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401.
The results of Zayü-Qingshuihe MT sounding profile carried out in eastern Tibetan Plateau are presented in this paper. Using 2-D RRI method, the resistivity distribution with depth is obtained along the profile. It is featured by the resistivity zones in the horizontal direction and layers in the vertical direction. The Bangong-Nujiang suture zone and Jinshajiang suture zone are both important electrical conductivity-separating zones in the plateau, and the former is a zone with relatively low resistivity while the latter is an electrical conductivity gradient zone. The highly electrical conductive bodies in the mid and lower crust of northern Qiangtang and Bayan Har Terrain might be caused by regional melting due to shear heating during the process of subduction in tectonic evolution. 相似文献
402.
Common variogram models, such as spherical or exponential functions, increase monotonically with increasing lag distance. On the other hand, a hole-effect variogram typically exhibits sinusoidal waves that form peaks and troughs, thereby conveying the cyclicity of the underlying phenomenon. In order to incorporate this cyclicity into a stochastic simulation, hole effects in the experimental variogram must be fitted appropriately. In this paper, we recommend use of several multiplicative-composite variogram models to fit hole-effect experimental variograms. These consist of a cosine function to provide wavelength and phase of cyclicity, multiplied by a monotonic model (e.g., spherical) to attenuate amplitudes of the cyclical peaks and troughs. These composite models can successfully fit experimental lithology-indicator variograms that contain a range of cyclicities, although experimental variograms with poor cyclicity require special considerations. 相似文献
403.
干旱、半干旱区域降水趋势可预报期限的初步研究 总被引:1,自引:0,他引:1
应用中国西北和美洲大陆中部干旱、半干旱区域7个长记录站的月降水量记录,分析了降水趋势的可预报期限问题。结果表明:月降水量标准化系数序列的可预报尺度为3个月左右。将该序列进行差分运算后,误差倍增时间会显著加长。 相似文献
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406.
Hu Yuliang Liu Zuyuan Yang Oingyuan Chen Xiancheng Hu Ping Ma Wentao Lei Jun 《Pure and Applied Geophysics》1996,147(2):409-418
To date 19 cases of reservoir-induced seismicity have been acknowledged in China and 15 of them are associated with karst. The Wujiangdu case is a typical one induced in the karst area. The dam with a height of 165 m is the highest built in a karst area in China. Seismic activity has been successively induced in five reservoir segments seven months after the impoundment in 1979. A temporary seismic network consisting of 8 stations was set up in one of the segments some 40 km upstream from the dam. The results indicate that epicenters were distributed along the immediate banks, composed of karstified carbonate, and focal depths were only several hundred meters. Most of the focal mechanisms were of thrust and normal faulting. It is suggested that karst may be an important factor in inducing seismicity. It can provide an hydraulic connection to change the saturation and pressure and also weak planes for dislocation to induce seismicity. 相似文献
407.
A complete yearly record (1988) of surface measurements is used to examine the atmospheric diurnal secondary circulations over the entire area of Hong Kong in conjunction with spatial and temporal variations of surface temperature, wind speed and rainfall. Evidence of atmospheric diurnal secondary circulations is found at 10 sites. The occurrence of a summer morning rainfall maximum over the coast results from the interaction of the large-scale summer monsoon and local mesoscale secondary circulations. The afternoon onshore secondary circulation accelerates the advection of warm, humid unstable air and, coupled with the upward orographic lifting, produces enhanced rainfall along windward mountain ridges.Dynamical and scaling considerations suggest that the blocking effect is negligible and the primary forcing mechanism is land-sea temperature difference, but terrain effects are also important. Although the secondary circulation system's strength and timing vary, the circulation behaves like a classic sea-land breeze circulation, complicated by superimposed mountain-valley breezes. 相似文献
408.
1993年5月4~6日在我国西北部地区发生了一次“黑风暴”。用改进的MM1和高分辨PBL参数化及40 km细网格控制试验能基本上模拟出“93.5”黑风暴的结构和演变。模拟结果表明,黑风暴发展时段,在PBL内与一个中尺度气旋性强涡旋相伴,在对流层内与一个垂直涡柱相伴。这个伸展至对流层顶的涡柱下(上)半部是与低(高)空强烈辐合(辐散)入(外)流相伴的气旋(反气旋)性涡柱。该黑风暴结构不同于一般锋面结构,其主要判别是:界面坡度陡,θe水平梯度大,斜压性强,PBL内暖心明显。该暖心结构与下垫面剧烈热力强迫有关。不 相似文献
409.
410.
长白山天池火山地震类型与地震分布 总被引:13,自引:2,他引:13
根据1985 ̄1995年天池火山地震观测,对天池火山地震类型及地震分布进行了讨论,并对天池火山地震的波形特征作了分析,最后,对天池火山地震与监测提出了3点建议。 相似文献