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141.
Landslide hazard and risk assessment on the northern slope of Mt. Changbai, a well-known tourist attraction near the North Korean-Chinese border, are assessed. This study is divided into two parts, namely, landslide hazard zonation and risk assessment. The 1992 Anbalagan and Singh method of landslide hazard zonation (LHZ) was modified and used in this area. In this way, an Associative Analysis Method was used in representative areas to get a measure for controlling factors (slope gradient, relative relief, vegetation, geology, discontinuity development, weak layer thickness and ground water). For the membership degree of factor to slope failure, the middle range of limited values was used to calculate LHZ. Based on an estimation of the potential damage from slope failure, a reasonable risk assessment map was obtained using the relationship of potential damage and probable hazard to aid future planning and prediction and to avert loss of life. 相似文献
142.
Identification, prediction, and mitigation of sinkhole hazards in evaporite karst areas 总被引:1,自引:0,他引:1
Sinkholes usually have a higher probability of occurrence and a greater genetic diversity in evaporite terrains than in carbonate
karst areas. This is because evaporites have a higher solubility and, commonly, a lower mechanical strength. Subsidence damage
resulting from evaporite dissolution generates substantial losses throughout the world, but the causes are only well understood
in a few areas. To deal with these hazards, a phased approach is needed for sinkhole identification, investigation, prediction,
and mitigation. Identification techniques include field surveys and geomorphological mapping combined with accounts from local
people and historical sources. Detailed sinkhole maps can be constructed from sequential historical maps, recent topographical
maps, and digital elevation models (DEMs) complemented with building-damage surveying, remote sensing, and high-resolution
geodetic surveys. On a more detailed level, information from exposed paleosubsidence features (paleokarst), speleological
explorations, geophysical investigations, trenching, dating techniques, and boreholes may help in investigating dissolution
and subsidence features. Information on the hydrogeological pathways including caves, springs, and swallow holes are particularly
important especially when corroborated by tracer tests. These diverse data sources make a valuable database—the karst inventory.
From this dataset, sinkhole susceptibility zonations (relative probability) may be produced based on the spatial distribution
of the features and good knowledge of the local geology. Sinkhole distribution can be investigated by spatial distribution
analysis techniques including studies of preferential elongation, alignment, and nearest neighbor analysis. More objective
susceptibility models may be obtained by analyzing the statistical relationships between the known sinkholes and the conditioning
factors. Chronological information on sinkhole formation is required to estimate the probability of occurrence of sinkholes
(number of sinkholes/km2 year). Such spatial and temporal predictions, frequently derived from limited records and based on the assumption that past
sinkhole activity may be extrapolated to the future, are non-corroborated hypotheses. Validation methods allow us to assess
the predictive capability of the susceptibility maps and to transform them into probability maps. Avoiding the most hazardous
areas by preventive planning is the safest strategy for development in sinkhole-prone areas. Corrective measures could be
applied to reduce the dissolution activity and subsidence processes. A more practical solution for safe development is to
reduce the vulnerability of the structures by using subsidence-proof designs. 相似文献
143.
Hazard-consistent response spectra in the Region of Murcia (Southeast Spain): comparison to earthquake-resistant provisions 总被引:1,自引:1,他引:0
Jorge M. Gaspar-Escribano Belén Benito Julián García-Mayordomo 《Bulletin of Earthquake Engineering》2008,6(2):179-196
Hazard-consistent ground-motion characterisations of three representative sites located in the Region of Murcia (southeast
Spain) are presented. This is the area where the last three damaging events in Spain occurred and there is a significant amount
of data for comparing them with seismic hazard estimates and earthquake-resistant provisions. Results of a probabilistic seismic
hazard analysis are used to derive uniform hazard spectra (UHS) for the 475-year return period, on rock and soil conditions.
Hazard deaggregation shows that the largest hazard contributions are due to small, local events for short-period target motions
and to moderate, more distant events for long-period target motions. For each target motion and site considered, the associated
specific response spectra (SRS) are obtained. It is shown that the combination of two SRS, for short- and long-period ground
motions respectively, provides a good approximation to the UHS at each site. The UHS are compared to design response spectra
contained in current Spanish and European seismic codes for the 475-year return period. For the three sites analysed, only
the Eurocode 8 (EC8) type 2 spectrum captures the basic shape of the UHS (and not the EC8 type 1, as could be expected a priori).
An alternative response spectrum, anchored at short- and long-period accelerations, is tested, providing a close match to
the UHS spectra at the three sites. Results underline the important contribution of the frequent, low-to-moderate earthquakes
that characterize the seismicity of this area to seismic hazard (at the 475-year return period). 相似文献
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147.
Society requires increasingly that the hazard and risk associated with engineered constructions be quantified. The current paper presents geotechnical hazard assessment in the context of a risk framework. Concepts of uncertainties, reliability, safety and risk are briefly reviewed. The use of the approach is exemplified for offshore facilities, including piled foundations, jack-up structures, gravity foundations and underwater slopes. The applications demonstrate that probabilistic analyses complement the conventional deterministic safety factor and deformation-based analyses, and contribute to achieving a safe and optimum design. The probabilistic approach adds value to the results with a modest additional effort. The conclusions emphasize the usefulness of a risk assessment, the importance of engineering judgement in the assessment and the need for involving multi-disciplinary competences to achieve reliable estimates of hazard and risk. The profession can only gain by implementing probabilistic-based thinking and risk-based approaches more systematically than before. 相似文献
148.
Economic damage from natural hazards can sometimes be prevented and always mitigated. However, private individuals tend to underinvest in such measures due to problems of collective action, information asymmetry and myopic behavior. Governments, which can in principle correct these market failures, themselves face incentives to underinvest in costly disaster prevention policies and damage mitigation regulations. Yet, disaster damage varies greatly across countries. We argue that rational actors will invest more in trying to prevent and mitigate damage the larger a country's propensity to experience frequent and strong natural hazards. Accordingly, economic loss from an actually occurring disaster will be smaller the larger a country's disaster propensity – holding everything else equal, such as hazard magnitude, the country's total wealth and per capita income. At the same time, damage is not entirely preventable and smaller losses tend to be random. Disaster propensity will therefore have a larger marginal effect on larger predicted damages than on smaller ones. We employ quantile regression analysis in a global sample to test these predictions, focusing on the three disaster types causing the vast majority of damage worldwide: earthquakes, floods and tropical cyclones. 相似文献
149.
Assessment of secondary mountain hazards along a section of the Dujiangyan-Wenchuan highway 总被引:2,自引:1,他引:1
HAN Yong-shun DONG Shao-kun CHEN Zheng-chao HU Kai-heng SU Feng-huan HUANG Peng 《山地科学学报》2014,11(1):51-65
Conducting a hazard assessment for secondary mountain hazards is the technical basis for reconstructing destroyed highways and for disaster prevention.It is necessary to consider the role and influence of structural engineering measures as an important assessment factor.In this study,based on six substantial field investigations conducted between July 2008 and July 2012,a 2 km wide zone along both sides of the Dujiangyan Wenchuan(Du Wen) Highway was selected as the study area.Microgeomorphic units and small watersheds in the study area were extracted with GIS software and used as basic assessment units.Through field investigations,remote sensing surveys and experimental analysis,a structural engineering effectiveness assessment was conducted using the technique of principal component analysis.The results showed the following:1) A total of 491 collapses,12 landslides,32 slope debris flows and 17 gully debris flows were scatted across the study area.The total overall areal density of all mountain hazards was 25.7%.The distribution of secondary hazards was influenced mainly by seismic intensity,active fault zones,lithology,slope and altitude.More than 70% of secondary hazards occurred in zones with a seismic intensity of XI,a distance to the fault zone of between 0 and 25 km,a slope between 25° and 50°,and an altitude of between 1,000 m and 1,800 m.2) Different structural engineering measures play different roles and effects in controlling different types and scales of secondary mountain hazards.3) With a secondary mountain hazard area of 128.1 km2and an areal density of 34.9%,medium,high and very high hazard zones accounted for 74% of the study area and were located on the high,steep slopes along both sides of the highway.The low hazard zone was located mainly in the valley floor,on gentle slope platforms and at locations 1.5 km away from the highway the hazard area was 45 km2and the areal density was 3.3%.4) The methodology for hazard assessment of secondary mountain hazards,which is based on five factors,solves such key technical problems as the selection of assessment units,multi-source data fusion,and the weight calculation for each assessment index.This study provides a new and more effective method for assessing secondary mountain hazards along highways,and the proposed models fit well with validation data and field observations.The findings were applied to reconstruction and disaster mitigation in the case of the Du Wen Highway and proved to be feasible. 相似文献
150.
M. Coulibaly 《国际地球制图》2013,28(3):217-234
The geographical distribution of a flash flood's occurrence could be an important consideration in assessing its severity and social impacts. In this study, the spatial distribution of survey responses is analysed with respect to features such as the stream network (natural water path), the drainage network, buildings, and catchments. This provides information on both flash flood distribution causes in an urban setting and residents' perceptions of the hazard that would otherwise not be revealed. The study demonstrated the possibility of taking into account people's experience in detecting the location of potential flash flood hazards. It also illustrates the usefulness of GIS-supported spatial analysis of survey results in identifying factors that increase the occurrence of urban flash floods. 相似文献