淄博矿震震源机制探讨

依据由分布密集测震台网记录而得到的地震波场介质力学参数分布特征、所在矿区地质构造与采煤概况,对淄博矿震发生成因及机制进行分析,发现矿震以张性破裂为主兼一定剪切破裂,拉张引起的岩体应变量远大于挤压引起的应变量,并具有一定双侧对称性.在震源发生破裂的过程中,震源周围变形的岩体应有一定回弹.     

Regional study on structural dynamic property of buildings in China

Full‐scale in situ ambient vibration tests have been performed in different regions of China since 2008. Reliable data on 35 buildings in the Sichuan province and 18 buildings in Shanghai have been used for identifying the structural dynamic properties. Every building was tested twice, at time intervals of 1 to 2 years. This paper first describes the statistical analysis results of the measured records and then the time–frequency domain analysis on dynamic responses of a specific monitored building subjected to strong motion. Furthermore, the estimated dynamic characteristics of the buildings are presented. The damping ratio shows a period‐dependent characteristic, and the natural periods of buildings in Sichuan shifted after 2 years. Subsequent discussion on the natural period change phenomenon reveals that the natural period changes are affected by a number of factors, including story number, construction year, loading history, and observation time intervals. The long‐term time effects on concrete, the self‐healing ability of cracked concrete, and the change in soil condition are discussed to explain the natural period wandering. Copyright © 2012 John Wiley & Sons, Ltd.     

Using finite element and Okada models to invert coseismic slip of the 2008 Mw 7.2 Yutian earthquake, China, from InSAR data

We invert InSAR from ascending and descending passes of ENVISAT/ASAR data to estimate the distribution of coseismic slip for the 2008 Mw 7.2 Yutian earthquake by separately using uniform finite element models (FEMs), non-uniform FEMs, and analytical elastic half-space (Okada) models. We use the Steepest Descent method and Laplacian smoothing to regularize and estimate the slip distribution for each of these different models. Fault surface ruptures interpolated from Quickbird optical images constrain the strike of the fault. The uniform FEM and Okada models assume a fault embedded in a homogeneous and elastic finite domain or half-space, respectively, while the non-uniform FEM describes a domain with spatially variable elastic properties according to the geological structure of Tibet plateau and Tarim. We find that the estimated slip distribution of the non-uniform FEM is similar to that of the uniform FEM but has a slightly larger moment (~2 %). However, more noticeable discrepancies occur between the slip distributions of the uniform FEM and Okada model, where the slip pattern estimated with the FEM looks more scattered and locates at a lower depth. We conclude that, for the case of the Yutian earthquake, the improvement brought by simulating the distribution of geologic material properties is insignificant. This suggests that the uniform geologic structure of Okada models may be sufficient for simulating large intra-continental earthquakes.     

Accumulated impact assessment of river buffer zone after 30 years of dam disturbance in the Yellow River Basin

As the buffer zone is the bridge between the river and surrounding territory, it experiences remarkable response to hydrological variance due to dam construction. To identify the accumulated impacts, two adjacent buffer zone sections of similar size on the Yellow River were compared. A time series of land cover distributions were analysed for changes of the buffer zones. After the dam service, a large area of wetlands and water area disappeared in the section with dam, which was also the consequence of the sedimentation in the reservoir. The areal extent for seven types of land cover was analysed in the buffer zone at distances of 10 and 5.5 km from the river. The land cover transition matrices within the 10 km zone for three time periods (1976–1996) were calculated to further clarify the transformation process. The farmland in the 10 km zone of dam increased 3 times in three decades, but it just rose the 50 % in the zone without dam. The land cover transition matrices analysis indicated that the major transitions in the dammed section were wetland, grassland and water area to farmland, as well as the mutual transformation of water area and wetlands. Two sections of the critical buffer zone within 5.5 km of the water were delineated into ten independent, 0.5 km annular gradient zones to determine the spatial variation of grassland, water area and wetland. The gradient zone analysis demonstrated that the dam construction accelerated the appearance of wetlands and also caused considerable pressure on the water and grassland area types. Upon comparing these temporal and spatial aspects, the increase of farmlands and wetlands in the earliest period was found to be the direct result of damming. The weakening hydrological alteration due to damming was concluded to significantly affect the temporal-spatial variations of the river buffer zone, particularly in the 5.5 km distance.     

The mesoscale eddies and Kuroshio transport in the western North Pacific east of Taiwan from 8-year (2003–2010) model reanalysis

The relationship between the Kuroshio volume transport east of Taiwan (~24°N) and the impinging mesoscale eddies is investigated using 8-year reanalysis of a primitive equation ocean model that assimilates satellite altimetry and SST data. The mean and fluctuations of the model Kuroshio transport agree well with the available observations. Analysis of model dynamic heights and velocity fields reveals three dominant eddy modes. The first mode describes a large eddy of ~500 km in diameter, centered at ~22° N. The second mode describes a pair of the north–south counter-rotating eddies of?~?400 km in diameter each, centered at 23° and 20° N, respectively. The third mode describes a pair of the east–west counter-rotating eddies of?~?300 km in diameter each, centered at 21° N. The associated velocity fields indicate eddies extending to 600–700 m in depth with vertical shears concentrated in the upper 400 m. All three modes and the model Kuroshio transport have similar dominant timescales of 70–150 days and generally are coherent. The decreased Kuroshio volume transports typically are associated with the impinging cyclonic eddies and the increased transports with the anticyclonic eddies. Selected drifter trajectories are presented to illustrate the three eddy modes and their correspondence with the varying Kuroshio transports.     

PCR-DGGE analysis of intestinal bacteria and effect of Bacillus spp. on intestinal microbial diversity in kuruma shrimp (Marsupenaeus japonicus)

In this study, the intestinal microbiota of kuruma shrimp (Marsupenaeus japonicus) was examined by molecular analysis of the 16S rDNA to identify the dominant intestinal bacteria and to investigate the effects of Bacillus spp. on intestinal microbial diversity. Samples of the intestines of kuruma shrimp fed normal feed and Bacillus spp. amended feed. PCR and denaturing gradient gel electrophoresis (DGGE) analyses were then performed on DNA extracted directly from the guts. Population fingerprints of the predominant organisms were generated by DGGE analysis of the universal V3 16S rDNA amplicons, and distinct bands in the gels were sequenced. The results suggested that the gut of kuruma shrimp was dominated by Vibrio sp. and uncultured gamma proteobacterium. Overall, the results of this study suggest that PCR-DGGE is a possible method of studying the intestinal microbial diversity of shrimp.     

利用IP传输技术改造武汉数字遥测地震台网系统

介绍如何利用IP通讯协议,通过Internet网络,实现改造地震台站观测设备与武汉数字遥测地震台网系统的信息集成。改造后的武汉数字遥测地震台网系统,提高了数字化资料高效性,满足了科学传递运行模式的需求,降低了台网传输故障率,减少了后期维护的人力和物力的投入。     

腾格里沙漠宁夏中卫沙层含水量研究

为了揭示腾格里沙漠地区沙层含水量、水分存在形式、运移和水分平衡等问题,对该沙漠东南部不同沙丘进行了含水量研究.结果显示,腾格里沙漠沙层含水量空间变化大,沙丘中、上部含水量低,下部与洼地含水量高.毛管水层指示毛管水上升高度一般为60 cm左右,毛管水层平均含水量为14.9%.由于研究区相对降水量偏多,沙层水分存在饱和重力水、毛管水、高含量薄膜水和低含量薄膜水等多种形式,在毛管水层之上的沙层水分一般均为薄膜水,5%左右的高含量薄膜水的存在是该区沙层水分含量的突出特点.沙层中薄膜水带的上、中、下部均有含水量较高的层段,表明该区大气降水经蒸发、蒸腾之后,仍有剩余的水分向下入渗,并成为地下水的补给来源.     

SAR遥感图像在汶川地震灾害识别中的应用

汶川地震发生后,受阴雨天气的影响,光学遥感影像在救灾决策中的作用受到了很大的限制,而SAR图像由于其全天候的特点成为这次抗震救灾前期遥感信息保障十分重要的数据源.采用ENVISAT的ASAR作为数据源,利用多时相的雷达数据的幅度及相位信息对映秀及周边地区做了地震灾害识别,其中利用震前震后的幅度图像做比值变化检测,在映秀镇及紫坪铺水库等山区取得了较好的效果;利用相位信息做干涉处理得到的相干图像,经过失相干分析,发现建筑物的破坏等级与相干系数变化指数的大小高度相关.比较这两种方法,在都江堰等平原地区由于失相干现象不像山区那么严重,并且利用比值处理可以去除部分空间失相干及系统热噪声等带来的干扰因素,可以成为幅度图像的有益补充.结果表明,结合SAR幅度影像和干涉相干影像,可以在地震灾害评估中取得更好效果.随着极化干涉雷达技术的日益成熟,多时相幅度信息、相位信息等多特征SAR影像信息的融合会在救灾决策中发挥更大的作用.     

Eclogite-melt/peridotite reaction: Experimental constrains on the destruction mechanism of the North China Craton

To study the mechanism of melt-peridotite reaction pertinent to the destruction of the North China Craton (NCC) lithosphere, a series of experiments were performed at a pressure of 2.0 GPa and temperatures from 1250 to 1400°C using Bixiling eclogite and Damaping peridotite as starting materials. The experimental results show that the reaction between eclogite melt and peridotite causes dissolution of olivine and orthopyroxene and precipitation of clinopyroxene in the melt. The experimental run products, cha...