China Key Laboratory of Seismic Observation and Geophysical Imaging Institute of Geophysics China Earthquake Administration Beijing 100081 China Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China National Geophysical Observatory at Mengcheng University of Science and Technology of China Hefei 230026 China

The active sources generate seismic waves transmitting appropriate through the deep is underground key and can be used to image Abstract high-resolution subsurface ***,an seismic source the factor to active source *** order to study the structure of continental crust and its temporal variations,we selected an artificial seismic source generated from releasing air bubbles in water(airgun source hereinafter)out of a variety and of artificial sources like the is explosion,new electronic sparkers,source hammering,eccentric proven vibration,be heavy-duty train vibration,vibroseis *** Three source Fixed a type of artificial that have been to environmentally friendly,safe,and highly *** western Signal China Transmission and Stations(FASTS)have been for built a few years ago in Yunnan,Xinjiang,and Gansu provinces in have been continuously them running several *** waves generated away by the the airgun sources are highly seismic reproducible waves and stacking in of can produce can good seismograms on 1300 stations km far from source,for instance,an produced Xinjiang FASTS be well about recorded 60 nearly away after 5000 stacking,China covering area of 6 million km2 and penetrating down to of a depth of *** about 10 FASTSs in would enable long-term illuminate continuous subsurface underground structures,monitoring can all 9.6 million km2 of land *** from airgun sky active sources as lanterns to we achieve the situation with"Beidou surveys the and lantern illuminates underground".

关键词： Continental crust structure Airgun Green Environmental protection Seismic surveys

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

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Earthquake Science 2015年第1期28卷 59-69页

作者： huajian yao Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of China National Geophysical Observatory at Mengcheng

Seismic anisotropy provides important constraints on deformation patterns of Earth＇s material. Rayleigh wave dispersion data with azimuthal anisotropy can be used to invert for depth-dependent shear wavespeed azimuthal anisotropy, therefore reflecting depth-varying deformation patterns in the crust and upper mantle. In this study, we propose a two-step method that uses the Neighborhood Algorithm （NA） for the point-wise inversion of depth-dependent shear wavespeeds and azimuthal anisotropy from Rayleigh wave azimuthally anisotropic dispersion data. The first step employs the NA to estimate depth- dependent Vsv （or the elastic parameter L） as well as their uncertainties from the isotropic part Rayleigh wave dispersion data. In the second step, we first adopt a difference scheme to compute approximate Rayleigh-wave phase velocity sensitivity kernels to azimuthally anisotropic parameters with respect to the velocity model obtained in the first step. Then we perform the NA to estimate the azimuthally anisotropic parameters Gc/L and Gs/L at depths separately from the corresponding cosine and sine terms of the azimuthally anisotropic dispersion data. Finally, we compute the depth-dependent magnitude and fast polariza- tion azimuth of shear wavespeed azimuthal anisotropy. The use of the global search NA and Bayesian analysis allows for more reliable estimates of depth-dependent shear wavespeeds and azimuthal anisotropy as well as their *** illustrate the inversion method using the azimuthally anisotropic dispersion data in SE Tibet, where we find apparent changes of fast axes of shear wavespeed azimuthal anisotropy between the crust and uppermost mantle.

关键词： Azimuthal anisotropy Shear wavespeed Rayleigh wave Neighborhood Algorithm

Effect of lateral heterogeneity on 2-D Rayleigh wave ZH ratio sensitivity kernels based on the adjoint method: Synthetic and inversion examples

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Earth and Planetary Physics 2020年第5期4卷 513-522页

作者： Ting Lei huajian yao Chao Zhang Laboratory of Seismology and Physics of the Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng 233500China Chinese Academy of Sciences Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China College of Oceanography Hohai UniversityNanjing 245700China

The ratio between vertical and radial amplitudes of Rayleigh waves(hereafter,the Rayleigh wave ZH ratio)is an important parameter used to constrain structures beneath seismic *** previous studies have explored crust and upper mantle structures by joint inversion of the Rayleigh wave ZH ratio and surface wave ***,all these studies have used a 1-D depth sensitivity kernel,and this kernel may lack precision when the structure varies a great deal ***,we present a systematic investigation of the two-dimensional(2-D)Rayleigh wave ZH ratio kernel based on the adjoint-wavefield method and perform two synthetic tests using the new *** 2-D ZH ratio kernel is consistent with the traditional 1-D sensitivity kernel but has an asymmetric pattern with a preferred orientation toward the *** predominant effect caused by heterogeneity can clearly be seen from kernels calculated from models with 2-D heterogeneities,which confirms the necessity of using the new 2-D kernel in some complex *** tests using synthetic data show that the 2-D ZH ratio kernel has the potential to resolve small anomalies as well as complex lateral structures.

关键词： Rayleigh wave ZH ratio adjoint-wavefield method 2-D sensitivity kernel tomography

Massive lithospheric delamination in southeastern Tibet facilitating continental extrusion

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National Science Review 2022年第4期9卷 23-32页

作者： Jikun Feng huajian yao Ling Chen Weitao Wang Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space SciencesUniversity of Science and Technology of China CAS Center for Excellence in Comparative Planetology University of Science and Technology of China Mengcheng National Geophysical Observatory University of Science and Technology of China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of Sciences CAS Center for Excellence in Deep Earth Science Institute of Geophysics China Earthquake Administration

Significant left-lateral movement along the Ailao Shan-Red River fault accommodated a substantial amount of the late Eocene to early Miocene India-Asia ***,the activation of this critical strike-slip fault remains poorly ***,we show key seismic evidence for the occurrence of massive lithospheric delamination in southeastern *** novel observation of reflected body waves(e.g.P410P and P660P) retrieved from ambient noise interferometry sheds new light on the massive foundered lithosphere currently near the bottom of the mantle transition zone beneath southeastern *** integrating the novel seismic and pre-existing geochemical observations,we highlight a linkage between massive lithospheric delamination shortly after the onset of hard collision and activation of continental extrusion along the Ailao Shan-Re d River *** information provides critical insight into the early-stage evolution of the India-Asia collision in southeastern Tibet,which has significant implications for continental collision and its intracontinental response.

关键词： ambient noise interferometry reflected body waves lithospheric delamination India-Asia collision Indochina extrusion

Crustal azimuthal anisotropy in the trans-North China orogen and adjacent regions from receiver functions

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Science China Earth Sciences 2018年第7期61卷 903-913页

作者： Yan YANG huajian yao Ping ZHANG Ling CHEN Laboratory of Seismology and Physics of Earth's Interior and School of Earth and Space Sciences University of Science and Technology of China Mengcheng National Geophysical Observatory University of Science and Technology of China Institute of Geology and Geophysics Chinese Academy of Sciences

The North China Craton(NCC) is an important part of eastern China. Recent studies have shown that the eastern NCC(ENCC) has undergone significant lithospheric thinning and destruction since the late Mesozoic. Destruction of the cratonic lithosphere is necessarily accompanied by crustal deformation. Therefore, a detailed crustal deformation model can provide basic observational constraints for understanding the process and mechanisms of the destruction of the NCC. In this study, we estimated the crustal azimuthal anisotropy beneath 198 broadband stations in the NCC with a joint analysis of Ps waves converted at the Moho from radial and transverse receiver function data. We also performed a harmonic analysis to test the reliability of the measured anisotropy. We obtained robust crustal azimuthal anisotropy beneath 23 stations that are mostly located on the western margin of the Bohai Bay Basin, Yin-Yan orogenic belt, and Taihang Mountains, which reflects the crustal deformation characteristics in those regions. The crustal shear wave splitting time was found to range from 0.05 s to 0.68 s, with an average value of 0.23 s, which reveals a distinct crustal anisotropy in the Trans-North China Orogen(TNCO) and its adjacent areas. Our analysis of the results suggests that the strong NW-SE tectonic extension in the late Mesozoic and Cenozoic played an important role in crustal anisotropy in this region. In addition, the E-W trending crustal anisotropy on the margin of the Bohai Bay Basin indicates an effect of the ENE-WSW trending horizontal principal compressive stress. The crustal anisotropy in the Yin-Yan orogenic belt may be an imprint of the multiple-phase shortening of a dominant N-S direction from the early-to-middle Jurassic to the Early Cretaceous. Stations in the Taihang Mountains show large splitting times and well-aligned NW-SE fast directions that correlate with those measured from SKS splitting and that are possibly related to the lithospheric modification and

关键词： North China Craton Receiver functions Crust Azimuthal anisotropy