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101.
Statistical analysis of time-dependent earthquake occurrence and its impact on hazard in the low seismicity region Lower Rhine Embayment 总被引:1,自引:0,他引:1
Licia Faenza Sebastian Hainzl Frank Scherbaum Céline Beauval 《Geophysical Journal International》2007,171(2):797-806
The time-dependence of earthquake occurrence is mostly ignored in standard seismic hazard assessment even though earthquake clustering is well known. In this work, we attempt to quantify the impact of more realistic dynamics on the seismic hazard estimations. We include the time and space dependences between earthquakes into the hazard analysis via Monte Carlo simulations. Our target region is the Lower Rhine Embayment, a low seismicity area in Germany. Including aftershock sequences by using the epidemic type aftershock-sequence (ETAS) model, we find that on average the hypothesis of uncorrelated random earthquake activity underestimates the hazard by 5–10 per cent. Furthermore, we show that aftershock activity of past large earthquakes can locally increase the hazard even centuries later. We also analyse the impact of the so-called long-term behaviour, assuming a quasi-periodic occurrence of main events on a major fault in that region. We found that a significant impact on hazard is only expected for the special case of a very regular recurrence of the main shocks. 相似文献
102.
E. B. Pestchevitskaya 《Stratigraphy and Geological Correlation》2007,15(6):577-609
The described scheme of the Lower Cretaceous (Berriasian-Barremian) stratigraphic subdivisions is elaborated based on palynological study of sections in the Khatanga depression, Ust-Yenisei region, Pur-Taz interfluve, and around the Ob River latitudinal segment, the North Siberia. Stratigraphic distribution of microphytoplankton studied in detail is used to distinguish 10 biostratigraphic units in the rank of dinocysts zones. Stratigraphic position of the zones is determined with confidence using data on the Lower Cretaceous reference sections in the Khatanga depression, which were principal ones by constructing the Boreal standard zonation. In majority, boundaries of the dinocysts beds are of a high correlation potential and can be regarded as reliable stratigraphic markers, as they are recognizable not only in Siberia, but also in northern Europe and America. 相似文献
103.
Peter Doucette Peggy Agouris Anthony Stefanidis Mohamad Musavi 《ISPRS Journal of Photogrammetry and Remote Sensing》2001,55(5-6)
The extraction of road networks from digital imagery is a fundamental image analysis operation. Common problems encountered in automated road extraction include high sensitivity to typical scene clutter in high-resolution imagery, and inefficiency to meaningfully exploit multispectral imagery (MSI). With a ground sample distance (GSD) of less than 2 m per pixel, roads can be broadly described as elongated regions. We propose an approach of elongated region-based analysis for 2D road extraction from high-resolution imagery, which is suitable for MSI, and is insensitive to conventional edge definition. A self-organising road map (SORM) algorithm is presented, inspired from a specialised variation of Kohonen's self-organising map (SOM) neural network algorithm. A spectrally classified high-resolution image is assumed to be the input for our analysis. Our approach proceeds by performing spatial cluster analysis as a mid-level processing technique. This allows us to improve tolerance to road clutter in high-resolution images, and to minimise the effect on road extraction of common classification errors. This approach is designed in consideration of the emerging trend towards high-resolution multispectral sensors. Preliminary results demonstrate robust road extraction ability due to the non-local approach, when presented with noisy input. 相似文献
104.
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106.
大都市政府和都市议会是发达国家对大都市区和都市连绵区进行宏观管理的重要机构,本文简要介绍了各种类型的大都市政府和都市议会的形成与发展,在此基础上提出了我国相应的宏观管理机构为城镇密集区政府和都市区规划局,最后,对我国城镇密集区规划管理的可行性与规划管理体系问题进行了讨论。 相似文献
107.
Mohamed M. Abu-Zeid Ashraf R. Baghdady Hassan A. El-Etr 《Journal of Arid Environments》2001,48(4):475
Sand dunes and interdune sediments around Al Ain city have markedly high carbonate contents which increase towards Jabal Hafit mountain and the Arabian Gulf coast. The dunes are composed predominantly of well-sorted fine sands, consisting of unstrained quartz and carbonate grains together with minor proportions of chert and feldspars. Scanning electron microscope (SEM) examination reveals that quartz grains display various mechanically- and chemically-formed surface textures. The heavy minerals are dominated by opaques and pyroxenes with minor tourmaline, garnet, rutile, epidote, monazite, zircon, hornblende and staurolite.Interdune sediments consist of fine and very fine, poorly- to extremely poorly-sorted sands together with small concentrations of gravel, silt and clay. The light sand fractions compositionally resemble those of dunes but contain, in addition, gypsum, anhydrite, halite and celestite. Percentages of pyroxenes are higher whereas those of zircon, tourmaline and rutile are lower than in dunes. X-ray diffractometry reveals that the clay fractions consist solely of palygorskite. Generally, interdune sediments are much less mature texturally and mineralogically than dune sands; the maturity of both types of sediments decreases toward the NE of the study area.Sand dunes in the various districts of the greater Al Ain area are genetically related. Also, there is a partial genetic relationship between the dunes and interdune sediments; both are mainly multicyclic. Their major parts were brought mainly by the dominant north-west (El Shamal) winds from older dune fields in other localities in U.A.E., Qatar and El-Rub El-Khali. Local contributions to the dune fields from Jabal Hafit mountain, the Oman Mountains and the calcareous coast of the Arabian Gulf were, in cases, significant. Also, authigenesis by groundwater under highly evaporitic conditions played a major role in the formation of interdune sediments through the genesis of the clay and some nonclay minerals. 相似文献
108.
Oren Yiftachel 《GeoJournal》2001,53(3):283-293
This paper uses a critical political-geographical perspective to account for the high centrality of power found in Israel. It suggests that the concentration of power have not been solely caused by national solidarity and integration or by metropolitan development, as commonly explained, but also by the territorial `fracturing' of the main social and ethnic groups in Israel/Palestine. This has prevented the emergence of effective pressure for regional devolution. Israel's character as a settler and settling state, and its central project of Judaizing contested territories, enabled the Israeli `ethnocracy' and its (mainly Ashkenazi and secular) elites to create a political geography of `fractured ethnic and social regions'. Dispersing minorities and legitimizing segregation and inequality, all in the name of the `national interest', achieved this. The Israeli political landscape is therefore organized as `fractured regions', each representing a distinct and interconnected, yet geographically dispersed, set of localities, and resembling a `chain of beads'. The logic of dispersal and segregation, in turn, has also influenced patterns of development and residential separation within Israel's main urban areas. Thus, ethnic and social fragmentation and conflict, and not a putative process of national or metropolitan integration, can explain much of Israel's highly centralized power structure. 相似文献
109.
干旱、半干旱区域降水趋势可预报期限的初步研究 总被引:1,自引:0,他引:1
应用中国西北和美洲大陆中部干旱、半干旱区域7个长记录站的月降水量记录,分析了降水趋势的可预报期限问题。结果表明:月降水量标准化系数序列的可预报尺度为3个月左右。将该序列进行差分运算后,误差倍增时间会显著加长。 相似文献
110.
着重讨论一种基于灰色GM(1,1)模型及国民收入决定函数模型而建立的新组合模型。该模型建模方法简单,组合性强,并且在各模型的拟合精度提高。该模型汲取了灰色GM(1,1)模型模拟国民收入变化趋势的优点和国民收入决定函数模型模拟国民收入波动的优点,使组合模型不但在趋势上符合国民收入的发展,而且也给出了在波动方面的比较一致的模拟。 相似文献