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1.
Tong-En Mao Zhan-Po Liu Chang-Fang Xu Hong-Kui Zhang Su-Rong Yu Meng-Jing Lei 《地震学报(英文版)》1998,11(2):189-196
The 1° × 1° distribution map of crust-mantle structural ratio R for the lithosphere along the Longitudinal Seismic Belt of China has been compiled using computer based on the results of
geophysical prospecting by previous researchers, and the latest results by the present authors. Based on this map, an insight
into the structural features of the crust-mantle assemblage along the Longitudinal Seismic Belt has been gained, while their
relation to seismic activity and the distributions of geothermal flux and intracrustal high conductivity-low velocity layers,
as well as their tectonic effect to seismicity have been discussed.
Contribution No. 97A0079, Institute of Geophysics, State Seismological Bureau, China. 相似文献
2.
根据前人和作者最新深部地球物理探测研究成果，完成了中国东部大陆（１０５°Ｅ以东）１°×１°壳－幔结构比值Ｒ（Ｒ＝Ｃ／Ｌ，Ｃ为地壳厚度，Ｌ为岩石层厚度）分布图的编绘．研究了Ｒ值分布与东部大陆岩石层分块、大地构造形态特征；Ｒ值分布与东部大陆地震活动的非均匀性特征；Ｒ值分布的动力学内涵．结果表明：１．Ｒ值等值线特征反映了岩石层块体划分、大地构造形态，Ｒ值特征与岩石层块体划分、大地构造形态有其深部成因上的联系；２．高Ｒ值区对应地震高活动区，因而Ｒ值可作为地震区划、地震危险性评定的定量指标，Ｒ值是地震活动的动力因子． 相似文献
3.
Introduction At the juncture of Qinghai-Xizang, Ordos and Alxa blocks lies the Qinghai-Xizang plateau, an area with complicated topographic and morphologic features, strong tectonic activities and frequent earthquakes (many large-magnitude earthquakes have taken place), has become a focal area for geoscience study. Many geophysical and geological surveys have been carried out in and around the area, such as deep seismic sounding (DSS), gravimetry, magnetotelluric sounding, magnetic anomaly … 相似文献
4.
本文理论分析了具有不同沉积层和壳幔过渡带结构的接收函数及其相关的H-κ叠加结果,然后采用接收函数H-κ叠加和波形反演方法获得了具有复杂构造演化历史的中北安纳托利亚板块的地壳厚度(H)、V_P/V_S(κ)和V_S结构.理论分析表明:厚的沉积层或沉积层和厚的壳幔过渡带共存都会使H-κ叠加失效;渐变型壳幔过渡带导致H-κ叠加的H位于过渡带中间,且随着频率增大逐渐靠近过渡带上方;倒转型壳幔过渡带导致H-κ叠加具有多极值,其结果可能反应过渡带内最大波阻抗界面上的地壳结构;1km·s~(-1)的V_P变化会导致H-κ叠加的H变化7km,而κ变化较小.实际资料分析表明:中北安纳托利亚H,κ和V_S具有强烈的横向不均匀性,大部分区域沉积层厚度0.5km,局部地区壳幔过渡带厚度3km;北安纳托利亚断层切穿地壳,在局部地区可能存在流体;研究区存在残留古老的小陆块体.本文研究表明,仔细分析接收函数波形和其随方位角的变化特征且用其他地震学方法进行约束,有助于采用H-κ叠加方法获取复杂地壳结构信息. 相似文献
5.
Two well-known methodologies have been used, for the first time, to derive a detailed and reliable lithospheric model of the Adriatic Plate, consistent with the thus far available data: non linear inversion of phase and group velocity dispersion curve obtained from surface-wave tomography, and body-waves tomography. To carry out the body-waves tomography, about 16500 P phases and 2000 S phases from 1219 seismic events, 73 seismic stations located at the border of the investigated region and a vertically heterogeneous starting model derived from the nonlinear inversion of average dispersion measurements, are used. The 3-D velocity model of the upper lithosphere, obtained from the combined analysis, shows a rather clear structural anomaly on the northeastern side, where the crust is thicker, and an uprising of the top of the lid in the northern part of the plate with a very thin, if any, transition zone from crust to mantle.Acknowledgement We are grateful to Bruno Alessandrini and Luisa Filippi (National Seismic Service, Rome – Italy) for providing the computer code SIMULPS and for their very useful advice on the local earthquakes tomography method. This work has been supported by the Italian project MURST-COFIN prot. 2001048324-001 (2001). 相似文献
6.
We have employed 10 digital records and computed the spectral magnitude and the seismic radiated energy for 18 large earthquakes
(M
s≥6) occurred in Eur-asian belt during 1986–1989. The nine digital stations (CD-SN) distribute all over China and one in Germany.
The spectral magnitudes of various period have different stability among stations. The stability is better for maximum spectral
magnitudemi and seismic radiated energyE, their differences among stations are smaller, especially for the stations where the ray path main penetrates the low mantle.
But the stability of corner period is usually not good. The relation between seismic radiated energy and seismic moment magnitudeM
w is lg (E)=1.5Mw+c, wherec is a constant. The maximum spectral magnitudemi=M
w+0.1, it is consistant with theoretical prediction.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 418–426, 1993.
This work supported by the Deutsche Forschungsgemeinschaft, Bonn, F. R. Germany. The support is grateful acknowledge. 相似文献
7.
The Sichuan-Yunnan Block (SYB) is located at the SE margin of the Qinghai-Tibetan Plateau (TP). Under the influence of the southeastward movement of material originated from the TP, intense crustal deformation, frequent seismic activity, and complex geological structures are observed in the SYB. The Lijiang-Xiaojinhe fault (LXF) goes through the central part of the SYB, dividing it into two blocks from north to south, and forming an intersecting fault system with the surrounding faults. This paper firstly introduces the morphology and the nature of the LXF, the distribution of the regional surface displacements and the focal mechanisms, and then analyzes the medium deformation and the effects of faults. Moreover, according to the regional tectonics and geophysical patterns, the paper discusses the characteristics of the north-south blocks of the SYB and the abrupt change of deep structure along the LXF zone. Since seismic anisotropy is an essential property for detecting crustal stress, deep structures and dynamical mechanisms, this paper is dedicated to the advances in seismic anisotropy at different depths and different scales in the study area. There are noteworthy differences in the anisotropic features between the north part and the south part of the SYB, possibly associated with a clear boundary adjacent to the LXF. Such phenomenon suggests some close correlation between anisotropic zoning boundary and the LXF, although this boundary is not consistent with the LXF in strike. The results from the deformation of the crust and the upper mantle elucidate the distribution patterns of the crust-mantle coupling in the north part and the crust-mantle decoupling in the south part, even though this conclusion needs to be further verified by more studies. Presently, the scientific understanding of the deep tectonics and the media deformation around the “generalized” LXF i.e. the LXF with the Jinpingshan fault on its eastern side, is still insufficient, and related equivocal topics deserve more in-depth studies. 相似文献
8.
Peak and integral seismic parameters of L��Aquila 2009 ground motions: observed versus code provision values 总被引：1，自引：1，他引：0
A. Masi L. Chiauzzi F. Braga M. Mucciarelli M. Vona R. Ditommaso 《Bulletin of Earthquake Engineering》2011,9(1):139-156
The M
w 6.3 L’Aquila earthquake of April 6, 2009 hit a wide area of the Abruzzo region (Central Italy). The epicentre of the main
shock was very close to the urban centre of L’Aquila, the regional capital, with an epicentral distance less than 10 km. It
was the strongest earthquake ever recorded in Italy which has provided ground motion recordings from accelerometric stations
located in close proximity to the epicentre. Because of this, several remarkable results can be achieved by analysing the
strong motion recorded signals in terms of peak (PGA, PGV and PGD) and integral (Housner Intensity, I
H) seismic parameters. Additionally, an alternative time-domain representation of recorded signals has been used to furnish
a rapid comparison of traces recorded at different stations and along different directions. Some comparisons between the response
spectra derived from the recordings and the elastic demand spectra provided in the new seismic Italian code have also been
performed. PGA recorded values are very high and generally higher than code values for seismic actions with return period
T
R = 475 years. In some cases, this also happens for seismic actions with T
R up to 2,475 years. With regard to I
H, recorded values are generally higher for T
R = 475 years, whilst they are remarkably lower for T
R = 2,475 years. Accurate analyses have been carried out in the article to better understand the above differences and their
significance and implications. 相似文献
9.
The characteristics of spatio-temporal seismicity evolution before the Wenchuan earthquake are studied. The results mainly involve in the trend abnormal features and its relation to the Wenchuan earthquake. The western Chinese mainland and its adjacent area has been in the seismically active period since 2001, while the seismic activity shows the obvious quiescence of M≥?7.0, M≥?6.0 and M?≥5.0 earthquakes in Chinese mainland. A quiescence area with M?≥7.0 has been formed in the middle of the North-South seismic zone since 1988, and the Wenchuan earthquake occurred just within this area. There are a background seismicity gap of M?≥5.0 earthquakes and a seismogenic gap of ML?≥4.0 earthquakes in the area of Longmenshan fault zone and its vicinity prior to the Wenchuan earthquake. The seismic activity obviously strengthened and a doughnut-shape pattern of M?≥4.6 earthquakes is formed in the middle and southern part of the North-South seismic zone after the 2003 Dayao, Yunnan, earthquake. Sichuan and its vicinity in the middle of the doughnut-shape pattern show abnormal quiescence. At the same time, the seismicity of earthquake swarms is significant and shows heterogeneity in the temporal and spatial process. A swarm gap appears in the M4.6 seismically quiet area, and the Wenchuan earthquake occurred just on the margin of the gap. In addition, in the short term before the Wenchuan earthquake, the quiescence of earthquake with ML≥?4.0 appears in Qinghai-Tibet block and a seismic belt of ML?≥3.0 earthquakes, with NW striking and oblique with Longmenshan fault zone, is formed. 相似文献
10.
Pei-Yan Chen 《地震学报(英文版)》1997,10(2):181-191
In this paper, the relation that the curves of nonlinear parameter H and its difference ΔH bear with strong earthquakes in North China has been studied. First, the RSH algorithm has been applied to the North China
region; the schemes of six quantitative prediction indexes have been studied in detail and then tested by tracing-back predictions.
The result shows that all the six prediction schemes are of certain prediction efficiency and have passed the test. Among
the six schemes, A and E are of the best effect, with correlation coefficients R of 0.47 and 0.48 respectively. We recommend these two schemes for practical use in prediction in the future. Furthermore,
the relation between the curve of ΔH (the difference of H) and strong earthquake has been studied. Based on the above results, the RSΔH algorithm that uses the
ΔH value to predict strong earthquake has been put forward and applied to predict strong earthquakes in North China. The correlation
coefficient R of tracing-back prediction by this method is 0.45; this means that this method is also of better prediction efficiency. A
combined application of these two algorithms has also been proposed. By the combined method, the time length spanned by false
predictions can be shortened and thus the R value can be raised.
Contribution No. 96A0033, Institute of Geophysics, SSB, China.
This project sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
11.
Experimental dispersion curves of Rayleigh and Love waves along the Uppsala-Prague profile have been determined using records of several Italian earthquakes. To interpret the dispersion data, results of previous geophysical investigations in this region were first analyzed. Seven blocks of the crust and upper mantle were distinguished along the profile on the basis of deep seismic sounding and other seismic data. Layered models were proposed for these blocks. Computation of Rayleigh and Love waves shows a large differentiation of theoretical dispersion curves for the northern (Precambrian) and southern (Palaeozoic) part of the profile. A laterally inhomogeneous model for theUppsala - Prague profile, composed of the seven blocks, satisfies the surface wave data for the profile. Moreover, a mean layered model for the whole profile has also been proposed. 相似文献
12.
The complexity feature of crust-mantle boundary in Zhangbei seismic region and its tectonic implication 总被引：1，自引：0，他引：1
The ProP waveform data obtained from a deep seismic sounding profile, which ran through Zhangbei seismic region, were processed by means of both seismic wave complexity coefficient and frequency spectrum analysis methods, and the complexity characteristics of crest-mantle boundary beneath the studied area and its adjacent region were determined. The results show that the place below epicenter can be taken as boundary, the northern side of which is Inner Mongolia axis with small complexity coefficient and the southern side of which is Huai＇an basin with large complexity coefficient. The different spectrum patterns at the two sides of the epicenter were inferred from spectrum analysis. In the epicentral area, there have been multi-period magmatic eruptions since Meso-Cenozoic and craters exist at the surface. From the velocity imaging of middle and upper crust in Zhangbei seismic region it can be found that there are crustal low velocity bodies around the craters and also there are low velocity zones, which went into deep crust. It is suggested that the distinct zones of crust-mantle boundary complexity may be the margin, where the magma had intruded due to magma activity in Meso-Cenozoic. The southern side with large complexity coefficient is deep magmatic activity area and the northern side with small complexity coefficient is stable crust-mantle tectonics. The difference of crust-mantle complexity provides deep background for the development of strong earthquake. 相似文献
13.
划分大陆活动地块的重要标志之一是它们在地壳结构间的差异。大陆不同地块具有不同的地壳结构特征。这些结构和构造上的不同反映了它们在地壳内部的变形特征和动力过程的差异。文中利用深地震宽角反射 /折射剖面的结果 ,讨论了青藏高原东北缘东昆仑巴颜喀拉地块、鄂尔多斯地块和华北地块唐山震区地壳结构的差异。它们分别是变形强烈的活动地块、内部变形小相对稳定的地块和现代发生过强震的活动地块。在地壳结构上它们之间的差别是明显的。这些差异表现在地壳的分层性质、上地壳和下地壳的结构、地壳结构的不均匀尺度、壳 /幔分界的性质、壳内低速层的分布、地壳界面、特别是莫霍面的构造形态等方面 相似文献
14.
应用灰色系统理论的关联分析方法研究了广西地震活动与我国主要地震区（带）地震活动的相关性．结果表明广西地震活动与东南沿海地震带地震活动的关联程度最大（ｒ＝０．８６）,根据这一结果,对广西与东南沿海地震带的地震活动的相关性作了进一步探讨,发现本世纪以来广西地震活动与东南沿海地震带的地震活动同步起伏,两区（带）之间发生中强地震的互相对应关系特别明显． 相似文献
15.
利用大容量气枪震源在陆上水库进行地震波激发试验,研究陆上水库环境下激发气枪震源所产生的地震波特征及传播距离. 试验结果表明,大容量气枪震源是具有丰富的10 Hz以下低频信号的低频震源,其激发的地震波具有传播距离远,穿透深度深的特点. 在185 km长的测线上均记录到了气枪信号,成功检测到Pg,Pc,P2,PmP和Pn等多组震相,并在此基础上对地下深地壳结构进行了一维速度结构正演,讨论了该区域壳幔过渡带的低速结构. 气枪震源还具有一般炸药震源不具有的特征,如长期定点重复激发和有效转换S波的优点,是陆上进行长炮检距深穿透地下结构研究的一种优良人工震源. 相似文献
16.
According to geological tectonics and seismic activites this paper devided North China (30°–45°N, 105°–130°E) into four areas.
We analyzed the North China earthquake catalogue from 1970 to 1986 (from 1965 to 1986 for Huabei, the North China, plain region)
and identified forty-two bursts of aftershock. Seven of them occurred in aftershock regions of strong earthquakes and seventeen
of them in the seismic swarm regions. The relation between strong earthquakes with the remaining eighteen bursts of aftershocks
has been studied and tested statistically in this paper. The result of statistical testing show that the random probabilityp of coincidence of bursts of aftershock with subsequent strong earthquakes is less than six percent. By Xu’sR scoring method the efficacy of predicting strong earthquake from bursts of aftershock is estimated greater than 39 percent.
Following the method proposed in the paper we analyzed the earthquake catalogue of China from 1987 to June, 1988. The results
show that there was only one burst of aftershock occurred on Jan. 6, 1988 withM=3.6 in Xiuyan of Northeast China. It implicates that a potential earthquake withM
S⩽5 might occur in one year afterwards in the region of Northeast China. Actually on Feb. 25, 1988 an earthquake withM
S=5.3 occurred in Zhangwu of Northeast China. Another example is Datong-Yanggao shock on October 18, 1989 which is a burst
of aftershock. Three hours after an expected shock withM =6.1 took place in the same area. Two examples above have been tested in practical prediction and this shows that bursts
of aftershocks are significant in predicting strong earthquakes.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 273–280, 1991.
Part of earthquake catalogue is from Jinbiao Chen, Peiyan Chen and Quanlin Li. 相似文献
17.
IntroductionMaximumentropyspectralmethod(MEM)(Burg,1972)hadbeenamethodusuallyusedinstudyingtheseismicityanditsmainpurposeistofindthedominantspectrainthelong-termseismicityprocessesinthepastyears(Zhu,1985).Inthispaper,themethodisappliedtostudywhethertherearesomespecialspectraofseismicityinsomespecificstagesinearthquake-generatingprocesses.Sowestudyseparatelythenormalandabnormalstageofearthquakeactivity,whoseactiveprocessisregardedasstablestochasticprocess,inordertofindtheirspectracharactersan… 相似文献
18.
The N2 method for simplified non‐linear seismic analysis has been extended in order to make it applicable to infilled reinforced concrete frames. Compared to the simple basic variant of the N2 method, two important differences apply. A multi‐linear idealization of the pushover curve, which takes into account the strength degradation which occurs after the infill fails, has to be made, and specific reduction factors, developed in a companion paper, have to be used for the determination of inelastic spectra. It is shown that the N2 method can also be used for the determination of approximate summarized IDA curves. The proposed method was applied to two test buildings. The results were compared with the results obtained by non‐linear dynamic analyses for three sets of ground motions, and a reasonable accuracy was demonstrated. A similar extension of the N2 method can be made to any structural system, provided that an appropriate specific R–µ–T relation is available. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
19.
20.
Based on Generalized Seismic Ray Theory (Helmberger, 1968), a new quickly linear inversion method from the data of seismic
waveform to seismic moment tensor and source mechanism for domestic earthquake is studied in this paper. Six moderately strong
earthquakes which occurred in Chinese mainland in the past few years are studied. The seismic source parameters of these earthquakes,
seismic moment tensors, scalar seismic moments, fault plane solutions and source time functionsetc, are obtained.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 261–268, 1993. 相似文献