地表探槽断裂岩岩石磁学揭示汶川地震断裂带不同滑移机制   总被引：3，自引：0，他引：3  

刘栋梁  李海兵  李德贵  孙知明  司家亮  王焕 《地质学报》2015,89(12):2250-2265

岩石磁学能揭示岩石的磁性矿物组合,通过断裂岩不同的磁性矿物组合可揭示地震过程中磁性矿物变化、地震摩擦温度及地震滑移机制等基础地震地质问题。2008年Mw 7.9级汶川地震使两条断裂带同时发生地表破裂,包括映秀-北川和灌县-安县断裂地表破裂带,破裂带上地震断裂岩为岩石磁学提供了大量的研究对象。本研究主要以汶川地震地表破裂带上两个探槽内断裂岩为对象,包括映秀-北川地表破裂带上的八角庙探槽和灌县-安县地表破裂带上的九龙探槽,结合目前已发表的地表及WFSD-1孔的研究成果,从岩石磁学角度探讨汶川地震断裂带经历的地震滑移机制:1综合映秀-北川地震断裂带上八角庙探槽和其它位置的断裂岩岩石磁学研究,结果显示该地震断裂带附近断层泥的高磁化率源于新生的亚铁磁性矿物,如磁铁矿和磁赤铁矿等,故映秀-北川地震断裂曾经历高温快速热增压地震滑移机制;2灌县-安县地震断裂带上九龙探槽内断层泥略低的平均磁化率源于其铁的硫化物含量比断层角砾及侏罗纪砂岩多,铁的硫化物可能源于地震过程或断裂岩抬升到地表后的地表作用,如果断层泥中铁的硫化物多含量源于地震过程,则灌县-安县地震断裂带曾经历低温慢速机械润滑地震滑移机制;3两条断裂经历的不同地震滑移机制可能受控于断裂深部结构,如断层产状,映秀-北川地震断裂带的陡倾角易产生高温快速地震滑移,而灌县-安县地震断裂带的缓倾角更易产生低温慢速地震滑移。  相似文献   

Progressive failure leading to the 3 December 2013 rockfall at Puigcercós scarp (Catalonia,Spain)   总被引：1，自引：1，他引：0  

Manuel?J.?RoyánEmail author  Antonio?Abellán  Joan?Manuel?Vilaplana 《Landslides》2015,12(3):585-595

A detailed analysis of the pre-failure behavior of the 3 December 2013 rockfall (1,012 m³) occurred on Puigcercós pilot study area (Catalonia, Spain) is presented. The exact date of failure was obtained based on a photographic monitoring performed every 4 h. The long-term monitoring (2,217 days) of the rock slope carried out by a Terrestrial LiDAR allowed the early detection of both pre-failure deformation and precursory rockfalls preceding the final failure. By means of the analysis of the pre-failure deformation, four different deformed areas were detected and the tertiary creep phase was observed in three of them. An attempt to predict the time to failure was performed using the Fukuzono’s (1985) method. Furthermore, the temporal evolution of the precursory rockfalls occurred in those four areas during the progressive failure showed a close resemblance with the exponential pattern of the cumulated displacements at tertiary creep stage. Finally, the study of the meteorological conditions did not show any single triggering factor associated with the final failure. Reversely, the increase in the occurrence of precursory rockfalls on several areas of the slope together with the observed acceleration on the deformation pattern reinforce the role of a progressive degradation of the stability conditions, which ultimately leaded to the 3 December rockfall event.  相似文献   

Time-Dependent Modulation of Cosmic Rays in the Heliosphere     

R. Manuel  S. E. S. Ferreira  M. S. Potgieter 《Solar physics》2014,289(6):2207-2231

The time-dependent modulation of galactic cosmic rays in the heliosphere is studied by computing intensities using a time-dependent modulation model. By introducing recent theoretical advances in the transport coefficients in the model, computed intensities are compared with Voyager 1, International Monitoring Platform (IMP) 8, and Ulysses proton observations in search of compatibility. The effect of different modulation parameters on computed intensities is also illustrated. It is shown that this approach produces, on a global scale, realistic cosmic-ray proton intensities along the Voyager 1 spacecraft trajectory and at Earth up to ≈?2004, whereafter the computed intensities recover much more slowly towards solar minimum than observed in the inner heliosphere. A modified time dependence in the diffusion coefficients is proposed to improve compatibility with the observations at Earth after ≈?2004. This modified time dependence led to an improved compatibility between computed intensities and the observations along the Voyager 1 trajectory and at Earth even after ≈?2004. An interesting result is that the cosmic-ray modulation during the current polarity cycle is not determined only by changes in the drift coefficient and tilt angle of the wavy current sheet, but is also largely dependent on changes in the diffusion coefficients.  相似文献   

Iconography of the 1755 Lisbon Earthquake     

Manuel S. Pinto 《《幕》》2006,29(3):227-228

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Numerical evaluation of the dilogarithm of complex argument     

Carlos Osácar  Jesús Palacián  Manuel Palacios 《Celestial Mechanics and Dynamical Astronomy》1995,62(1):93-98

A numerical algorithm to evaluate the dilogarithmic function of a complex argument is proposed. The use of the dilogarithm in celestial mechanics appears in the exact Delaunay normalization of some functions involving the equation of the centre.  相似文献   

Mathematical model for one-dimensional desiccation and consolidation of sedimented soils     

Manuel Casteleiro  Raymond J. Krizek  Tuncer B. Edil 《国际地质力学数值与分析法杂志》1981,5(2):195-215

A mathematical model has been developed to represent the physical phenomena that occur during the desiccation and one-dimensional consolidation of successive layers of hydraulically transported sediments as they are periodically deposited in a containment area. The governing boundary value problem, defined in terms of pore water pressures, consists of two field equations (one for the saturated domain and one for the unsaturated domain), a drainage boundary condition, an evapotranspiration boundary condition and a series of continuity conditions at the interfaces between different layers. A number of simplifying assumptions were made to render the field equations tractable, and a step-by-step numerical procedure was used to solve the linearized boundary value problem; at the end of each step, the errors introduced by the simplifying assumptions were corrected. Based on a thorough study of the convergence and stability conditions associated with the numerical approximation employed, a system of automatic corrections was incorporated into the computer program to reduce the time increment if stability problems originate during the solution. Based on the results of a parameter study, it was found that, although drainage conditions at the bottom of the, layer do exert some influence on the consolidation rate during deposition of the dredgings, the evapotranspiration potential renders this effect almost negligible when desiccation takes place at the surface. In contrast, transpiration plays an important, role on the consolidation rate during the early stages of desiccation, but its effect is reduced considerably as the water table approaches an equilibrium position.  相似文献   

The lyman alpha line in solar prominences     

Fontenla  Juan Manuel  Rovira  Marta 《Solar physics》1983,85(1):141-156

Solar Physics - We present simplified models for the region where Lα is formed, in the boundary between prominences and corona. The models were calculated by solving the radiation transfer in...  相似文献   

Seismic risk in Turkey, the Aegean and the eastern Mediterranean: the occurrence of large magnitude earthquakes   总被引：1，自引：0，他引：1  

Paul W. Burton  Robert McGonigle  Kostas C. Makropoulos  S. Balamir Üçer 《Geophysical Journal International》1984,78(2):475-506

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Runoff generation and routing on artificial slopes in a Mediterranean–continental environment: the Teruel coalfield,Spain     

Jos‐Manuel Nicolau 《水文研究》2002,16(3):631-647

The aim of this study was to identify the mechanisms of runoff generation and routing and their controlling factors at the hillslope scale, on artificial slopes derived from surface coal mining reclamation in a Mediterranean–continental area. Rainfall and runoff at interrill and microcatchment scales were recorded for a year on two slopes with different substrata: topsoil cover and overburden cover. Runoff coefficient and runoff routing from interrill areas to microcatchment outlets were higher in the overburden substratum than in topsoil, and greater in the most developed rill network. Rainfall volume is the major parameter responsible for runoff response on overburden, suggesting that this substratum is very impermeable—at least during the main rainfall periods of the year (late spring and autumn) when the soil surface is sealed. In such conditions, most rainfall input is converted into runoff, regardless of its intensity. Results from artificial rainfall experiments, conducted 3 and 7 years after seeding, confirm the low infiltration capacity of overburden when sealed. The hydrological response shows great seasonal variability on the overburden slope in accordance with soil surface changes over the year. Rainfall volume and intensities (I₃₀, I₆₀) explain runoff at the interrill scale on the topsoil slope, where rainfall experiments demonstrated a typical Hortonian infiltration curve. However, no correlation was found at the microcatchment level, probably because of the loss of functionality of the only rill as ecological succession proceeded. The runoff generation mechanism on the topsoil slope is more homogeneous throughout the year. Runoff connectivity, defined as the ratio between runoff rates recorded at the rill network scale and those recorded at the interrill area scale in every rainfall event, was also greater on the rilled overburden slope, and in the most developed rill network. The dense rill networks of the overburden slope guarantee very effective runoff drainage, regardless of rainfall magnitude. Rills drain overland flow from interrill‐sealed areas, reducing the opportunity of reinfiltration in areas not affected by siltation. Runoff generation and routing on topsoil slopes are controlled by grass cover and soil moisture content, whereas on overburden slopes rill network density and soil moisture content are the main controlling factors. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

WOMEN AND GEOGRAPHY IN SPANISH UNIVERSITIES     

M. Dolores García-Ramn  Margarida Castaer  Núria Centelles 《The Professional geographer》1988,40(3):307-315

An analysis of the presence of women geographers in Spanish universities indicates that women lecturers are a minority, especially in the top posts. The written contributions of women geographers in geographical journals published by geography departments, and in unpublished M.A. theses and doctoral dissertations are proportionally fewer than the corresponding percentage of staff members.  相似文献