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751.
Yu Haiying 《中国地震研究》2007,21(1):55-61
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
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Eugene Yee Ralph M. Gailis Alexander Hill Trevor Hilderman Darwin Kiel 《Boundary-Layer Meteorology》2006,121(3):389-432
We report on measurements of the near-field dispersion of contaminant plumes in a large array of building-like obstacles at three scales; namely, at full-scale in a field experiment, at 1:50 scale in a wind-tunnel simulation, and at 1:205 scale in a water-channel simulation. Plume concentration statistics extracted from the physical modelling in the wind-tunnel and water-channel simulations are compared to those obtained from a field experiment. The modification of the detailed structure of the plume as it interacts with the obstacles is investigated. To this purpose, measurements of the evolution of the mean concentration, concentration fluctuation intensity, concentration probability density function, and integral time scale of concentration fluctuations in the array plume obtained from the field experiment and the scaled wind-tunnel and water-channel experiments are reported and compared, as well as measurements of upwind and within-array velocity spectra. Generally, the wind-tunnel and water-channel results on the modification of the detailed plume structure by the obstacles were qualitatively similar to those observed in the field experiments. However, with the appropriate scaling, the water-channel simulations were able to reproduce quantitatively the results of the full-scale field experiments better than the wind-tunnel simulations. 相似文献
755.
信号相关性方法在西藏那曲台阵设计中的应用 总被引:6,自引:2,他引:6
作者对2004年8月在那曲地区勘址时所获地震波形数据进行了处理。利用由勘址记录波形中发现测点对之间在时域和频域的相关性,给出了台阵内外环半径的参考值,并把勘址布设的台阵作为初选台阵进行了评估。结果证明初选台阵的分辨率很高,能够做到精确的地震的精定位。 相似文献
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Tadashi Kito Takuo ShibutaniKazuro Hirahara 《Physics of the Earth and Planetary Interiors》2003,138(1):55-69
Precursor and coda portions of short-period PcP waves (reflected P wave from the core-mantle boundary, CMB) recorded at J-array stations in Japan were analyzed in order to extract weak scattered signals originating from small-scale heterogeneities in the lowermost mantle beneath northeastern China. Two nuclear explosions at Lop Nor in China detonated on 21 May 1992 (Mb=6.5) and 8 June 1996 (Mb=5.9) were used for our analysis.Three-dimensional grids above the CMB were defined in the area around the PcP bounce points beneath northeastern China to calculate theoretical travel times of scattered waves which propagate from the sources to each grid point and arrive at each station based on the IASP91 model. Subsequently the waveforms were aligned with respect to the theoretical travel times and the semblance (an amplitude dependent measure of coherency) was calculated for each grid point. In order to obtain a more accurate travel time correction, we applied a cross correlation method to PcP waveforms in order to reduce picking error of the PcP onset time. A cross convolution method was also applied so that the two events could be analyzed simultaneously without using unstable deconvolutions.We could identify regions with relative high semblance values in semblance contour maps at about 200 and 375 km above the CMB. Stacking waveforms with respect to the theoretical travel times for the grid points with relative high semblance values indicate coherent wavelets originating at those grid points, that is, they correspond to scattered waves originating from small-scale heterogeneities in the lowermost mantle. Our results indicate the existence of small-scale scattering objects in the D″ layer, especially in the depth range of 200 and 375 km above the CMB beneath northeastern China. Considering recent tomographic images of high velocity anomalies in this area, these scattering objects could be fragments of old oceanic crusts which have subducted through the lower mantle and have accumulated in the D″ layer beneath northeastern China. 相似文献
758.
三维地震勘探固定排列与中点放炮观测系统 总被引:1,自引:0,他引:1
三维地震勘探观测系统的模式较多,以常规束状观测系统的应用较为广泛。针对勘探区目的任务选择合理的观测系统以有利于勘探效果,是勘探前期施工设计的基本要求。三维地震勘探固定排列与中点放炮两种新型观测系统,均可使炮点在勘探区内呈地段性分布,与常规束状观测系统炮点在勘探区呈分散分布有所不同。在满足多次叠加提高分辨率的同时,能够使施工排列的滚动次数明显减少,从而使野外数据采集工作效率得以有效提高,并降低了生产成本,扩充了施工设计选择观测系统的范围,在三维地震勘探行业具有一定的实用价值。 相似文献
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全时域时间谱视电阻率算法研究 总被引:4,自引:0,他引:4
本文采用数值逼近的方法,逐段用多项式表示偶极—偶极排列的瞬变电场。根据求出的多项式指数和系数,建立全时域时间谱视电阻率的算法。该算法能对小收发距(r与h1相近或更小)时的瞬变电场,计算出可形象反映地电断面的视电阻率。 相似文献