中国大陆中强以上地震余震分布尺度的统计特征   总被引：10，自引：0，他引：10       下载免费PDF全文

蒋海昆  郑建常  吴琼  曲延军  李永莉  代磊 《地震学报》2007,29(2):151-164

依据1970年以来记录相对完备的MSge;5.0地震序列资料，统计研究了中国大陆余震分布尺度与序列最大地震震级M0及最大地震破裂形式之间的关系. 在95%置信概率下，考虑主震破裂形式， 分序列类型给出了余震分布尺度与M0之间的统计关系. 定性而言，余震分布尺度的对数lgR与M0正相关， 但数据分布较为离散. 分类型来看， 孤立型序列余震分布尺度与M0之间统计相关程度低， 余震分布尺度介于5~60 km之间； 主余型序列lgR与M0正相关； 多震型序列当M0le;6.2时lgR与M0之间相关性不显著，余震分布尺度介于5~70 km之间， 当M0ge;6.3时lgR与M0线性相关. 统计结果还表明， 走滑近走滑及斜滑型主震所导致序列类型比例之间没有显著差异，而倾滑近倾滑型主震（主要为逆断型破裂）所导致的主余型序列所占比例较高， 孤立型及多震型序列所占比例则相对较低. 对比研究显示， 当M0较高时，余震分布尺度主要取决于主震大小而与主震破裂形式关系不明显.   相似文献   

Analysis of Fog Probability from a Combination of Satellite and Ground Observation Data   总被引：1，自引：0，他引：1  

Vincent Guidard  Diane Tzanos 《Pure and Applied Geophysics》2007,164(6-7):1207-1220

The Cloud Type product, developed by the Satellite Application Facility to support to nowcasting and very short-range forecasting (SAFNWC) of EUMETSAT and based on Météosat-8/SEVIRI, identifies cloud categories, and especially low and very low clouds which are first estimates of areas where fog is likely to occur. This cloud type is combined with precipitation information from radar data and with hourly diagnostic analyses of 2-metre relative humidity and 10-metre wind to elaborate an hourly analysis of fog probability. This analysis provides four levels of fog probability with a 3-kilometre horizontal resolution: No risk, low-level risk, medium-level risk and high-level risk. An evaluation of such fog probability analyses versus a one-year set of French hourly SYNOP reports shows encouraging results (potential of detection = 0.73 for low and medium and high-level risks), even if false alarm ratios remain high. Most of the non-detections occur at twilight and are due to satellite non-detections. Eventually, we show case studies that clearly illustrate the high potential of the method.  相似文献   

Investigating the amount of zeroing in modern sediments of River Danube, Austria     

Markus Fiebig  Frank Preusser 《Quaternary Geochronology》2007,2(1-4):143-149

Sediments attributed to flooding events of River Danube concerning the bleaching of the optical stimulated luminescence (OSL) signal were investigated. It is demonstrated that the OSL signal in both quartz and feldspar is not completely but differentially bleached in the sediment grains. Partial bleaching of the samples is clearly indicated by the scatter of equivalent dose determined for several individual single aliquots. It is also shown that residual ages in feldspars are significantly higher than those calculated for quartz. It is furthermore demonstrated that analysing measurement-time dependent equivalent dose estimates is not a suitable method to identify partial bleaching in the investigated sediment grains. However, the transport and deposition process of the investigated samples was probably disturbed by an artificial input of sediment, and this case study may thus not be representative of undisturbed high flood events in the past.  相似文献   

广东省地面塌陷特征及防治对策   总被引：2，自引：0，他引：2  

易顺民 《中国地质灾害与防治学报》2007,18(2):127-131

广东省的地面塌陷主要有自然塌陷及人为塌陷等2种类型。其中人为塌陷包括抽排水塌陷及采空区塌陷。地面塌陷的平面形态多呈圆形、椭圆形、长条形和不规则形等;剖面形态大致可分为竖井状、蝶状、漏斗状及坛状等。从区域上看,地面塌陷的分布特征受地形地貌、地质构造、地下水作用特征、岩溶发育程度、覆盖层条件和人类工程活动等的控制。探讨了广东省地面塌陷的防治对策。  相似文献   

鄂北杭锦旗地区下石盒子组储层物性特征及评价   总被引：1，自引：0，他引：1  

曹敬华  周文  邓礼正  李秀华  刘飞 《物探化探计算技术》2007,29(1):30-34

杭锦旗地区位于鄂尔多斯盆地北部伊盟隆起杭锦旗断阶带上,下石盒子组为辫状河和河流相沉积。通过薄片观察、岩心物性分析和压汞曲线实验,对岩石学特征、物性特征、孔隙结构特征进行了分析。结果表明:下石盒子组砂岩储层孔隙类型,主要有剩余原生粒间孔、次生孔隙和高岭石晶间隙;裂缝不发育;孔隙结构可分为细喉微孔型、粗喉大孔型和细喉中孔型三类,其中以细喉中孔型为主。储层为中低孔、低渗储层,盒3段物性最好。利用径向基神经网络解释的孔隙度参数在岩心实验校正后进行储层平面分布评价,结果表明:锦2、锦6～锦7井区是下石盒子组有利发育带。  相似文献   

孤岛西南缘馆陶组油气水分布特征及油气成藏规律     

李莉  徐国盛  刘树根  何建军  孙玮 《物探化探计算技术》2007,29(2):120-124

孤岛西南缘位于济阳坳陷沾化东部地区,其馆陶组为一套砂砾岩与泥岩互层层系,岩性馆上段较细,下段则较粗。该区的油气分布垂向上多分布在馆上段,并呈现上稀下稠的状态;侧向上主要分布在该区的中部偏东地区,集中在圈闭的高部位。在混源充注、断层疏导、网毯式捕集、泥盖立体成藏的成藏机理下形成了垂向断层运移,侧向块砂运移,高部位油气聚集成藏的特点。  相似文献   

辽河流域人发中重金属元素分布特征   总被引：4，自引：0，他引：4  

乌爱军  杨晓波马力于成广  王丹阳 《岩矿测试》2007,26(4):305-308

对辽河流域人发中重金属元素含量分布、分配规律研究结果表明：重金属元素尤其是铅、镉、汞、砷、铬元素，分布规律有很大相同之处，高含量数据点均围绕沈阳、锦州等重工业城市及阜新、柴河铅矿及其下游等地区分布，且城市居民平均含量明显高于乡村居民平均水平。通过进一步对典型污染区的研究发现：人发分布特征与背景环境有很大相关性，即土壤、浅层地下水、作物中重金属含量高的地区，人发中重金属含量亦较高。  相似文献   

河北省褐煤资源赋存分布特征与勘查开发利用前景分析     

张国斌  刘现川 《中国煤田地质》2007,19(6):17-18,32

河北省辖区内赋存、分布的褐煤资源形成于早白垩世和第三纪，但由于煤层顶底板岩石固结程度差，建井开采时井巷变形严重，维护困难，致使大量褐煤资源未得以开发利用。根据已有资料分析，褐煤含煤区地质构造条件简单、水文地质条件简单、主要呵采煤层顶板以泥岩或炭质泥岩为主，岩石致密，透气性差。褐煤本身透气性好，燃点低，没有粘结性，挥发分高．受热容易膨胀破裂，诸多因素都表明适合采用煤炭地下气化的开采方式进行开发利用，因此有必要加强我省褐煤资源的地质勘查工作和煤炭地下气化工艺的研究，为今后褐煤开发利用奠定基础。  相似文献   

Turbidite bed thickness distributions: methods and pitfalls of analysis and modelling     

ZOLTÁN SYLVESTER 《Sedimentology》2007,54(4):847-870

Turbidite bed thickness distributions are often interpreted in terms of power laws, even when there are significant departures from a single straight line on a log–log exceedence probability plot. Alternatively, these distributions have been described by a lognormal mixture model. Statistical methods used to analyse and distinguish the two models (power law and lognormal mixture) are presented here. In addition, the shortcomings of some frequently applied techniques are discussed, using a new data set from the Tarcău Sandstone of the East Carpathians, Romania, and published data from the Marnoso‐Arenacea Formation of Italy. Log–log exceedence plots and least squares fitting by themselves are inappropriate tools for the analysis of bed thickness distributions; they must be accompanied by the assessment of other types of diagrams (cumulative probability, histogram of log‐transformed values, q–q plots) and the use of a measure of goodness‐of‐fit other than R², such as the chi‐square or the Kolmogorov–Smirnov statistics. When interpreting data that do not follow a single straight line on a log–log exceedence plot, it is important to take into account that ‘segmented’ power laws are not simple mixtures of power law populations with arbitrary parameters. Although a simple model of flow confinement does result in segmented plots at the centre of a basin, the segmented shape of the exceedence curve breaks down as the sampling location moves away from the basin centre. The lognormal mixture model is a sedimentologically intuitive alternative to the power law distribution. The expectation–maximization algorithm can be used to estimate the parameters and thus to model lognormal bed thickness mixtures. Taking into account these observations, the bed thickness data from the Tarcău Sandstone are best described by a lognormal mixture model with two components. Compared with the Marnoso‐Arenacea Formation, in which bed thicknesses of thin beds have a larger variability than thicknesses of the thicker beds, the thinner‐bedded population of the Tarcău Sandstone has a lower variability than the thicker‐bedded population. Such differences might reflect contrasting depositional settings, such as the difference between channel levées and basin plains.  相似文献   

广西冰雹气候统计分析及减灾对策   总被引：2，自引：0，他引：2  

姚胜芳黄治逢  农孟松唐文 《广西气象》2007,28(4):22-25

统计分析了1956年以来以来广西冰雹的时空分布特征及影响因子,并提出了减灾对策。广西冰雹集中在2～5月,主要发生在14～19时;北多南少,西多东少,山区比沿海多;大范围冰雹过程可分为高原东部深槽型;南支槽型;华北深槽型。其中南支槽是冰雹天气的最主要系统;冰雹次数与拔海高度正相关,与年平均气温负相关。  相似文献