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Characteristics of response spectra for long-periods of main-shock recordings of the Chi-Chi earthquake

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Earthquake Engineering and Engineering Vibration 2007年第2期6卷 111-121页

作者：陈勇俞言祥 institute of geophysics China Earthquake Administration

Current practice uses predictive models to extrapolate long-period response spectra based on far-field recordings in moderate and weak earthquakes. However, the spectra are not long enough and the data are often not reliable, which means that the seismic design code cannot accurately define seismic design requirements for long-period structures. The near-field recordings in the main-shock of the Chi-Chi earthquake have a large signal-to-noise ratio （SNR）, which makes them suitable for studying the long-period acceleration response spectrum up to 20 sec. The acceleration response spectra from 246 stations within 120 km of the causative fault are statistically analyzed in this paper. The influence of distance and site conditions on long-period response spectrum is discussed, and the shapes of the amplification spectra are compared with the standard spectra specified in the seismic design code of China. Finally, suggestions for future revisions to the code are proposed.

关键词： long-period main-shock recordings Chi-Chi earthquake signal-to-noise ratio acceleration response spectrum amplification spectrum

Influence of mantle convection to the crustal movement pattern in the northeastern margin of the Tibetan Plateau based on numerical simulation

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Science China Earth Sciences 2018年第11期61卷 1644-1658页

作者： Aiyu ZHU Dongning ZHANG Tao ZHU Yingxing GUO institute of geophysics China Earthquake Administration Key Laboratory of Seismic Observation and Geophysical Imaging Institute of GeophysicsChina Earthquake Administration

Based on the recent observations about the movement and rheological structure of the lithosphere and deformation pattern of the crust, we developed a three-dimensional finite element model for the northeastern margin of the Tibetan *** model considered the impacts of both external and internal conditions, including mantle convection, gravitational potential energy and block interactions. We compared the simulated surface movement rates to the observed GPS velocities, and the results revealed that crustal movement gradually decreased toward the edge of the plateau. The factors controlling this pattern are the interactions of adjacent blocks, gravitational potential energy of the plateau, and also mantle convection as well. Additionally,according to the observation that there was an apparent difference between the horizontal movement rate of the lithosphere and convective velocity of the underlying mantle, and also based on the results of seismic anisotropy studies that suggest different strengths and deformation regimes of the lithosphere in different tectonic blocks, we proposed that the impact of mantle convection on the lithosphere may have varied in space, and introduced a parameter named mantle convection intensity factor in numerical simulations. Our simulation results show consistent surface movement rates with GPS observations, which further supports the viewpoint of seismic anisotropy studies, i.e., the degree of coupling between the crust and mantle varies significantly among different blocks.

关键词： Northeastern margin of the Tibetan Plateau Crustal movement Mantle convection Numerical simulation

Mission and challenges of higher education: an interview with G.Q. Max Lu, the president of the University of Surrey

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National Science Review 2020年第6期7卷 1108-1113页

作者： Ling Wang Zhengtang Guo the institute of Geology and geophysics Chinese Academy of Sciences

The University of Surrey (referred to as Surrey hereafter) is one of the renowned universities in the UK that was established on 9 September1966 with the grant of its Royal Charter and its roots go back to Battersea Polytechnic institute, founded in 1891. Surrey is the research hub of small satellites, mobile telecommunication and artificial intelligence in Europe. In 2016, Surrey was named as ‘Univer-

关键词： Biographies

Structure of the mantle transition zone in the central and western parts of the North China Craton using the receiver function 3D Kirchhoff migration method

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Science China Earth Sciences 2024年第9期67卷 2783-2795页

作者： Min ZHU Qingju WU Jieyuan NING Ruiqing ZHANG institute of geophysics China Earthquake AdministrationBeijing 100081China institute of Theoretical and Applied geophysics Peking UniversityBeijing 100871China

Using data from the regional broadband dense temporary array deployed by the ChinArray project,we applied the three-dimensional(3D)Kirchhoff migration method of the teleseismic P-wave receiver function to investigate discontinuity structures of the mantle transition zone(MTZ)in the central and western parts of the North China Craton(NCC)using a highresolution 3D velocity model of the East Asian *** results show that the 410-km discontinuity beneath the Datong Volcano is depressed by~10 km,indicating the presence of a high-temperature anomaly near the depth of 410 km,which is likely related to small-scale mantle upwelling caused by the dehydration of the stagnant Pacific Plate in the *** upwelling of hot material provides a heat source for surface magmatic *** the Bohai Bay Basin,significant subsidence of the 660-km discontinuity is observed,and the transition zone here is extensively ***’s suggested that the anomalies in this region are related to the stagnation of the Pacific slab in the *** the thickness of the transition zone west of the North-South Gravity Lineament appears normal,we propose that the subducting front of the Pacific slab did not cross the gravity lineament in the *** comparison,the small-scale subsidence of the 660-km discontinuity and the thickening of the MTZ observed north of the Hannuoba Volcano likely indicate that the slab crossed the gravity lineament at its turning point and remained in the ***,a local thickening of the MTZ is observed in the Dabie orogenic belt of the Qinling *** is believed to be a combined effect of lithospheric delamination into the transition zone in the lower Yangtze region and the stagnation of the Pacific Plate.

关键词： North China Craton Mantle transition zone Receiver function migration Datong Volcano

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Prediction and Elimination of Multiples Based on Energy Flux Conservation Theorem and Prediction Operator Equation

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Chinese Physics Letters 2010年第5期27卷 271-274页

作者：何利刘洪丁仁伟李博 Key Laboratory of Petroleum geophysics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029

The received wave field including primaries and all of the multiples can be associated with the reflection coefficients which are only primaries by a prediction operator and two equations： the energy flux conservation equation and the prediction operator equation that is developed from the Levinson recursion and can be easily solved by Li group method under a two-dimensional condition. Given reflection coefficients, the prediction operator can be obtained by solving the prediction operator equation. By the energy flux conservation equation, the reciprocal of the prediction operator times the conjugate of it, the wave field can be predicted, in which both of the surface multiples and the internal multiples are involved. On the other hand, if the wave field is given, based on the energy flux conservation equation solved by the 2D spectral factorization, a fully automated data-driven algorithm is developed to remove the surface multiples as well as the internal multiples.

关键词： PREDICTION models ELIMINATION (Mathematics) ENERGY conservation OPERATOR equations RECURSION theory SPECTRAL theory (Mathematics) FACTORIZATION (Mathematics)

Relocation of the Yushu M_S7.1 earthquake and its aftershocks in 2010 from HypoDD

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Science China Earth Sciences 2013年第2期56卷 182-191页

作者： WANG WeiLai WU JianPing FANG LiHua WANG ChangZai institute of geophysics China Earthquake Administration

After the Yushu M S 7.1 earthquake on April 14,2010,a large number of aftershocks were recorded by the surrounding permanent network and temporary seismic *** to the distribution of stations,knowledge about velocity structure,the reliability of seismic phases,and so on,the location result from conventional method is usually of low precision,from which it is difficult to recognize the spatial and temporal distribution and the trends of aftershock *** this paper,by using teleseismic waveforms recorded by permanent station,the seismic velocity structure beneath the vicinity is obtained from receiver function stacking and inversion *** the Yushu earthquake sequences are relocated from seismic phase data by *** results show that the Yushu M S 7.1 earthquake occurred at 13 km depth;the aftershock sequences were distributed mainly in the NWW along the Garzê-Yushu fault,and most aftershocks were concentrated in a 100 km length and 5-20 km *** with the velocity structure,it can be inferred that the earthquake mainly destroys the high-velocity layer of the upper *** the west of the seismic fault near(33.3°N,96.2°E),the aftershock sequences were distributed like a straight column,suggesting there was a comminuted break from 25km depth to the ground.

关键词： Yushu earthquake double-difference algorithm aftershock distribution

Velocity structure of uppermost mantle beneath North China from Pn tomography and its implications

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Science China Earth Sciences 2003年第z2期46卷 130-140页

作者： WANG Suyun (汪素云) XU Zhonghuai (许忠淮) PEI Shunping (裴顺平) institute of geophysics China Seismological Bureau Beijing 100081 China Institute of Geophysics China Seismological Bureau Beijing 100081 China Institute of Geophysics China Seismological Bureau Beijing 100081 China

20301 Pn arrival time data are collected from the seismological bulletins of both national and regional seismic networks. Pn travel time residuals are tomographically inverted for the Pn velocity structure of uppermost mantle beneath North China. The result indicates that the average Pn velocity in North China is 7.92 km/s, and the velocity varies laterally from ?0.21 to +0.29 km/s around the average. The approximately NNE trending high and low velocity regions arrange alternatively west-eastward. From west to east we can see high velocity in the middle Ordos region, the Shanxi graben low, the Jizhong depression high, the west Shandong uplift and Bohai Sea low, and the high velocity region to the east of the Tanlu fault. In the southern boundary zone of the North China block, except for the high velocity in the Qingling Mountains region, the velocity is generally lower than the average. Obvious velocity anisotropy is seen in the Datong Cenozoic volcanic region, with the fast velocity direction in NNE-SSW. Notable velocity anisotropy is also seen around the Bay of Bohai Sea, and the fast velocity directions seem to show a rotation pattern, possibly indicating a flow-like deformation in the uppermost mantle there. The Pn velocity variations show a reversed correlation with the Earth's heat flow. The low Pn velocity regions generally show high heat flow, e.g., the Shanxi graben and Bohai Sea region. While the high Pn velocity regions usually manifest low heat flow, e.g., the region of Jizhong depression. This indicates that the Pn velocity variation in the study region is mainly aroused by the regional temperature difference in the uppermost mantle. Strong earthquakes in the crust tend to occur in the region with the abnormal low Pn velocity, or in the transition zone between high and low Pn velocity regions. The earthquakes in the low velocity region are shallower, while that in the transition zone are deeper.

关键词： North China, Pn velocity, seismic tomography, Earth's heat flow, earthquake focal depth.

Artificial ground motion compatible with specified ground shaking peaks and target response spectrum

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Earthquake Engineering and Engineering Vibration 2006年第1期5卷 41-48页

作者：赵凤新张郁山吕红山 institute of geophysics China Earthquake Administration

This article describes a hybrid simulation method to generate artificial ground motion time histories that are compatible with specified peak seismic acceleration, velocity and displacement as well as the target response spectrum of absolute acceleration. First, based on traditional methods that match the target spectrum in the frequency domain, an initial acceleration time history was synthesized to satisfy the specified peak acceleration, target spectral acceleration and intensity envelope. Second, by using the inversion formula of the seismic input to a linear single-degree-of-freedom system and by superimposing a series of narrow-band time histories in the time domain, the initial time history is further modified to allow its peak velocity and displacement to approach the targets and improve its matching precision with the target spectrum. Numerical examples are provided to demonstrate that the proposed method achieves good agreement with the target values.

关键词： artificial ground motion acceleration response spectrum ground shaking peaks spectrum matching

Artificial ground motion compatible with specified peak velocity and target spectrum

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Acta Seismologica Sinica(English Edition) 2006年第4期19卷 461-471页

作者：赵凤新张郁山 institute of geophysics China Earthquake Administration

In this paper, a method, which synthesizes the artificial ground motion compatible with the specified peak velocity as well as the target acceleration response spectrum, was proposed. In this method, firstly, an initial acceleration time history α8^（0）（t）, which satisfies the prescribed peak ground acceleration, the target spectral acceleration ST（ω, ζ）,and the specified intensity envelope, is generated by the traditional method that generates the requency domain; secondly,α8^（0）（t）is further modulated by superimposing narrow-band time histories upon it in the time domain to make its peak velocity, approach the target peak ground velocity, and at the same time to improve its fitting precision to the target spectrum. Numerical examples show that this algorithm boasts high calculation precisions.

关键词： artificial ground motion acceleration response spectrum peak velocity fitting