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A new earthquake catalogue for central, northern and northwestern Europe with unified Mw magnitudes, in part derived from chi-square maximum likelihood regressions, forms the basis for seismic hazard calculations
for the Lower Rhine Embayment. Uncertainties in the various input parameters are introduced, a detailed seismic zonation is
performed and a recently developed technique for maximum expected magnitude estimation is adopted and quantified. Applying
the logic tree algorithm, resulting hazard values with error estimates are obtained as fractile curves (median, 16% and 84%
fractiles and mean) plotted for pga (peak ground acceleration; median values for Cologne 0.7 and 1.2 m/s2 for probabilities of exceedence of 10% and 2%, respectively, in 50 years), 0.4 s (0.8 and 1.5 m/s2) and 1.0 s (0.3 and 0.5 m/s2) pseudoacclerations, and intensity (I0 = 6.5 and 7.2). For the ground motion parameters, rock foundation is assumed. For the area near Cologne and Aachen, maps
show the median and 84% fractile hazard for 2% probability of exceedence in 50 years based on pga (maximum median value about
1.5 m/s2), and 0.4 s (>2 m/s2) and 1.0 s (about 0.8 m/s2) pseudoaccelerations, all for rock. The pga 84% fractile map also has a maximum value above 2 m/s2 and shows similarities with the median map for 0.4 s. In all maps, the maximum values fall within the area 6.2–6.3° E and
50.8–50.9° N, i.e., east of Aachen. 相似文献
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Remeasurements of weathering rates at six sites on the base of the balustrade of St. Paul's Cathedral gave substantially lower mean results (0.06 mm a?1, 1980–1985) than for earlier results (0.14 mm a?1, 1980–1981). Statistical analysis of the data showed that for five of the sites there were no significant differences between the measurement periods. The only significant spatial difference was for the southwest (exposed) site which was greater than the other sites for 1980–1981, but not at later times. This site also showed the only significant decrease over time. If this site is included in the statistical analysis, the whole set shows a significant decrease over time; omitting this site from the data removes any significant differences over time. The results for this one site for 1980–1981 thus have significant bias on the data body as a whole. Methodological problems, such as rock erosion by the probe and temperature effects, are thought to have minimal effect on the interpretation of the data. Calibrations showed that measurements were accurate to ±0.006 mm and that only results of a change ≥ 0.02 mm were reliably interpretable as different. Remeasurements of the Lead Plug Index (LPI) for the top of the balustrade in 1987 gave a mean rate for 1718–1985 of 0.081 mm a?1. This is not significantly different from the 1718–1980 mean rate of 0.078 mm a?1 but the data are not directly comparable, the 1987 sample being smaller than the 1980 set. For the 1987 data, the only statistically significant differences are for the southeast rate ≧ northeast and for a rise in rate in the northeast quadrant. The LPI data are comparable to most of the 1980–1985 MEM data. The conclusion is that most erosion rates have neither increased nor decreased significantly in the measurement time, except for a significant decrease at one (southwest) site from 1980–1981 to 1981–1982. Such a sustained level of erosion gives cause for concern in the context of stone conservation. Causative factors of air quality are discussed and while SO2 levels have decreased, NO2 and smoke levels show increases. An overall decrease in stone decay in association with the decrease in SO2 levels is thus not in evidence. 相似文献
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Historic masonry buildings in seismically active regions are severely damaged by earthquakes, since they certainly have not been explicitly designed by the original builders to withstand seismic effects, at least not in a ‘scientific’ way from today’s point of view. The assessment of their seismic safety is an important first step in planning the appropriate interventions for improving their pertinent resistance. This paper presents a procedure for assessing the seismic safety of historic masonry buildings based on measurements of their natural frequencies and numerical simulations. The modelling of the brittle nonlinear behaviour of masonry is carried out on the macro-level. As an example, a recently completed investigation of the seismic behaviour of the Aachen Cathedral is given, this being the first German cultural monument to be included in the UNESCO cultural heritage list in 1978. Its construction goes back to the 9th century a.d. and it is considered as one of the finest examples of religious architecture in Central Europe. The investigation is based on measurements of the natural frequencies at different positions and numerical simulations using a detailed finite element model of the Cathedral. 相似文献
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It is often necessary to locate the original quarry which supplied the stone for a particular historical building. This stones could be used for future restoration work and for testing in the laboratory (artificial aging tests, physical properties determination, control of the efficacy of conservation treatments, etc.). Generally, reviewing historical documentation gives information about the geographical setting of quarries and location of the stones in the monument, but this information needs to be proved by field and laboratory studies. The comparative study of stone from quarries and monuments should basically include the following: (1) mineralogical and petrographical studies; (2) the chemical analysis of major, minor and trace elements; (3)stable isotopes determinations; (4) physical properties of quarry materials and unweathered building stone (water absorption, ultrasound transmission velocity, porosity and porous system, density, bulk density, compressive strength, etc.). This methodology was applied to Málaga Cathedral stones represented in the main façade, towers, and the western zone of the terrace, which, according to historical literature, came from Almayate (Miocene–Pliocene limestones) and Cerro Coronado (Permotriassic sandstone) in Málaga. The conclusion of the comparative study carried out on quarries and building stones was consistent with the information available from the historical documentation. 相似文献
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S. T. Trudgill H. A. Viles R. Inkpen C. Moses W. Gosling T. Yates P. Collier D. I. Smith R. U. Cooke 《地球表面变化过程与地形》2001,26(10):1129-1142
Microerosion meter (MEM) measurements of the surface height of the balustrade of St Paul's Cathedral, London, have been repeated in the year 2000 following earlier measurements in 1980, 1981, 1985 and 1990. Methodological sources of error mean that while the measurements were made to 0·0001 mm, the data are reliable to two decimal places. There was a reduction in the mean erosion rate on horizontal sites from 0·045 mm a?1 in the period 1980–1990 to 0·025 mm a?1 in 1990–2000. Decreases in atmospheric SO2 levels from 20–25 ppb in 1980–1982 to around 10 ppb in 1990–2000, offer a causal explanation. The surface topography evolved more erratically in 1990–2000 than before, with much, but not all, of the more microelevated areas showing greater, and often more variable erosion. There are also indications of less erosion and more surface rises in low‐lying microareas on horizontal sites which is interpreted as possible deposition and/or microfloral growth in wetter depressions, the pattern being largely absent on a well drained vertical site. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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宗教地理是文化地理重要的研究内容之一,但在中国相关实证研究仍不多见。结合半结构问卷调查和访谈,对广州石室圣心大教堂的非洲裔移民宗教场所地方感特征及其形成机理进行探讨。研究发现：非洲裔移民宗教场所地方依恋和地方认同发展快于地方依赖;非裔移民较强的圣地地方依恋同时存在较强的空间可替代性,但又由于区位等因素存在宗教功能之外的非可替代性;圣地地方依赖则因被宗教教义视为功利性而被掩盖。回归分析表明,社交和场所互动时间是指示地方感的最显著指标。随着非粤宗教文化的融合发展,宏观政治环境以及语言文化隔离等外生因素正对宗教地方感的提高产生重要影响。 相似文献
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