数字形变观测的高频抖动信号对地震前兆响应分析     

何香玲  刘学谦  苏莉华 《地震地磁观测与研究》2011,32(6):116-121

通过对河南荥阳地震台水管观测记录中的60例“高频抖动信号”,与周围250 km范围内地震事件在时间域的前兆响应的统计分析,结果表明,这种信号与地震事件之间具有一定程度的前兆响应关系.认为该高频抖动信号与周围地震具有内在的关联性,是地壳形变过程的一种前兆反应,具有一定的前兆意义.  相似文献   

基于小波分析的闽台地区地震形变异常研究     

钟继茂  陈光  刘其寿 《华北地震科学》2011,29(1):30-35

在孕震过程的不同阶段,可能会有长、中、短期前兆异常表现.为揭示闽台地区几次中强地震前不同时期的异常形态,对福建省数字化形变观测资料日均值、整点值和分钟值时序数据进行小波分析,结果发现:在强震前2～3年出现周期2年左右的异常信号;在中强地崖前2～5个月出现周期1个月左右的异常信号;在震前几天至十几天则出现周期半小时至1小...  相似文献   

A parameterization of the wavelength of tidal dunes     

Paolo Blondeaux  Giovanna Vittori 《地球表面变化过程与地形》2011,36(9):1152-1161

The idealized model of Besio et al. (On the formation of sand waves and sand banks. Journal of Fluid Mechanics 2006; 557: 1–17) is used to predict the wavelength of tidal dunes (sand waves) generated by tidal currents in estuaries and shallow seas. The predictions are then analysed and a formula is proposed to estimate the wavelength of tidal dunes as a function of the parameters of the problem. The wavelength of the dunes is found to increase when the water depth is increased and/or the strength of the tidal current is decreased. On the other hand, the size of the bottom material (if medium sand is considered) and the tidal ellipticity are found to have a relatively small influence on the length of the bottom forms. The formula proposed provides results which are consistent with field observations of different authors. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

A channel head stability criterion for first‐order catchments     

Péter B. Sólyom 《地球表面变化过程与地形》2011,36(4):533-546

The present analysis derives a stability criterion for long‐term equilibrium channel heads. The concept of finite perturbation analysis is presented, during which the surface is subjected to perturbations of a finite amplitude and resulting changes in flow path structure and slope are computed. Based on these quantities the analysis predicts whether the perturbed location is going to erode, be filled in or remain steady. The channel head is defined geometrically as the focus point of converging flow lines at the bottom of hollows. It is demonstrated that stability at the channel head grows out of the competition between the rate of flow path convergence and the degree of profile concavity. Analytical functions are derived to compute channel head‐contributing area and ‐slope, flow path convergence and profile concavity as a function of perturbation depth, distance from the crest and the initial slope. In a numerical model these quantities point to the long‐term equilibrium channel head position, which is shown to depend also on the width to length ratio of hollows. It is also demonstrated that the equilibrium channel head position is sensitive to the base‐level lowering/non‐dimensional slope length ratio and to the slope of the initial topography. Morphometrical measurements both in the field and on simulated topographies were used to test the theoretical predictions.  相似文献   

南京地区地球物理场与地震构造稳定性   总被引：2，自引：1，他引：1       下载免费PDF全文

熊振  李清河  王良书  周彩霞 《地震学报》2011,33(5):624-636

岩石圈的不均衡状态是地球物理场存在差异的原因,对区域地球物理场进行分析,可以了解岩石圈的不均衡及其构造活动的背景.本文在对南京地区地震地质环境分析的基础上,通过重力异常、地热场、深部速度结构、天然地震层析成像等地球物理资料进行系统分析,研究它们与本区地震构造稳定性的关系;分析研究地震活动,从现今地壳运动速度场与地壳形变...  相似文献   

云南地区的背景弹性波场分析          下载免费PDF全文

赵琳  安美建  沈旭章  代光辉  田建雄 《地震学报》2011,33(6):723-734

利用云南省地震台网44个台站记录的2008年1-9月连续波形数据进行互相关计算,得到了台站间的格林函数,并获取对应的频散曲线,据此分析了该地区的区域背景弹性波场的来源及分布.研究发现,该地区的区域背景弹性波场有着明显的方向性,15s信号的总体传播方向是从东南向西北,也就是说主要来自云南省的东南方向,据此推测区域背景弹性...  相似文献   

Evaluating restoration of man‐made slopes: a threshold approach balancing vegetation and rill erosion     

Mariano Moreno‐de las Heras  Rubén Díaz‐Sierra  José M. Nicolau  Miguel A. Zavala 《地球表面变化过程与地形》2011,36(10):1367-1377

The management of reclaimed slopes derived from industrial and civil activities (e.g. surface mining and road construction) requires the development of practical stability analysis approaches that integrate the processes and mechanisms that rule the dynamics of these ubiquitous emerging ecosystems. This work describes a new modelling approach focused on stability analysis of water‐limited reclaimed slopes, where interactive relationships between rill erosion and vegetation regulate ecosystem stability. Our framework reproduces two main groups of possible trends along the temporal evolution of reclaimed slopes: successful trends, characterized by widespread vegetation development and the effective control of rill erosion processes; and gullying trends, characterized by the progressive loss of vegetation and a sharp logistic increase in erosion rates. Furthermore, this analytical approach allows the determination of threshold values for the state variables (i.e. vegetation cover and rill erosion) that drive the system's stability, facilitating the identification of critical situations that require specific human intervention (e.g. revegetation or, in very problematic cases, revegetation combined with rill network destruction) to ensure the long‐term sustainability of the restored ecosystem. The application of our threshold analysis framework in Mediterranean‐dry reclaimed slopes derived from surface coal mining (the Teruel coalfield in central‐eastern Spain) showed a good field‐based performance. Therefore, we believe that this model is a valuable contribution for the management of water‐limited reclaimed systems, including those associated with rill erosion, as it provides a tool for the evaluation of restoration success and can play an important role in decision‐making during ecosystem restoration in severely disturbed landscapes. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

河流相储层特征及识别:一个老河口油田的实例分析(英文)   总被引：4，自引：1，他引：3  

张军华  刘振  朱博华  冯德永  张明振  张学芳 《应用地球物理》2011,8(3):181-188

河流相储层是一种重要的储层类型,寻找河道砂体是油气勘探的一项重要工作。但是河道变迁比较频繁,叠置比较严重,加之地震资料本身信噪比和分辨率的限制,河流相储层的精细描述至今仍存在一定的困难。本文以胜利油田老河口三维工区为例,首先研究了本区河流相储层的基本特征,发现该类储层剖面上呈强相位、切片上连续性好和频谱上呈低频特征;通过颜色处理和地震精细解释,发现本区河流相储层存在类串珠状特征,为了验证这一观测结果,我们用正演模拟分析了其形成机理,为在类似工区识别此类古河道找到了新的途径;应用多属性融合和RGB显示技术,河道下切特征更加明显,很好地彰显了河道结构特征,提高了河道识别能力;最后,我们研究并开发了多子波检测技术,检测出更多河流相弱反射信息。  相似文献   

桂平市气象参数对大气环境评价的影响     

杨玉静 《气象研究与应用》2011,32(4):54-56,76

通过收集可代表桂平市气象条件2010年的气象资料,对该气象站的不同观测频率气象参数的统计结果进行了对比分析,得出风向频率玫瑰图、污染系数图、大气稳定度,并论述了其对大气环境评价的影响,得出桂平市的大气输送通道。  相似文献   

青海木里冻土区水合物稳定带的特征研究——模拟与钻探结果对比   总被引：4，自引：1，他引：3       下载免费PDF全文

金春爽  乔德武  卢振权  祝有海  张永勤  文怀军  李永红  王平康  黄霞 《地球物理学报》2011,54(1):173-181

基于青海木里冻土区的气体组成、钻孔泥浆的温度测量数据等对该区水合物稳定带的顶底深度进行了模拟计算,并将计算结果与钻探揭示的水合物产出深度进行了对比.模拟计算的水合物顶深在148.8～122.7 m 间,底深在324.6～354.8 m间,水合物厚度在175.8～232.2 m间,钻探揭示水合物及其异常产出在133～39...  相似文献