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1.
Introduction With rapid development of national economy, urbanization has been speeded up in China, and several city groups or city belts with extra-large cities as their centers have been formed. For example, Pearl River Delta urbanized area surrounds Guangzhou City, Shenzhen City, Zhuhai City; Yangtze River Delta urbanized area surrounds Shanghai City, Suzhou City, Wuxi City, Nanjing City, Hangzhou City; Beijing-Tianjin-Tangshan urbanized area surrounds Beijing City, Tianjin City…  相似文献   

2.
INTRODUCTIONThe active blocks refer tothe geologic units that formedinlate Cenozoic (100 ~120 ka BP) andhave been highly active as fault zones since late Quaternary with relatively uniform motion styles(Zhang Guomin,et al .,2000 ;Zhang Peizhen,et al .,2003) .The active blocks are relativelyintactand have uniformmotion modalities ,their boundary zones (also called the active boundaries) are thelocalized or centralized zones of interactions and differential movement among the active block…  相似文献   

3.
On the basis of distribution of active fault and regional rheological structure, a three-dimensional finite element model of Sichuan-Yunnan region, China, is constructed to simulate contemporary crustal motion and stress distri- bution and discuss the dynamic mechanism of crustal motion and deformation in the Sichuan-Yunnan region. Lin- ear Maxwell visco-elastic model is applied, which includes the active fault zones, the elastic upper crust and vis- cous lower crust and upper mantle. Four different models with different boundary conditions and deep structure are calculated. Some conclusions are drawn through comparison. Firstly, the crustal rotation about the eastern syntaxis of the Himalaya in the Sicuan-Yunnan region may be controlled by the special dynamic boundary condition. The drag force of the lower-crust on the upper crust is not negligible. At the same time, the main active fault zones play an important role in the contemporary crustal motion and deformation in Sichuan-Yunnan region.  相似文献   

4.
Introduction With rapid development and advancement of economy and society, lots of city groups or city belts with ex-tra-large cities as their centers have been formed in China. The regions these city groups lie in usually have well-developed economy, dense population, and are regional politics and culture centers. Some groups lie in the regions with high level of earthquake activity, such as the Surrounding Capital City Group with the centers of Bei-jing and Tianjin. Once a large earthqua…  相似文献   

5.
Earth temperature is one of the most important factors influencing the mechanical properties of frozen soil. Based on the field investigation of the characteristics of ground deformation and ground failure caused by the Ms8.1 earthquake in the west of the Kuniun Mountain Pass,China, the influence of temperature on the dynamic constitutive relationship, dynamic elastic modulus, damping ratio and dynamic strength of frozen soil was quantitatively studied by means of the dynamic triaxial test. Moreover, the characteristics of ground motion on a permafrost site under different temperatures were analyzed for the four profiles of permafrost along the Qinghai-Xizang (Tibet) Railway using the time histories of ground motionacceleration with 3 exceedance probabilities of the Kunlun Mountains area. The influences of temperature on the seismic displacement, velocity, acceleration and response spectrum on permafrost ground were studied quantitatively. A scientific basis was presented for earthquake disaster mitigation for engineering foundations, highways and underground engineering in permafrost areas.  相似文献   

6.
The paper proposes the calibration theory and methods for the Shanghai seismic array and analyzes the calibration results. As a result, the calibration results for the seismic array based on 2 typical earthquakes have been drawn; the difference of calibration results between Hokkaido and Honshu region in Japan is investigated. And calibration results of different directions, different epicenter distances and different magnitudes are probed into. The result shows that the location of earthquakes on the Shanghai seismic array is greatly improved.  相似文献   

7.
Data on variations in the content of the 14C cosmogenic isotope in tree rings and the Earth’s atmosphere (Δ14C) make it possible to study the behavior of solar activity (SA) in previous centuries and millenniums. The latter is related to the fact that SA temporal variations result in a change in the IMF (Interplanetary Magnetic Field) parameters and, as a consequence, in the galactic cosmic ray (GCR) flux, under the action of which the 14C isotope is produced in the Earth’s atmosphere. This makes it possible to study SA history based on data on the 14C isotope content in tree rings. However, in this case we have several difficulties related to climate change. Climate changes result in carbon redistribution between natural reservoirs, which is reflected in radiocarbon data and results in solar signal distortion. The effect of variations in the global temperature and carbon dioxide concentration on the reconstruction of the heliospheric modulation potential and Wolf numbers from the late 14th century to the early 19th century is considered. It has been shown that the radiocarbon data do not make it possible to conclude that SA during the Maunder minimum was extremely low as compared to SA during the Dalton minimum.  相似文献   

8.
The opinions of two papers carried in the journal "Seismology and Geology" are discussed in the paper.One is that the Tangshan fault is a high-angle,west-dipping and thrust with strike-slip fault.The other is that the Fuzhuang-Xihe fault distributed on the east side of Tangshan city is the seismogenic fault that caused the Tangshan earthquake.For the former opinion,it needs to explain the relationship between the active style of the thrust Tangshan fault and the formation genesis of a Quaternary depression along the west side of Tangshan city.For the latter opinion,if the Fuzhuang-Xihe fault is the seismogenic fault of the Tangshan earthquake,it needs to explain the genesis relationship between this west-dip slip fault zone and the strike-slip surface fissure zone that extends through Tangshan city.And it needs more evidence exclude the possibility that the surface rupture belongs to the rupturing of a secondary structure.This paper suggests doing more work on the active fault that controls the Caobo Quaternary depression.  相似文献   

9.
INTRODUCTIONAn earthquake ofML5·0 occurredin Barkamcounty,Aba Prefecture ,Sichuan Province onJan.1 ,2005 ,and was located at the northwest of the Songganfault ,an area betweenthe Songgangfault ,Yukefault , Darlag fault and Madoi-Gad毢fault . TheML5·0 earthquake is the biggest one in AbaPrefecture since theM6·6 Xiaojinearthquake of 1989 and alsothe biggest oneinthe area betweentheSonggangfault ,Yuke fault ,Darlagfault and Madoi-Gad毢fault since Nov.8 ,1970·Since the commencem…  相似文献   

10.
Paleo-earthquake studies on the eastern section of the Kunlun fault   总被引：1，自引：0，他引：1  
Introduction East Kunlun active fault is one of the largest sinistral slip fault zones in northern Tibetan Pla-teau. The fault tails primarily after the ancient eastern Kunlun suture zone, which was reactivatedby the northward subduction of the Indian plate beneath the Eurasian plate. The western end of thefault starts near the western flank of the Buxedaban peak in Qinghai Province. The fault then ex-tends eastwards through the Kusai Lake, Xidatan, Dongdatan, Alag Lake, Tuosuo Lak…  相似文献   

11.
It has been recognized for a long time that the b-value in the Gutenberg-Richters fre-quency-magnitude relation (Gutenberg, Richter, 1954) tends to decrease before some of the earth-quakes (LI, et al, 1979, and the references therein). Since the 1980s, study on b-value has caused much attention among seismologists and physicists when b-value was related to the fractal dimen-sion of an earthquake fault (Aki, 1981; King, 1983) and/or the scaling constant in the model of self-organized critical…  相似文献   

12.
IntroductionQinghai-Xizang(QingzangorTibetan)plateauisthemostremarkableactivecollisionbeltontheEarth.Itsaveragealtitudeis5km,itscrustthicknessupto70kmanditsareaabout7?05km2.Inrecenttwentyyears,withthegeophysicalobservationdatagettingmoreandmore,manydy-namicmodelsaboutcrustthickeningandTibetanuplifthavebeenputforward(Harrison,etal,1992;LI,1995;ZENG,etal,1994;ZHONG,DING,1996;XIAO,WANG,1998).Theycanbedividedintotwotypes.ThefirsttypecharacterizesthattheconvergencebetweenIndiaandEura-s…  相似文献   

13.
1INTRODUCTION TheTianqiaogou Huangyangchuanfault(alsocalledGulangfault)isanimportantpartofanactivefaultzoneontheeasternsectionofthenorthernQilianMountains.Therecentactivityofthefaulthasbeenstudiedtodifferentdegrees(WanFuling,1987;InstituteofGeology,StateS…  相似文献   

14.
The mechanism of the effects of the upwelling mean on the ENSO event mature phase locking is ex-amined by using a mixed-mode model. The results show that the positive feedback process of the ef-fects of the seasonal variation of the upwelling mean on the Kelvin wave is the mechanism of the locking of the event mature phase to the end of the calendar year. The memory of the Rossby waves for the sign-shifting of the sea surface temperature anomaly from positive to negative 6 months before the cold peak time is the other mechanism of the locking of the La Nia event mature phase to the end of the calendar year. The results here are different from previous ones which suggest that the balance between cold and warm trends of sea surface temperature anomaly is the mechanism involved. The cold trend is caused by the upwelling Kelvin wave from upwelling Rossby wave reflected at the western boundary, excited by the westerly anomaly stress over the central Pacific and amplified by the seasonal variation of the coupled strength in its way propagating westward. The warm trend is caused by the Kelvin wave forced by the western wind stress over the middle and eastern equatorial Pacific. The cause of the differences is due to the opposite phase of the seasonal variation of the upwelling mean to that in the observation and an improper parameterization scheme for the effects of the seasonal varia-tion of the upwelling mean on the ENSO cycle in previous studies.  相似文献   

15.
This paper has two main purposes. One is to present and analyse soil and structural vibration data obtained experimentally during certification testing of the high-speed train line between Córdoba and Málaga (Spain) that was opened on December 2007. The second is to show the capabilities of a three-dimensional boundary element method (BEM)/finite element method (FEM) numerical approach for the analysis of train induced vibrations. The model can represent local soil conditions, discontinuities such as underpasses, as well as structures placed next to the rail track. Vibrations in those structures can be computed taking into account, in a rigorous way, dynamic soil–structure interaction and local soil properties. Experimental and numerical results at several points near the track are compared. Results for an overhead contact support structure are also evaluated. The comparison of numerically predicted and recorded results shows that the model is reliable for predicting the amplitude of vibrations produced in the soil and nearby structures by high-speed trains.  相似文献   

16.
The pattern of the subtle traps, in which oil and gas accumulated, in the buried-hill faulted zone in the Jiyang sag is very complicated, and very hard to prospect. The paper analyses the main difficulties in exploring the complicated buried-hill faulted zone of the area from a point of geology.The typical pattern of the buried-hill zone in the Jiyang sag is studied using the forward modeling.Target-orient layout design and full 3-D seismic technology, which are useful for oil and gas exploration on the zone, are put forward. Taking the exploration for oil and gas traps on the zone as an example, certain technologies and the effect of their applications about the design for target acquisition,acquisition on a wide-azimuth, point sources and point receivers are discussed.  相似文献   

17.
Foreland basins on the western edge of Ordos are characterized by typical loess geomorphologic features. Its surface is severely cut, and its underground geological structures are complicated.Making use of the advantage of CEMP in exploration in frontland as well as successful multi-year exploration experiences in West China, we first employed the CEMP method to conduct exploration on the western edge of the Ordos basin and its surrounding areas. The practices proved that rich and reliable geological results have been achieved with the CEMP method in complicated areas covered with loess. This can provide important evidence for researching the contact relationship among basins and mountains, structural feature of target layers and predict favourable areas.  相似文献   

18.
1 Geologic setting and layout of the DSS observation network In the studied area there are three major tectonic units, which are referred to as Tianshan fold system, Tarim basin and West Kunlun fold system (Bureau of Geology and Mineral Resources of Xinjiang Uygur Autonomous Region, 1993). The Tianshan fold system is a polycyclic geosyncline on the north edge of Tarim basin, and an orogenic zone resulting from collision and convergence between Tarim block and the Junggar-North Tianshan…  相似文献   

19.
ＰｒｅｌｉｍｉｎａｒｙｓｔｕｄｙｏｎｔｈｅｄｕｒａｔｉｏｎｏｆｅａｒｔｈｑｕａｋｅａｃｔｉｖｉｔｙＦｕ－ＭｉｎｇＨＵＡＮＧ（黄福明）（ＩｎｓｔｉｔｕｔｅｏｆＣｒｕｓｔａｌＤｙｎａｍｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎ...  相似文献   

20.
Over the past few decades, soil densification has been widely employed to reduce the liquefaction hazard or consequences on structures. The decision to mitigate and the design of densification specifications are typically based on procedures that assume free‐field conditions or experience. As a result, the influence of ground densification on the performance of structures and the key mechanisms of soil‐structure interaction remains poorly understood. This paper presents results of four centrifuge tests to evaluate the performance of 3‐ and 9‐story, potentially inelastic structures on liquefiable ground with and without densification. Densification was shown to generally reduce the net excess pore pressures and foundation permanent settlements (although not necessarily to acceptable levels), while amplifying the accelerations on the foundation. The influence of these demands on the performance of the foundation and superstructure depended on the structure's strength and dynamic properties, as well as ground motion characteristics. In addition, densification tended to amplify the moment demand at the beam and column connections, which increased permanent flexural deformations and P‐Δ effects (particularly on the heavier and weaker structure) that could have an adverse effect on foundation rotation. The experimental results presented aim to provide insight into the potential tradeoffs of ground densification, which may reduce foundation permanent settlement, but amplify shaking intensity that can result in larger foundation rotation, flexural drifts, and damage to the superstructure, if not considered in design. These considerations are important for developing performance‐based strategies to design mitigation techniques that improve performance of the soil‐foundation‐structure system in a holistic manner.  相似文献   

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