Scaled amplification equation: A key to the folding history of buckled viscous single-layers     

Stefan M. Schmalholz   《Tectonophysics》2006,419(1-4):41-53

The presented equation describes amplitude growth during viscous single-layer folding (buckling) up to high amplitudes. The equation relates the dimensionless fold amplitude (i.e. ratio of amplitude to wavelength) to the stretch (ratio of initial wavelength to instantaneous wavelength) for given values of the viscosity contrast between layer and surrounding material and the initial ratio of amplitude to wavelength. The amplification equation is suitably scaled so that all amplitude versus stretch curves for different values of viscosity contrasts and initial amplitudes fall onto essentially a single curve. The scaled amplification equation allows for representing fold amplification of viscous single-layers by a singular curve. The scaling parameter is the crossover strain, which is an estimate for the amount of strain that is accumulated during the initial stages of folding where the amplitude grows exponentially with strain. The singular curve allows quantifying the universal boundaries between the three folding stages, namely nucleation, amplification and kinematic growth. The scaled amplification equation is verified by numerical (finite element method) simulations of folding of single layers with initial random perturbations of the layer interfaces. The amplification equation describes the amplification of single folds within fold trains successfully, although the folds are neither regular nor periodic and vary considerably in shape. The easily measurable parameters, vertical and horizontal hinge distance, are shown to be good approximations for the analytical parameters amplitude and wavelength, respectively.  相似文献   

Dependence of earthquake recurrence times and independence of magnitudes on seismicity history     

lvaro Corral 《Tectonophysics》2006,424(3-4):177

The fulfillment of a scaling law for earthquake recurrence–time distributions is a clear indication of the importance of correlations in the structure of seismicity. In order to characterize these correlations we measure conditional recurrence–time and magnitude distributions for worldwide seismicity as well as for Southern California during stationary periods. Disregarding the spatial structure, we conclude that the relevant correlations in seismicity are those of the recurrence time with previous recurrence times and magnitudes; in the latter case, the conditional distribution verifies a scaling relation depending on the difference between the magnitudes of the two events defining the recurrence time. In contrast, with our present resolution, magnitude seems to be independent on the history contained in the seismic catalogs (except perhaps for Southern California for very short time scales, less than about 30 min for the magnitude ranges analyzed).  相似文献   

Scaling Variances of Scalars in a Convective Boundary Layer Under Different Entrainment Regimes     

Arnold F. Moene  Berenice I. Michels  Albert A. M. Holtslag 《Boundary-Layer Meteorology》2006,120(2):257-274

For the presentation and analysis of atmospheric boundary-layer (ABL) data, scales are used to non-dimensionalise the observed quantities and independent variables. Usually, the ABL height, surface sensible heat flux and surface scalar flux are used. This works well, so long as the absolute values of the entrainment ratio for both the scalar and temperature are similar. The entrainment ratio for temperature naturally ranges from −0.4 to −0.1. However, the entrainment ratio for passive scalars can vary widely in magnitude and sign. Then the entrainment flux becomes relevant as well. The only customary scalar scale that takes into account both the surface flux and the entrainment flux is the bulk scalar scale, but this scale is not well-behaved for large negative entrainment ratios and for an entrainment ratio equal to −1. We derive a new scalar scale, using previously published large-eddy simulation results for the convective ABL. The scale is derived under the constraint that scaled scalar variance profiles are similar at those heights where the variance producing mechanisms are identical (i.e., either near the entrainment layer or near the surface). The new scale takes into account that scalar variance in the ABL is not only related to the surface flux of that scalar, but to the scalar entrainment flux as well. Furthermore, it takes into account that the production of variance by the entrainment flux is an order of magnitude larger than the production of variance by the surface flux (per unit flux). Other desirable features of the new scale are that it is always positive (which is relevant when scaling standard deviations) and that the scaled variances are always of order 1–10.  相似文献   

西藏羊八井地热田热水的化学组成   总被引：12，自引：0，他引：12       下载免费PDF全文

赵平  多吉 《地质科学》1998,33(1):61-72

羊八井地热田深、浅层热水都是Cl-Na类型,具有相同的B/Cl比值,说明深层热水在上升通道中与冷水相混合形成了浅层热水。浅层流体自西北向东南流动,温度逐渐降低。浅层热储内普遍存在着水岩交换反应,对热水的化学组成有一定的影响。石英和玉髓地热温度计分别适用于计算深、浅层的热储温度。纳木错(湖)不是羊八井地热田的补给区。深层热水在井筒内绝热汽化时不会出现SiO₂结垢,CaCO₃是否会在井筒壁沉淀需要放喷较长时间来检验。文中还阐述了对热水的化学组分进行监测的必要性。  相似文献   

裂隙网络多标度分形计算机模拟   总被引：1，自引：0，他引：1  

贾林  王士天 《地质灾害与环境保护》1997,8(3):48-53

岩体裂隙网络是不均匀，非对称的复杂分形，用简单分数维不能刻画其特征，必须采用多标度分形来研究，才能全面客观地描述其本质。文中介质了隙网络多标度分形计算机模拟原理与方法。  相似文献   

Evaluation of models for Fourier amplitude spectra for the Taiwan region     

Vladimir Sokolov  Chin-Hsiung Loh  Kuo-Liang Wen 《Soil Dynamics and Earthquake Engineering》2002,22(8)

In the Taiwan region, the empirical spectral models for estimating ground-motion parameters were obtained recently on the basis of recordings of small to moderate (5.0≤M_L≤6.5) earthquakes. A large collection of acceleration records from the M_L=7.3 Chi-Chi earthquake (21 September, 1999) makes it possible to test the applicability of the established relationships in the case of larger events. The comparison of ground-motion parameters (Fourier amplitude spectra, peak accelerations and response spectra), which were calculated using the models, and the observed data demonstrates that the models could provide an accurate prediction for the case of the Chi-Chi earthquake and the largest aftershocks. However, there are some peculiarities in the ground-motion frequency content and attenuation that, most probably, are caused by the features of the rupture process of the large shallow earthquake source.  相似文献   

用去趋势涨落分析研究北京气候的长程变化特征   总被引：2，自引：0，他引：2       下载免费PDF全文

郑祚芳  张秀丽  曹鸿兴  谢庄  潘家华 《地球物理学报》2007,50(2):420-424

无标度性广泛存在于自然界系统包括气候系统中，其特征之一是可观测量存在幂函数关系，它揭示了气候系统的复杂性.为探索气候可预测性的客观基础，运用去趋势涨落分析(DFA)方法对北京1870～2003 年平均气温和1725～2003年降水序列进行了分析.结果表明，北京年平均气温和降水量均可划分为多个标度不变区域.在特定的标度域内，它们都表现出正长程相关的性质，为制作年际与年代际气候预测提供了理论基础.  相似文献   

Apparent stress scaling and statistical trends     

Piotr Senatorski   《Physics of the Earth and Planetary Interiors》2007,160(3-4):230-244

Statistical relations between different earthquake parameters, such as M₀ (seismic moment), E_S (seismic energy), τ_a (apparent stress), A (rupture area), g (average slip acceleration), are investigated. For this purpose, a kinematic earthquake model representing averaged earthquake rupture process is formulated. The model implies a scaling relationship for τ_a as a function of three other parameters, related to kinematic (M₀), geometric (A) and material (g) source characteristics, which, according to the model, can change independently. This scaling relation is used to explain statistical trends that characterize different earthquake data sets (including micro-, small, moderate and large events) plotted in the log τ_a − log M₀ space, and to determine the area in this space, where typical earthquakes occur. The scaling relationship is interpreted in terms of the apparent stress minimum (i.e., the most uniform among the possible earthquake rupture patterns). It is concluded that, although the apparent stress increases on an average with increasing seismic moment, small and large earthquakes are essentially similar.  相似文献   

Diagnosing peak-discharge power laws observed in rainfall–runoff events in Goodwin Creek experimental watershed     

Peter R. Furey  Vijay K. Gupta 《Advances in water resources》2007

Observations from the Goodwin Creek experimental watershed (GCEW), Mississippi show that peak-discharge Q(A) and drainage area A are related, on average, by a power law or scaling relationship, Q(A) = αA^θ, during single rainfall–runoff events. Observations also show that α and θ change between events, and, based on a recent analysis of 148 events, observations indicate that α and θ change because of corresponding changes in the depth, duration, and spatial variability of excess-rainfall. To improve our physical understanding of these observations, a 5-step framework for diagnosing observed power laws, or other space-time patterns in a basin, is articulated and applied to GCEW using a combination of analysis and numerical simulations. Diagnostic results indicate how the power laws are connected to physical conditions and processes. Derived expressions for α and θ show that if excess-rainfall depth is fixed then there is a decreasing concave relationship between α and excess-rainfall duration, and an increasing and slightly convex relationship between θ and excess rainfall duration. These trends are consistent with observations only when hillslope velocity v_h is given a physically realistic value near 0.1 m/s. If v_h ? 0.1 m/s, then the predicted trends deviate from observed trends. Results also suggest that trends in α and θ can be impacted by the dependence of v_h and link velocity v_l on excess-rainfall rate.  相似文献   

Sea-breeze scaling from numerical model simulations,part II: Interaction between the sea breeze and slope flows     

Aurore Porson  Douw G. Steyn  Guy Schayes 《Boundary-Layer Meteorology》2007,122(1):31-41

Numerical model simulations of sea-breeze circulations in the presence of idealized topography are subjected to dimensional analysis in order to capture the dynamics of the sea-breeze circulation combined with an upslope-flow circulation. A secondary objective is to reconcile previous results based on observations. The analysis is based on a scaling analysis of sea-breeze speed, depth and volume flux. This study is motivated by the fact that the literature of sea breezes interacting with upslope flows is generally qualitative. Results show clear scaling regimes and strong interaction between the two thermally driven circulations. We distinguish three regimes, depending on slope length, slope angle, stability and surface heat flux. The first and third regimes obey the scaling laws of pure sea-breeze scaling. The second regime shows a significant decrease in the scaled volume flux relative to pure sea-breeze scaling. Dynamical relations in the second regime show a strong influence on the circulation of upslope stable air advection.  相似文献