Probabilistic methodology for the analysis of paleoliquefaction features     

Adrian Rodriguez-Marek  Daniel Ciani   《Engineering Geology》2008,96(3-4):159-172

Paleoliquefaction features can be used to estimate lower bounds on the magnitude and ground motion associated with the earthquake that caused the liquefaction feature. The engineering back-analysis of paleoliquefaction features is usually conducted using state of the practice liquefaction-triggering analysis methodologies. Recent studies have shown that these methodologies are associated with variable probabilities of liquefaction depending on the soil parameters. This would imply that estimates of magnitude and ground motion intensity obtained from these methodologies would not be consistent for all soil sites. Moreover, these estimates could be unconservative. In this paper, the use of a probabilistic methodology for the back-analysis of paleoliquefaction features is proposed. The proposed methodology permits the incorporation of model and parameter uncertainty into the analysis and results in more robust estimates of past magnitude and a measure of the uncertainty associated with these predictions. Previously published paleoliquefaction data are used to demonstrate the applicability of the proposed method. Magnitude estimates obtained with the proposed method do not differ significantly from those obtained using deterministic methodologies, but the proposed methodology permits a quantification of the uncertainty associated with magnitude estimates.  相似文献   

基于GIS的建筑物地震保险损失评估研究     

吕红山  赵凤新  胡聿贤 《震灾防御技术》2006,1(3):273-277

本文讨论了与我国大陆火山地区相关的主要火山灾害类型,即火山空降物、火山碎屑流、火山泥石流、火山熔岩穹与熔岩流的成灾机制和灾害效应,并回顾了国际上火山灾害区划的研究现状,在此基础上,提出了适合我国具体情况的具有概率含义的火山灾害区划图的编图思路。  相似文献   

Shaking hazard compatible methodology for probabilistic assessment of permanent ground displacement across earthquake faults   总被引：2，自引：0，他引：2  

M.I. Todorovska  M.D. Trifunac  V.W. Lee 《Soil Dynamics and Earthquake Engineering》2007,27(6):586-597

A methodology for probabilistic hazard assessment of permanent displacement across faults caused by earthquake rupture is presented, compatible with region specific models for ground shaking hazard in California, developed earlier by the authors and coworkers. Assessment of permanent dislocations across faults is important for the design and retrofit of highway bridges and tunnels crossing faults, as well as for other lifelines crossing faults, such as aqueducts, water and gas lines, etc. The methodology is illustrated for two strike-slip faults (prototypes of Class A and Class B faults in California), for 50 years exposure. The illustrations show that, for given seismic moment rate, the hazard estimates are quite sensitive to how the seismic moment is distributed over earthquake magnitudes. They also show that the hazard is small even for very small levels of displacement, in contrast to ground shaking hazard, which is due to the fact that only one fault contributes to the hazard and not every event on that fault necessarily affects the site.  相似文献   

PSHA: is it science?   总被引：3，自引：0，他引：3  

Heriberta Castaos  Cinna Lomnitz 《Engineering Geology》2002,66(3-4):315-317

Probabilistic seismic hazard analysis (PSHA) is beginning to be seen as unreliable. The problem with PSHA is that its data are inadequate and its logic is defective. Much more reliable, and more scientific, are deterministic procedures, especially when coupled with engineering judgment.  相似文献   

GIS空间数据采集中概率松弛与神经网络的组合模型     

张永生 《测绘学院学报》1994,(4)

本文介绍一种ＧＩＳ空间数据采集中概率松弛与神经网络的组合模型，该模型用于地图分色和立体影像的整体匹配。  相似文献   

Spatial risk analysis of Li-shan landslide in Taiwan   总被引：3，自引：0，他引：3  

Keh-Jian Shou  Ying-Liang Chen 《Engineering Geology》2005,80(3-4):199-213

By coupling limit equilibrium analysis and Monte Carlo analysis with a geography information system (GIS), this study implements a method that can evaluate the risk (corresponding to probability of failure in this study) of landslide with consideration of spatial uncertainties. The GIS can adopt the three-dimensional information including surface topography, underground geomaterial distribution and groundwater level to determine slope profiles for analysis. Then the safety of defined slope can be evaluated by limit equilibrium analysis. In this study, the mechanical properties of geomaterial were considered as random variables instead of single values. The slope and groundwater profiles are also randomly adopted. Through a Monte Carlo sampling process, a distribution of safety factor and probability of failure can be determined. This probabilistic risk analysis approach was applied to Li-shan landslide in Central Taiwan.

Due to heavy rains, the sites near the highway 7A (mileage 73 k + 150) and the highway 8 (mileage 82 k) in the Li-shan Township began to subside in mid April 1990. Topography, geology, and groundwater condition of this area were first reviewed. Based on this review, together with field investigations and a series of limit equilibrium back analyses, a general hypothetic model was established to illustrate the failure mechanism of this landslide area. Then the developed probabilistic risk analysis model is applied to spatially evaluate the risk of this landslide area as well as the performance of the remediation treatment.  相似文献   

On the applicability of neural networks for soil dynamic amplification analysis     

J. E. Hurtado  J. M. Londoo  M. A. Meza 《Soil Dynamics and Earthquake Engineering》2001,21(7):6381

Artificial Neural Networks (ANN) have gained a solid status as a tool for modeling complex phenomena in different areas of research and engineering practice. In this paper, their applicability to estimate the mapping of seismic acceleration from bedrock to free surface in a complex soil profile is explored. Such a use is intended to serve as a hypothesis-free alternative to the dynamic amplification analysis, which is currently based on geophysical and soil dynamics procedures. Were the neural networks to be useful to such a mapping, they could in principle be employed for several purposes, such as soil identification using instrumental data, design of early warning systems and estimation of probabilistic spectra via Monte Carlo simulation, in which the ANN act as an efficient solver surrogate. The conditions under which these ambitious purposes can be reached are discussed. Two classes of multi-layer perceptrons were tested, which are characterized by time-independent and time-dependent connections. It is shown that the first class of networks is useful for response spectrum mapping, while the second performs very well in the assessment of free-surface time series. It arises as the main conclusion that the most promising perspective of application of ANN in this respect is for the estimation of probabilistic free-surface spectra, which is an important goal for the modern trend of reliability-based aseismic design. The limitations to the other said applications are also highlighted.  相似文献   

地震发生概率模型多参数组检验研究     

龚平 《地震研究》2002,25(3):267-274

在地震活动性参数估计中，对同一地区具有相同地震资料和相同的统计方法情况，关于活动性参数会出现因人而异的估计结果。如何这些参数的不同估计做出评价？对此，从统计角度将似然比检验引入到地震活动参数的不同估计的选优排序决策中，分析了似然比检验的基本特征，并以华北地区为例示范性地分析似然比检验对地震活动性参数的决策性检验。  相似文献   

Sensitivity of PSHA results to ground motion prediction relations and logic-tree weights   总被引：7，自引：0，他引：7  

Fabio Sabetta  Antonio Lucantoni  Hilmar Bungum  Julian J. Bommer 《Soil Dynamics and Earthquake Engineering》2005,25(4):317-329

Epistemic uncertainty in ground motion prediction relations is recognized as an important factor to be considered in probabilistic seismic hazard analysis (PSHA), together with the aleatory variability that is incorporated directly into the hazard calculations through integration across the log-normal scatter in the ground motion relations. The epistemic uncertainty, which is revealed by the differences in median values of ground motion parameters obtained from relations derived for different regions, is accounted for by the inclusion of two or more ground motion prediction relations in a logic-tree formalism. The sensitivity of the hazard results to the relative weights assigned to the branches of the logic-tree, is explored through hazard analyses for two sites in Europe, in areas of high and moderate seismicity, respectively. The analyses reveal a strong influence of the ground motion models on the results of PSHA, particularly for low annual exceedance frequencies (long return periods) and higher confidence levels. The results also show, however, that as soon as four or more relations are included in the logic-tree, the relative weights, unless strongly biased towards one or two relations, do not significantly affect the hazard. The selection of appropriate prediction relations to include in the analysis, therefore, has a greater impact than the expert judgment applied in assigning relative weights to the branches of the logic-tree.  相似文献   

An estimate of probabilistic seismic hazard for five cities in Greece by using the parametric-historic procedure     

Pivi Mntyniemi  Theodoros M. Tsapanos  Andrzej Kijko 《Engineering Geology》2004,72(3-4):217-231

A probabilistic procedure was applied to assess seismic hazard for the sites of five Greek cities (Athens, Heraklion, Patras, Thessaloniki and Volos) using peak ground acceleration as the hazard parameter. The methodology allows the use of either historical or instrumental data, or a combination of both. It has been developed specifically for the estimation of seismic hazard at a given site and does not require any specification of seismic sources or/and seismic zones. A new relation for the attenuation of peak ground acceleration was employed for the shallow seismicity in Greece. The computations involved the area- and site-specific parts. When assessing magnitude recurrence for the areas surrounding the five cities, the maximum magnitude, m_max, was estimated using a recently derived equation. The site-specific results were expressed as probabilities that a given peak ground acceleration value will be exceeded at least once during a time interval of 1, 50 and 100 years at the sites of the cities. They were based on the maximum peak ground acceleration values computed by assuming the occurrence of the strongest possible earthquake (of magnitude m_max) at a very short distance from the site and using the mean value obtained with the help of the attenuation law. This gave 0.24 g for Athens, 0.53 g for Heraklion (shallow) and 0.39 g Heraklion (intermediate-depth seismicity), 0.30 g for Patras, 0.35 g for Thessaloniki and 0.30 g for Volos. In addition, the probabilities of exceedance of the estimated maximum peak ground acceleration values were calculated for the sites. The standard deviation of the new Greek attenuation law demonstrates the uncertainty and large variation of predicted peak ground acceleration values.  相似文献