Study on crust-mantle tectonics and its velocity structure along the Beijing-Huailai-Fengzhen profile

ｔｕｄｙｏｎｃｒｕｓｔｍａｎｔｌｅｔｅｃｔｏｎｉｃｓａｎｄｉｔｓｖｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅａｌｏｎｇｔｈｅＢｅｉｊｉｎｇＨｕａｉｌａｉＦｅｎｇｚｈｅｎｐｒｏｆｉｌｅＺＨＩＰＩＮＧＺＨＵ（祝治平）ＸＩＡＮＫＡＮＧＺＨＡＮＧ（张先康）...     

Robust inversion analysis of local gravity anomalies caused by geological dislocation model of faults

ＲｏｂｕｓｔｉｎｖｅｒｓｉｏｎａｎａｌｙｓｉｓｏｆｌｏｃａｌｇｒａｖｉｔｙａｎｏｍａｌｉｅｓｃａｕｓｅｄｂｙｇｅｏｌｏｇｉｃａｌｄｉｓｌｏｃａｔｉｏｎｍｏｄｅｌｏｆｆａｕｌｔｓＪＩＡＮＬＩＡＮＧＨＵＡＮＧ（黄建梁）ＣＨＯＮＧＹＡＮＧＳＨＥＮ（申...     

3-D structural reconstruction of Moho in the Tangshan earthquake area by using inversion of curved interface

３ＤｓｔｒｕｃｔｕｒａｌｒｅｃｏｎｓｔｒｕｃｔｉｏｎｏｆＭｏｈｏｉｎｔｈｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅａｒｅａｂｙｕｓｉｎｇｉｎｖｅｒｓｉｏｎｏｆｃｕｒｖｅｄｉｎｔｅｒｆａｃｅＸＩＡＯＬＩＮＧＬＡＩ（赖晓玲）ＸＩＡＮＫＡＮＧＺＨＡＮＧ...     

Rupture process of November 6,1988,Lan-cang-Gengma,Yunnan,China,earthquake of M_s=7.6 using empirical Green’s function de-convolution method

ＲｕｐｔｕｒｅｐｒｏｃｅｓｏｆＮｏｖｅｍｂｅｒ６,１９８８,ＬａｎｃａｎｇＧｅｎｇｍａ,Ｙｕｎｎａｎ,Ｃｈｉｎａ,ｅａｒｔｈｑｕａｋｅｏｆＭｓ＝７．６ｕｓｉｎｇｅｍｐｉｒｉｃａｌＧｒｅｎ’ｓｆｕｎｃｔｉｏｎｄｅｃｏｎｖｏｌｕｔｉｏｎｍｅｔｈｏｄ...     

Application research of seismic method in assessment of active fault

ＡｐｐｌｉｃａｔｉｏｎｒｅｓｅａｒｃｈｏｆｓｅｉｓｍｉｃｍｅｔｈｏｄｉｎａｓｅｓｍｅｎｔｏｆａｃｔｉｖｅｆａｕｌｔＭＩＮＧＣＡＩＸＵ（徐明才）ＪＩＮＧＨＵＡＧＡＯ（高景华）ＭＩＮＧＴＡＯＣＨＡＩ（柴铭涛）ＧＵＡＮＧＫＥＷＡＮＧ（王广科）ＪＩ...     

The anomalous reactions of the geomagnetic horizontal field transfer functions before Tangshan earthquake

ＴｈｅａｎｏｍａｌｏｕｓｒｅａｃｔｉｏｎｓｏｆｔｈｅｇｅｏｍａｇｎｅｔｉｃｈｏｒｉｚｏｎｔａｌｆｉｅｌｄｔｒａｎｓｆｅｒｆｕｎｃｔｉｏｎｓｂｅｆｏｒｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅＳＨＡＯＪＩＮＧＧＯＮＧ（龚绍京）ＨＵＡＲＡＮＣＨＥＮ（...     

Pore presure in deep bore-holes:Its measurement and relation with seismic activities

Ｐｏｒｅｐｒｅｓｕｒｅｉｎｄｅｐｂｏｒｅｈｏｌｅｓ：ＩｔｓｍｅａｓｕｒｅｍｅｎｔａｎｄｒｅｌａｔｉｏｎｗｉｔｈｓｅｉｓｍｉｃａｃｔｉｖｉｔｉｅｓＪＩＡＮＬＩＧＡＯ（高建理）ＳＨＩＺＯＮＧＳＵＮ（孙世宗）ＪＩＡＮＭＩＮＤＩＮＧ（丁健民）ＧＵ...     

scattering and refracting of plane strain wave by a cylindrical inclusion in fluidsaturated soils

ＳｃａｔｅｒｉｎｇａｎｄｒｅｆｒａｃｔｉｎｇｏｆｐｌａｎｅｓｔｒａｉｎｗａｖｅｂｙａｃｙｌｉｎｄｒｉｃａｌｉｎｃｌｕｓｉｏｎｉｎｆｌｕｉｄｓａｔｕｒａｔｅｄｓｏｉｌｓＹＡＹＵＡＮＨＵ（胡亚元）ＬＩＺＨＯＮＧＷＡＮＧ（王立忠）ＹＵＮＭＩＮＣＨ...     

Experimental studies of focal mechanism based on the dynamic process of energy release

ＥｘｐｅｒｉｍｅｎｔａｌｓｔｕｄｉｅｓｏｆｆｏｃａｌｍｅｃｈａｎｉｓｍｂａｓｅｄｏｎｔｈｅｄｙｎａｍｉｃｐｒｏｃｅｓｏｆｅｎｅｒｇｙｒｅｌｅａｓｅＸＩＭＩＮＧＺＨＥＮＧ１）（郑熙铭）ＨＯＵＸＩＵＧＡＯ２）（高后秀）ＹＵＱＩＮＹＡＮＧ２）（杨渝...     

Study of the anomaly of seismic fractal spectrum before strong earthquakes

ＳｔｕｄｙｏｆｔｈｅａｎｏｍａｌｙｏｆｓｅｉｓｍｉｃｆｒａｃｔａｌｓｐｅｃｔｒｕｍｂｅｆｏｒｅｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓＬＩＮＧＲＥＮＺＨＵ１）（朱令人）ＳＨＩＹＯＮＧＺＨＯＵ１）（周仕勇）ＭＡＬＩＮＧＹＡＮＧ１）（杨马陵）ＨＡＩＴ...     

Artificial ground motion compatible with specified peak velocity and target spectrum

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.     

Empirical evaluation of peak ground velocity and displacement as a function of elastic spectral ordinates for design

In the framework of the revision of Part 1 of Eurocode 8, this study aims at developing new empirical correlations to compute peak values of ground velocity (PGV) and displacement (PGD) as a function of elastic spectral ordinates for design. At variance with the expressions for PGV and PGD currently adopted in the Eurocode 8, based solely on the peak ground acceleration (PGA), in this paper reference is made to spectral ordinates of the short and intermediate period range, namely S_s, which is the constant acceleration spectral ordinate, and S₁, which is the spectral ordinate at 1 s. On the one hand, a relationship between PGV and the product (S_s?S₁) was found based on the regression analysis on a high‐quality strong‐motion dataset. On the other hand, the PGD was estimated by extrapolating to long periods the constant displacement branch of the elastic response spectrum, introducing a correlation between the corner period T_D and S₁. For this purpose, results of a long period probabilistic seismic hazard assessment study for Italy, encompassing low to high seismicity areas, were considered. Furthermore, verification of the proposed relationship against strong‐motion records was carried out, and differences justified in terms of the concept of uniform hazard spectrum.     

Source parameters of bohai earthquake, July 18, 1969 and yongshan earthquake, May 11, 1974 determined by synthetic seismograms of teleseismic P waves

The source parameters of the Bohai Sea earthquake, July 18, 1969 and Yongshan, Yunnan earthquake, May 11, 1974 were determined by full — wave theory synthetic seismograms of teleseismic P waves. P+pP+sP wereform were calculated with WKBJ approximation and real integral paths. One — dimensional unilateral, finite propagation source was also considered. By trail — and — error in comparing the theoretical seismograms with the observational ones of WWSSN stations, the source parameters were obtained as follow: for Bohai earthquake, φ=195°, δ=85°, λ=65°,M _o=0.9×10¹⁹Nm,L=59.9km.V _R=3.5km/s, ∧ _R =160°; for Yongshan earthquake, φ=240°, δ=80°, ∧=150°,M _o=1.3×10¹⁸Nm,L=48.8km,V _R=3km/s, ∧ _R =−10°, where φ is strike, δ dip angle, λ slip angle,M _o seismic moment,L rupture length,V _R rupture propagation speed. As III type fractures the faulting propagated along the fault planes, and ∧ _R is the angle from the strike to the propagation direction. Yongshan earthquake showed complexity in its focal process, having four sub—ruptures during the first 60 seconds. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 1–8, 1991.     

Note on the dependence of Pc3-4 activity on the solar wind velocity

Various models that describe the dependence of pulsation amplitude A on the solar wind velocity V are discussed. Phenomenological considerations and experimental data count in favour of a model of the form A/A₀=(V/V₀) exp (-V₀/V). The linear model A=a+bV which is common in the literature gives negative values of amplitude as V->0, which is strange from the physical point of view. The possibility of modifying the linear model by including critical phenomena is discussed.     

Determination of horizontal and vertical design spectra based on ground motion records at Lali tunnel,Iran

Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spectra, even if the diagrams recorded at the site in question. In order to design earthquake resistant structures, we, instead, suggest constructing a design spectrum using a set of spectra that have common characteristics to the recorded acceleration diagrams at a particular site and smoothing the associated data. In this study, we conducted a time history analysis and determined a design spectrum for the region near the Lali tunnel in Southwestern Iran. We selected 13 specific ground motion records from the rock site to construct the design spectrum. To process the data, we first applied a base-line correction and then calculated the signal-to-noise ratio (R_SN) for each record. Next, we calculated the Fourier amplitude spectra of the acceleration pertaining to the signal window (1), and the Fourier amplitude spectra of the associated noise (2). After dividing each spectra by the square root of the selected window interval, they were divided by each other (1 divided by 2), in order to obtain the R_SN ratio (filtering was also applied). In addition, all data were normalized to the peak ground acceleration (PGA). Next, the normalized vertical and horizontal responses and mean response spectrum (50%) and the mean plus-one standard deviation (84%) were calculated for all the selected ground motion records at 5% damping. Finally, the mean design spectrum and the mean plus-one standard deviation were plotted for the spectrums. The equation of the mean and the above-mean design spectrum at the Lali tunnel site are also provided, along with our observed conclusions.     

Seismic motion and response prediction alternatives

Statistical methods are available which predict the maximum response of simple oscillators given the peak acceleration (A_p), peak velocity (V_p) or peak displacement (D_p) of seismic ground motions. An alternative parameter, namely an ordinate (or ordinates) of the Fourier amplitude spectrum of ground motion acceleration, FS(f), may in fact be a preferred predictor of peak response, especially in a frequency range close to f. Other statistical methods (attenuation laws) use distance R and other parameters such as magnitude (M), Modified Mercalli epicentral Intensity (I_o) and Modified Mercalli site Intensity (MMI or I_s) to predict spectral velocity (S_v(f)), etc. In using such approaches, it is most desirable to know the total uncertainty in the predicted peak response of the system given the starting parameter values. An extensive strong motion data set is used to study these questions, The most direct prediction models are found to be preferable (have lower prediction dispersion) but data may not be available in all regions to permit their use.     

黄河阶地特征与地震动参数的相关性研究

在分析已有资料的基础上划分了兰州盆地与建设工程分布密切相关的T₀、T₁、T₂、T₃和T₄级黄河阶地,建立201个土层地震反应模型。通过一维等效线性化计算和反应谱分析,得出兰州盆地沉积阶地50年超越概率10%地表地震动参数,分析阶地高度和v_S≤500 m/s覆盖层厚度特征与地震动参数峰值加速度Am和加速度反应谱特征周期T_g的相关性。表明兰州盆地T₀~T₂阶地覆盖层厚度与50年超越概率10%A_m呈正相关,T₃及以上阶地覆盖层厚度对A_m增大有明显的减小作用。T_g值随T₀~T₃阶地覆盖层厚度的增加而变大,当覆盖层厚度进一步变大,T_g值不再同步增大,阶地覆盖层厚度对T_g的影响是有限的,阶地海拔高度与地表50年超越概率10%地震动参数没有关系。     

An energy approach to sliding of single-span simply supported slab-on-girder steel highway bridges with damaged bearings

This paper investigates the non-linear inelastic seismic response of existing single-span simply supported bridges having bearings which can remain stable and slide after their anchor bolts are ruptured. A simplified equivalent model is developed for the inelastic analysis of these single-span simply supported bridges. Non-linear inelastic time-history analyses are conducted for various acceleration inputs. It is found that narrower bridges with longer spans may have considerable sliding displacements and fall off their supports if adequate seat width is not provided. It is also found that for the same ratio of friction coefficient to peak ground acceleration, the sliding displacement of a structural system is linearly proportional to the amplitude of the peak ground acceleration beyond a certain threshold value. This is also demonstrated analytically from an energy approach point of view. The distribution of the energy content of an earthquake, which is related to its velocity time history, can be an indication of the propensity of an earthquake to cause high sliding displacements. Ground motions with high frequency content or high A_p/V_p ratio may produce smaller sliding displacements than ground motions with relatively lower A_p/V_p ratios.     

Critical response of structures to multicomponent earthquake excitation

This paper aims to develop an improved understanding of the critical response of structures to multicomponent seismic motion characterized by three uncorrelated components that are defined along its principal axes: two horizontal and the vertical component. An explicit formula, convenient for code applications, has been derived to calculate the critical value of structural response to the two principal horizontal components acting along any incident angle with respect to the structural axes, and the vertical component of ground motion. The critical response is defined as the largest value of response for all possible incident angles. The ratio r_cr/r_srss between the critical value of response and the SRSS response—corresponding to the principal components of ground acceleration applied along the structure axes—is shown to depend on three dimensionless parameters: the spectrum intensity ratio γ between the two principal components of horizontal ground motion characterized by design spectra A(T_n) and γA(T_n); the correlation coefficient α of responses r_x and r_y due to design spectrum A(T_n) applied in the x‐ and y‐directions, respectively; and β = r_y/r_x. It is demonstrated that the ratio r_cr/r_srss is bounded by 1 and . Thus the largest value of the ratio is , 1.26, 1.13 and 1.08 for γ = 0, 0.5, 0.75 and 0.85, respectively. This implies that the critical response never exceeds times the result of the SRSS analysis, and this ratio is about 1.13 for typical values of γ, say 0.75. The correlation coefficient α depends on the structural properties but is always bounded between −1 and 1. For a fixed value of γ, the ratio r_cr/r_srss is largest if β = 1 and α = ±1. The parametric variations presented for one‐storey buildings indicate that this condition can be satisfied by axial forces in columns of symmetric‐plan buildings or can be approximated by lateral displacements in resisting elements of unsymmetrical‐plan buildings. Copyright © 2000 John Wiley & Sons, Ltd.