根据构造环境剪应力值水平区分地震和核爆炸   总被引：5，自引：1，他引：5       下载免费PDF全文

陈培善  成瑾  白彤霞 《地震学报》2001,23(3):246-249

根据地震破裂的断裂力学模式，导出了震源参数与地震发生处的构造环境剪应力值t0之间的函数关系．据此，可以大量计算震源处的构造环境剪应力值或背景应力值．若把核爆炸当作地震来计算，发现核爆炸的t0值平均在20MPa左右，明显地高于同震级地震的t0值．其结果可以作为区分地震与核爆炸的依据．   相似文献   

强震成组活动与潮汐力调制触发   总被引：14，自引：4，他引：14  

张国民  李丽  黎凯武  马宏生 《中国地震》2001,17(2):110-120

本文应用构造场体成组震模型的研究结果，探讨了中国大陆Ms≥7．0地震的成组活动的引潮力的调制触发关系。研究表明：我国陆区7级以上强震明显受潮汐力的调制触发，且主要表现为对活跃期内（即成组发生的）7级强震的调制触发。平静期内的7级以上地震基本不受潮汐力触发，而活跃期内82．4％的7级强震发生在受潮汐力触发的月相期，比本底概率高出36．4％。因此，潮汐力的调制触发对于强震活跃期的判断和活跃期内强震的临震（时间）预测有实际意义。文章还分析了潮汐力触发与强震活动的区域动力学环境之间的关系，并用构造场体成组孕震模型讨论了潮汐力对强震活动触发作用的力学机制。  相似文献   

Discrimination between nuclear explosions and earthquakes based on consideration of tectonic ambient shear stress values     

陈培善  成瑾  白彤霞 《地震学报(英文版)》2001,14(3):259-262

IntroductionFor the need of a nuclear test ban treaty, international society must make great efforts to find effective methods for discrimination between earthquake and nuclear explosion. Thereupon, many methods of discrimination of nuclear explosion appeared. But, at present, there is some uncertainty to discriminate middle or small nuclear explosion (Peppin, McEvilly, 1974; Richards, Zarales, 1990). When we study tectonic ambient shear stress field of Southern California, we find that str…  相似文献   

A new model on the cause of Tangshan earthquakes in 1976     

王健 《地震学报(英文版)》2001,14(5):589-595

Introduction The Tangshan earthquake sequence in 1976 is one of most important events in North China. Although nearly thirty years passed and there are some researches on its cause, it is far from the end. Here we introduce two explanations for the cause of Tangshan earthquakes and point out their defects. One is that there is a diamond block in NEE direction in Tangshan region, which is shaped by cutting action of NingheChangli fault, FengtaiYejituo fault, Luanxian fault and Jiyunhe fau…  相似文献   

Seismicity, seismotectonics and crustal structure of the southern Kenya Rift—new data from the Lake Magadi area     

M. Ibs-von Seht  S. Blumenstein  R. Wagner  D. Hollnack  J. Wohlenberg 《Geophysical Journal International》2001,146(2):439-453

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Study on the relationship between geothermal exploitation and seismic activity in Xi’an region     

Wu Fu-chun  Song Li-sheng  Zhu Xing-guo  Wang Feng  Jing Bei-ke  Dong Xing-hong  Fang Wei  Zuo Yong-qing 《地震学报(英文版)》2001,14(4):434-439

Based on the analysis of the induced earthquakes in China and abroad, we get some ideas about earthquakes induced by pumping water out of a well or injecting water into a well. The induced earthquakes usually occur near the well, and they are generally small earthquakes. The earthquake sources are shallow, and they belong to the main shock-after shock type of earthquake or the swarm-type of earthquake. The magnitude and the quantity of the induced earthquakes obviously depend on the pressure and the quantity of water pumped or injected. These earthquakes happen as soon as pumping or injecting occurrence, or after ten or twenty days, they may occur at the time of injecting mud or injecting high pressure water when a well is being drilled, or at the time when the ground water is being normally exploited. A large quantity of hot water has been exploited since 1990 in Xi’an, and the quantity of water exploited has been increasing year by year, as a result the groundwater level has been dropping with the water pumped out and the water level is high in summer and low in winter. The earthquakes in Xi’an region belong to the solitary-type and they spread outside Xi’an city where the wells are concentrated but no earthquake happens. The seismic frequency and the energy released have no relation with the quantity of water exploitation or the water level in the well. It is considered that geothermal exploitation does not induce earthquakes in and around Xi’an because of its specially geological condition. Foundation item: Project sponsored by the Landslide Office of Shaanxi Province and Society of Disaster Reduction of Shaanxi Province.  相似文献   

The earthquake sequence of May 1951 at Jucuapa, El Salvador     

N.N. Ambraseys  J.J. Bommer  E. Buforn  A. Udías 《Journal of Seismology》2001,5(1):23-39

Three earthquakes that happened over two days in May 1951 caused extensive damage to villages in a small area of eastern El Salvador (Central America). Contemporary hypocentral solutions indicated focal depths, confirmed by re-calculations using available seismic data, of the order of 90 km, suggesting events associated with the subducted Cocos plate. Macroseismic observations strongly indicate that the earthquakes were of very shallow focus and this is supported by wave-form modeling and the appearance of seismograms recorded in Guatemala. A re-evaluation of the location and source characteristics for these events is presented, together with a fault plane solution and additional macroseismic evidence. The implications for seismic hazard and risk assessment in Central America, where shallow earthquakes of moderate magnitude, frequently occurring in clusters, pose the greatest threat to settlements which, like the area affected by these events, are concentrated along the axis of Quaternary volcanoes.  相似文献   

Group Strong Earthquakes and Triggering by Tidal Stress   总被引：4，自引：1，他引：4  

Zhang Guomin  Li Li  Li Kaiwu  Ma Hongsheng 《中国地震研究》2001,15(4):354-364

The results obtained using the group model of earthquakes generated in tectonic blocks are fur ther used in this paper to analyze the relationship between the Ms ≥ 7.0 events in Chinese ma inland and the modulation and triggering from the earth tides. The research shows that the Ms 7.0 events in Chinese mainland have been significantly triggered by the tidal stress, especially within the active period with group strong earthquakes. In the quiescence period of strong earthquakes, no Ms7.0 events were triggered, while within the active period, over 82.4% of strong earthquakes took place within a special moon phase, which is 36.4 % higher than the average. Therefore, the modulation and triggering of tidal stress can be used to distinguish the active periods and to forecast the time of the strong earthquakes within the active period. The relationship between the tidal triggering and the tectonic dynamic condition is investigated and the mechanism of the modulation is simulated with the group model of earthquakes generated in tectonic blocks.  相似文献   

Inelastic buildings with tuned mass dampers under moderate ground motions from distant earthquakes     

P. Lukkunaprasit  A. Wanitkorkul 《地震工程与结构动力学》2001,30(4):537-551

The effectiveness of tuned mass dampers (TMD) in vibration control of buildings was investigated under moderate ground shaking caused by long‐distance earthquakes with frequency contents resembling the 1985 Mexico City (SCT) or the 1995 Bangkok ground motion. The elastic–perfectly plastic material behaviour was assumed for the main structure, with linear TMDs employed by virtue of their simplicity and robustness. The accumulated hysteretic energy dissipation affected by TMD was examined, and the ratio of the hysteretic energy absorption in the structure with TMD to that without it is proposed to be used, in conjunction with the peak displacement ratio, as a supplementary TMD performance index since it gives an indication of the accumulated damage induced in the inelastic structures. For the ground motions considered, TMD would be effective in reducing the hysteretic energy absorption demand in the critical storeys for buildings in the 1.8–2.8 s range. The consequence is reduction in damage of the buildings which would otherwise suffer heavy damage in the absence of TMD, resulting in economical restorability in the damage control limit state. This is of practical significance in view of the current trend toward performance‐based design. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Pounding of structures modelled as non‐linear impacts of two oscillators     

K. T. Chau  X. X. Wei 《地震工程与结构动力学》2001,30(5):633-651

A new formulation is proposed to model pounding between two adjacent structures, with natural periods T₁ and T₂ and damping ratios ζ₁ and ζ₂ under harmonic earthquake excitation, as non‐linear Hertzian impact between two single‐degree‐of‐freedom oscillators. For the case of rigid impacts, a special case of our analytical solution has been given by Davis (‘Pounding of buildings modelled by an impact oscillator’ Earthquake Engineering and Structural Dynamics, 1992; 21 :253–274) for an oscillator pounding on a stationary barrier. Our analytical predictions for rigid impacts agree qualitatively with our numerical simulations for non‐rigid impacts. When the difference in natural periods between the two oscillators increases, the impact velocity also increases drastically. The impact velocity spectrum is, however, relatively insensitive to the standoff distance. The maximum relative impact velocity of the coupled system can occur at an excitation period T_n^* which is either between those of the two oscillators or less than both of them, depending on the ratios T₁/T₂ and ζ₁/ζ₂. Although the pounding force between two oscillators has been primarily modelled by the Hertz contact law, parametric studies show that the maximum relative impact velocity is not very sensitive to changes in the contact parameters. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献