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131.
We conducted moment tensor inversion and studied source rupture process for M
S=7.9 earthquake occurred in the border area of China, Russia and Mongolia on September 27 2003, by using digital teleseismic
P-wave seismograms recorded by long-period seismograph stations of the global seismic network. Considering the aftershock
distribution and the tectonic settings around the epicentral area, we propose that the M
S=7.9 earthquake occurred on a fault plane with the strike of 127°, the dip of 79° and the rake of 171°. The rupture process
inversion result of M
S=7.9 earthquake shows that the total rupture duration is about 37 s, the scalar moment tensor is M
0=0.97×1020 N·m. Rupture mainly occurred on the shallow area with 110 km long and 30 km wide, the location in which the rupture initiated
is not where the main rupture took place, and the area with slip greater than 0.5 m basically lies within 35 km deep middle-crust
under the earth surface. The maximum static slip is 3.6 m. There are two distinct areas with slip larger than 2.0 m. We noticed
that when the rupture propagated towards northwest and closed to the area around the M
S=7.3 hypocenter, the slip decreased rapidly, which may indicate that the rupture process was stopped by barriers. The consistence
of spatial distribution of slip on the fault plane with the distribution of aftershocks also supports that the rupture is
a heterogeneous process owing to the presence of barriers. 相似文献
132.
I. J. Simpson G. W. Thurtell H. H. Neumann G. Den Hartog G. C. Edwards 《Boundary-Layer Meteorology》1998,87(1):69-99
Flux-gradient relationships based upon similarity theory have been reported to severely underestimate scalar fluxes in the roughness sublayer above forests, as compared to independent flux estimates (for example, eddy covariance or energy balance measurements). This paper presents the results of a unique three-month investigation into the validity of similarity theory in the roughness sublayer above forests. Eddy covariance and flux-gradient measurements of carbon dioxide (CO2) exchange were compared above a mixed deciduous forest at Camp Borden, Ontario, both before and after leaf senescence. The eddy covariance measurements used a Li-Cor infrared gas analyzer, and the flux-gradient (similarity theory) measurements featured a tunable diode laser Trace Gas Analysis System (TGAS). The TGAS resolved the CO2 concentration difference to 300 parts per trillion by volume (ppt) based upon a half-hour sampling period. The measured enhancement factor (the ratio of independent flux estimates, in this case eddy covariance, to similarity theory fluxes) was smaller and occurred closer to the canopy than in most previous investigations of similarity theory. Very good agreement between the eddy covariance and similarity theory fluxes was found between 1.9 and 2.2 canopy heights (hc), and the mean enhancement factors measured before and after leaf senescence were 1.10 plusmn; 0.06 and 1.24 ± 0.07, respectively. Larger discrepancies were measured closer to the canopy (1.2 to 1.4 hc), and mean enhancement factors of 1.60 ± 0.10 and 1.82 ± 0.11 were measured before and after leaf senescence, respectively. Overall, the Borden results suggest that similarity theory can be used within the roughness sublayer with a greater confidence than previously has been believed. 相似文献
133.
134.
截直断裂是发育在大型的走滑或斜滑断裂带末端的分支断裂,断裂带长期反复活动,在其末端,因地壳应力消散或减弱,断裂走向发生急剧转折之后,在转折点附近产生了截直断裂,截直断裂的性状可以归纳为如下几点:(1)发育于接近主干断裂末端的转折点附近,其走向与主干断裂的总体走向一致,性状与主干断裂相似;(2)切割的地层或控制的沉积较的裂为新;(3)断裂的长度较小,断面较主干断裂为陡,(4)形成的时代为主干断裂发育 相似文献
135.
核废物处置已成为当务之急,其目的是要保证人类与环境的安全。普遍采用的方法是地质处置,即保寻安全封闭的天然屏障。为此,岩石的研究就至关重要。目前,各国选用的岩石不一,并不断变化,主要为石盐、粘土和花岗岩。开发研究总趋势是建立地下实验室,进行现场试验。 相似文献
136.
137.
一个典型的水下分流河道砂体展布与油气富集规律 总被引:2,自引:2,他引:2
三角洲一般位于海(湖)陆之间的过渡地带,是海(湖)陆相的重要组成部分。鄂尔多斯盆地三叠系延长组储层,由于其特殊的沉积环境.湖底坡降小.河控占主导地位.水下分流河道极为发育.最典型的是白120井区长33储层,由一个单一的水下分流河道组成。该区沉积规律强,各沉积单元发育,中间为河道沉积区,两侧为高于河道的天然堤,外部为漫溢沉积区,末端有4个朵体,中部发育一个小型决口水道。砂体呈指状展布,左右对称,具有三角洲水下分流河道典型的双凸特点。该区的沉积环境控制了砂体的展布和油气的富集程度。通过对该区块的研究,建立了一个完整的水下分流河道的沉积模式,这对于丰富三角洲沉积相的内容具有一定的意义。 相似文献
138.
小南海水库地震堰塞坝渗漏特征研究 总被引:7,自引:0,他引:7
从病害整治的角度论述了小南海水库地地震堰塞坝坝体本构特征,渗漏及渗透稳定、防渗处理措施等,并介绍了渗流量计算的解析法与系统理论法。 相似文献
139.
140.
随着射电望远镜口径增大、观测频率提高, 对其指向精度的要求也越来越高. 然而, 望远镜服役于野外台站, 台址风扰对天线指向精度的影响在高频段观测时已不能忽略. 由于风扰的时变性, 现有的抗风方法无法保障大口径高指向精度望远镜在高频段的有效观测时长. 因此, 提出了一种基于风障精确布置改善台址风环境的方法. 通过数值模拟构建了风障仿真模型, 并将仿真结果与风洞实测数据比较, 两种孔隙率风障的平均误差分别为3.7%和6.1%, 保证了风障模型的可靠性. 以新疆奇台射电望远镜(QiTai radio Telescope, QTT)台址为例, 基于QTT台址斜坡地形构建了计算域模型, 开展单风障不同高度、不同孔隙率的系列风场仿真试验, 得到了风障参量与下游挡风效果的关系. 基于单风障合理高度和最优孔隙率设置南北风障, 仿真结果表明在确定高度下最优孔隙率可以组合, 孔隙率0.1-0.1组合的风障挡风效果最优, 南方向来风在天线区域可以有效降低75%以上的风速. 相似文献