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101.
102.
利用上海台阵对常熟2001年2002年震群的精定位 总被引:1,自引:0,他引:1
2001年6月上海台阵正式运行,上海台阵的建立提高了上海及周边地区的地震监测能力.本文着重在定位方法和震相判读上,充分利用上海台阵整体观测系统的优势和台阵独特的数据处理方法,对常熟2001年和2002年二次小地震序列进行了精确定位.对精确定位的结果进行了对比与分析,并以此为基础,对常熟地区及周边的地质构造等进行了解释与推断. 相似文献
103.
H. Kit Miyamoto Amir S. J. Gilani Akira Wada Christopher Ariyaratana 《地震工程与结构动力学》2010,39(11):1279-1297
Fluid viscous dampers are used to control story drifts and member forces in structures during earthquake events. These elements provide satisfactory performance at the design‐level or maximum considered earthquake. However, buildings using fluid viscous dampers have not been subjected to very large earthquakes with intensities greater than the design and maximum considered events. Furthermore, an extensive database of viscous damper performance during large seismic events does not exist. To address these issues, a comprehensive analytical and experimental investigation was conducted to determine the performance of damped structures subjected to large earthquakes. A critical component of this research was the development and verification of a detailed viscous damper mathematical model that incorporates limit states. The development of this model and the laboratory and simulation results conclude good correlation with the new model and the damper limit states and provide superior results compared with the typical damper model when considering near collapse evaluation of structures. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
104.
Emile A. Okal 《Natural Hazards》1988,1(1):67-96
We present a review of the influence of various parameters of the sources of major oceanic earthquakes on the amplitude of tsunamis at transoceanic distances. We base our computations on the normal mode formalism, applied to realistic Earth models, but interpret our principal results in the simpler framework of Haskell theory in the case of a water layer over a Poisson half-space. Our results show that source depth and focal geometry play only a limited role in controlling the amplitude of the tsunami; their combined influence reaches at most 1 order of magnitude down to a depth of 150 km into the hard rock. More important are the effects of directivity due to rupture propagation along the fault, which for large earthquakes can result in a ten-fold decrease in tsunami amplitude by destructive interference, and the possibility of enhanced tsunami excitation in material with weaker elastic properties, such as sedimentary layers. Modelling of the so-called tsunami earthquakes suggests that an event for which 10% of the moment release takes place in sediments generates a tsunami 10 times larger than its seismic moment would suggest. We also investigate the properties of non-double couple sources and find that their relative excitation of tsunamis and Rayleigh waves is in general comparable to that of regular seismic sources. In particular, landslides involving weak sediments could result in very large tsunamis. Finally, we emphasize that the final amplitude at a receiving shore can be strongly affected by focusing and defocusing effects, due to variations in bathymetry along the path of the tsunami. 相似文献
105.
N. Segovia S. de la Cruz-Reyna M. Mena E. Ramos M. Monnin J. L. Seidel 《Natural Hazards》1989,1(4):319-329
A radon anomaly in a nuclear track detector placed on a fault was detected prior to the destructive (Ms = 8.1) Mexican earthquake of 19 September 1985. The fault is a structural feature of the geothermal field Los Azufres, 260 km NE of the epicentral area. Since no other phenomenon can be found as a possible cause for the radon anomaly, it is proposed that preseismic regional stress perturbations may produce changes in the fluid transport patterns at the fault, suggesting that radon measurements in similar conditions could provide a good precursor in high seismic risk areas. 相似文献
106.
James F Ni 《Journal of Earth System Science》1989,98(1):71-89
The Himalayan mountains are a product of the collision between India and Eurasia which began in the Eocene. In the early stage
of continental collision the development of a suture zone between two colliding plates took place. The continued convergence
is accommodated along the suture zone and in the back-arc region. Further convergence results in intracrustal megathrust within
the leading edge of the advancing Indian plate. In the Himalaya this stage is characterized by the intense uplift of the High
Himalaya, the development of the Tibetan Plateau and the breaking-up of the central and eastern Asian continent. Although
numerous models for the evolution of the Himalaya have been proposed, the available geological and geophysical data are consistent
with an underthrusting model in which the Indian continental lithosphere underthrusts beneath the Himalaya and southern Tibet.
Reflection profiles across the entire Himalaya and Tibet are needed to prove the existence of such underthrusting. Geodetic
surveys across the High Himalaya are needed to determine the present state of the MCT as well as the rate of uplift and shortening
within the Himalaya. Paleoseismicity studies are necessary to resolve the temporal and spatial patterns of major earthquake
faulting along the segmented Himalayan mountains. 相似文献
107.
一、前言 中纬度地区电离层Es的成因与影响因素是一复杂的问题。远东地区Es既多又强,其它电离层现象也有一些特色,本文在文献[9]的基础上,从分析原始频高图入手,对远东地区夜间f0Es剧增与地磁K指数的关系作了统计研究,发现两者之间关系甚为密切,即地磁K指数的突然变化伴随着夜间Es层临界频率f0Es的剧烈增加。 相似文献
108.
Bruce S. Gibson 《Pure and Applied Geophysics》1988,128(1-2):309-331
Three types of seismic data recorded near Coalinga, California were analyzed to study the behavior of scattered waves: 1) aftershocks of the May 2, 1983 earthquake, recorded on verticalcomponent seismometers deployed by the USGS; 2) regional refraction profiles using large explosive sources recorded on essentially the same arrays above; 3) three common-midpoint (CMP) reflection surveys recorded with vibrator sources over the same area. Records from each data set were bandpassed filtered into 5 Hz wide passbands (over the range of 1–25 Hz), corrected for geometric spreading, and fit with an exponential model of amplitude decay. Decay rates were expressed in terms of inverse codaQ (Q
c
–1
).Q
c
–1
values for earthquake and refraction data are generally comparable and show a slight decrease with increasing frequency. Decay rates for different source types recorded on proximate receivers show similar results, with one notable exception. One set of aftershocks shows an increase ofQ
c
–1
with frequency.Where the amplitude decay rates of surface and buried sources are similar, the coda decay results are consistent with other studies suggesting the importance of upper crustal scattering in the formation of coda. Differences in the variation ofQ
c
–1
with frequency can be correlated with differences in geologic structure near the source region, as revealed by CMP-stacked reflection data. A more detailed assessment of effects such as the depth dependence of scattered contributions to the coda and the role of intrinsic attenuation requires precise control of source-receiver field geometry and the study of synthetic seismic data calculated for velocity models developed from CMP reflection data. 相似文献
109.
A. M. Shurygin 《Mathematical Geology》1993,25(7):759-772
The model of the Poisson point process is too vague for earthquake locations in space and time: earthquakes tend to cluster in middle distances and to repulse in large ones. The Poisson point model with variable density makes it possible to describe the tendency for clustering but does not reveal the periodicity of clusters. The author proposes the point-process model where locations of points are determined not by densities of point distribution, but by densities of interpoint differences distribution. In the model, a latent periodicity is revealed and used for prediction of a point process. In 1983, the point-process model prediction was made for the Kuril Islands for 1983–1987 and two signs of danger in time and location were determined. Then they were confirmed by strong earth-quakes. In 1989, a similar prediction was made for North Armenia. The Spitak earthquake in 1988 is clearly seen from the data of previous earthquakes. 相似文献
110.