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11.
The shear viscosities and 1 bar heat capacities of glasses and melts along the 67mol% silica isopleth in the system SiO2-Al2O3-Na2O-TiO2 have been determined in the temperature ranges 780-1140 K and 305-1090 K respectively. Anomalous behaviour of both these properties is observed for compositions rich in TiO2 and/or Al2O3, an observation attributed to liquid-liquid phase separation followed by anatase crystallization. For samples which do not show anomalous behaviour, it is found that the partial molar heat capacity of the TiO2 component previously determined in Al-free compositions reproduces our heat capacities to within 1.3%. Viscosity data show that addition of TiO2 tends to increase viscosity and melt fragility at constant temperature. Furthermore, heat capacity and viscosity data may be combined within the framework of the Adam-Gibbs theory to extract values of the configurational entropy of the liquids and qualitative estimates of the variation of the average energy barrier to viscous flow. Configurational entropy at 900K is inferred to decrease upon addition of TiO2, in contrast to previous results from Al-free systems. The compositional limit separating normal from anomalous behaviour, as well as the data for homogenous melts have been used to constrain the structural role of Ti in these samples. Our data are consistent with a majority of Ti in five-fold coordination associated with a titanyl bond, in agreement with previous spectroscopic studies. Furthermore, we find no evidence for a Ti-Al interaction in our samples, and we are led to the conclusion that Al and Ti are incompletely mixed, a hypothesis consistent with the observed reduction of configurational entropy upon addition of TiO2, suggesting an important role of medium range order in controlling the variations in thermodynamic properties. 相似文献
12.
The time history of strong ground motion can be synthesized by empirical Green's function (EGF) method.Firstly a large seismic event is discretized into a series of subevents; secondly recordings of earthquakes with proper size and spatial distribution are chosen as time history (EGF) of those subevents; finally the EGFs are summated to get the time history of ground motion caused by the large event. 相似文献
13.
本文总结分析了发生在新丰江水库老震区,距1962年6.1级主震27年的1次4.5级地震的活动和特点,认为此次4.5级地震及其伴生的小震群仍系新丰江水库诱发地震序列的中晚期强余震。 相似文献
14.
本文采用大森公式n(t)=K/(t+c)^p求解K、c、p三个参数,对云南1965年以来71个地震序列进行研究。确定P=0.8为前兆震群和正常震群的判定指标。利用K、c、p三参数计算序列理论曲线得到晚期强余震前差残曲线超出两倍均方差的结果。 相似文献
15.
本文应用动态系统时间连续模型建立的新方法(DM(n,h)模型),通过对唐山老震区ML>4.7级地震的建模,讨论DM(n,h)模型对唐山老震区晚期强余震预测的可行性。并比较了DM(n,h)模型与GM(n,h)模型,发现DM(n,h)模型优于GM(n,h)模型,同时,给出了唐山老震区晚期强余震的预报结果。 相似文献
16.
Yoshinobu Tsuji Fumihiko Imamura Hideo Matsutomi Costas E. Synolakis Puspito T. Nanang Jumadi Satoshi Harada Se Sub Han Ken'ichi Arai Benjamin Cook 《Pure and Applied Geophysics》1995,144(3-4):839-854
A field survey of the June 3, 1994 East Java earthquake tsunami was conducted within three weeks, and the distributions of the seismic intensities, tsunami heights, and human and house damages were surveyed. The seismic intensities on the south coasts of Java and Bali Islands were small for an earthquake with magnitudeM 7.6. The earthquake caused no land damage. About 40 minutes after the main shock, a huge tsunami attacked the coasts, several villages in East Java Province were damaged severely, and 223 persons perished. At Pancer Village about 70 percent of the houses were swept away and 121 persons were killed by the tsunami. The relationship between tsunami heights and distances from the source shows that the Hatori's tsunami magnitude wasm=3, which seems to be larger for the earthquake magnitude. But we should not consider this an extraordinary event because it was pointed out byHatori (1994) that the magnitudes of tsunamis in the Indonesia-Philippine region generally exceed 1–2 grade larger than those of other regions. 相似文献
17.
Herak Marijan Herak Davorka Markušić Snježana Ivančić Ines 《Studia Geophysica et Geodaetica》2001,45(3):251-266
The rate of aftershock occurrence after the M6 Ston-Slano (Croatia) earthquake is modeled as the Epidemic Type Aftershock Sequence (ETAS). Increase of the modeled cumulative number of aftershocks with time was fitted to observations by the least-squares criterion using the combined grid-search and Monte-Carlo approach. This enabled not only the estimation of the most probable ETAS parameters, but also the determination of their confidence limits, as well as the estimation of the bias between them. It has been found that the bias is significant for some of the parameter pairs, regardless of the threshold magnitude assumed. Residual analyses revealed that all strong aftershocks (M
L
4.5) occurred during the periods of normal to high aftershock activity. There were two periods of quiescence in the sequence, both of which were followed by a strong aftershock. 相似文献
18.
地震序列较强余震灰色及最小二乘拟合预测方法的应用研究 总被引:1,自引:0,他引:1
在收集、整理1966年~2002年8月我国(主要为大陆地区)183个5级以上地震序列资料的基础上,应用灰色预测和最小二乘拟合预测方法,对每一地震序列较强(显著)余震发震时间进行“硬性”检验预测。结果表明,2种预测方法对7级以上地震序列和6级地震序列的较强(显著)余震具有较好的预测效能,预测效能分别为76.2%和64.7%;而对5级地震序列预测效果则不甚明显。因此,灰色预测和最小二乘拟合预测方法主要着眼于对大(强)地震的较强(显著)余震预测,可望在地震现场大(强)震应急工作中发挥积极作用。 相似文献
19.
Bridge fragility curves, which express the probability of a bridge reaching a certain damage state for a given ground motion parameter, play an important role in the overall seismic risk assessment of a transportation network. Current analytical methodologies for generating bridge fragility curves do not adequately account for all major contributing bridge components. Studies have shown that for some bridge types, neglecting to account for all of these components can lead to a misrepresentation of the bridges' overall fragilities. In this study, an expanded methodology for the generation of analytical fragility curves for highway bridges is presented. This methodology considers the contribution of the major components of the bridge, such as the columns, bearings and abutments, to its overall bridge system fragility. In particular, this methodology utilizes probability tools to directly estimate the bridge system fragility from the individual component fragilities. This is illustrated using a bridge whose construction and configuration are typical to the Central and Southeastern United States and the results are presented and discussed herein. This study shows that the bridge as a system is more fragile than any one of the individual components. Assuming that the columns represent the entire bridge system can result in errors as large as 50% at higher damage states. This provides support to the assertion that multiple bridge components should be considered in the development of bridge fragility curves. The findings also show that estimation of the bridge fragilities by their first‐order bounds could result in errors of up to 40%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
20.