National-scale data-driven rainfall induced landslide susceptibility mapping for China by accounting for incomplete landslide data     

Qigen Lin  Pedro Lima  Stefan Steger  Thomas Glade  Tong Jiang  Jiahui Zhang  Tianxue Liu  Ying Wang 《地学前缘(英文版)》2021,12(6):262-276

China is one of the countries where landslides caused the most fatalities in the last decades.The threat that landslide disasters pose to people might even be greater in the future,due to climate change and the increasing urbanization of mountainous areas.A reliable national-scale rainfall induced landslide suscep-tibility model is therefore of great relevance in order to identify regions more and less prone to landslid-ing as well as to develop suitable risk mitigating strategies.However,relying on imperfect landslide data is inevitable when modelling landslide susceptibility for such a large research area.The purpose of this study is to investigate the influence of incomplete landslide data on national scale statistical landslide susceptibility modeling for China.In this context,it is aimed to explore the benefit of mixed effects mod-elling to counterbalance associated bias propagations.Six influencing factors including lithology,slope,soil moisture index,mean annual precipitation,land use and geological environment regions were selected based on an initial exploratory data analysis.Three sets of influencing variables were designed to represent different solutions to deal with spatially incomplete landslide information:Set 1(disregards the presence of incomplete landslide information),Set 2(excludes factors related to the incompleteness of landslide data),Set 3(accounts for factors related to the incompleteness via random effects).The vari-able sets were then introduced in a generalized additive model(GAM:Set 1 and Set 2)and a generalized additive mixed effect model(GAMM:Set 3)to establish three national-scale statistical landslide suscep-tibility models:models 1,2 and 3.The models were evaluated using the area under the receiver operating characteristics curve(AUROC)given by spatially explicit and non-spatial cross-validation.The spatial pre-diction pattern produced by the models were also investigated.The results show that the landslide inven-tory incompleteness had a substantial impact on the outcomes of the statistical landslide susceptibility models.The cross-validation results provided evidence that the three established models performed well to predict model-independent landslide information with median AUROCs ranging from 0.8 to 0.9.However,although Model 1 reached the highest AUROCs within non-spatial cross-validation(median of 0.9),it was not associated with the most plausible representation of landslide susceptibility.The Model 1 modelling results were inconsistent with geomorphological process knowledge and reflected a large extent the underlying data bias.The Model 2 susceptibility maps provided a less biased picture of landslide susceptibility.However,a lower predicted likelihood of landslide occurrence still existed in areas known to be underrepresented in terms of landslide data(e.g.,the Kuenlun Mountains in the northern Tibetan Plateau).The non-linear mixed-effects model(Model 3)reduced the impact of these biases best by introducing bias-describing variables as random effects.Among the three models,Model 3 was selected as the best national-scale susceptibility model for China as it produced the most plausible portray of rainfall induced landslide susceptibility and the highest spatially explicit predictive perfor-mance(median AUROC of spatial cross validation 0.84)compared to the other two models(median AUROCs of 0.81 and 0.79,respectively).We conclude that ignoring landslide inventory-based incomplete-ness can entail misleading modelling results and that the application of non-linear mixed-effect models can reduce the propagation of such biases into the final results for very large areas.  相似文献   

Genetic waveform modeling for the crustal structure in Northeast Japan     

《Journal of Asian Earth Sciences》2014

We propose a genetic algorithm (GA) search procedure for waveform modeling of local crustal earthquakes for optimal one-dimensional (1-D) crustal velocity model. Both waveforms and travel-time data are used for the structure determination. The use of travel times in model evaluation improves the waveform modeling performance in the sense of computation speed and accuracy. We applied this method to broadband waveforms of a local crustal earthquake (M 4.2) in Northeast Japan. P-wave velocities of the crustal model are found to be 4.95 ± 0.30, 5.9 ± 0.02, and 6.51 ± 0.20 km/s for a surface layer, upper crust and lower crust, respectively. The surface layer thickness and the Conrad and Moho depths are found to be 3.01 ± 0.8, 17.77 ± 0.4 and 34.59 ± 1.0 km, respectively. For epicentral distances <200 km, our synthetic waveforms match the observed ones generally well. Early arrivals are mainly observed at stations near the Pacific coast in the forearc area having a thinner crust. In contrast, delayed arrivals appear at stations near the volcanic front and back-arc areas where low-velocity anomalies exist due to the effect of the Pacific slab dehydration and the hot upwelling flows in the mantle wedge. In general, our results agree well with the main tectonic setting of the study area, which confirms the reliability of the proposed approach. Despite a 1-D velocity model is too simple to represent the complex crustal structure, it is still required for the conventional routine analysis of seismology, such as earthquake location and source parameter studies. The current approach is considered as a step toward the genetic full waveform modeling for the 3-D velocity model estimation.  相似文献   

标准化降水指数与广义极值分布干旱指数在西北地区应用的对比分析   总被引：4，自引：0，他引：4  

王芝兰  王劲松  李耀辉  王澄海 《高原气象》2013,32(3)

从气象干旱的角度出发,对比分析了基于广义极值分布理论构建的新干旱指数GEVI(Generalized Extreme Value Index)和我国广泛应用的SPI (Standardized Precipitation Index)指数,详细讨论了SPI和GEVI指数在西北地区干旱监测中的适用性.结果表明,SPI和GEVI指数在计算原理上具有相似性,在一定程度上衡量某一地区干旱程度和反映干旱范围方面具有一致性和可替代性.但因两者采取不同的分布形态,对干旱等级的衡量效果不尽相同.GEVI指数在拟合降水量分布函数时更为详尽、客观.在西北5省(区)的干旱监测中,对地处干旱半干旱区的甘肃来说,GEVI指数在于旱强度判定方面优于SPI指数;对年降水量最少的新疆地区来说,GEVI指数比SPI指数在干旱监测方面更为适用.  相似文献   

Numerical assessment of liquefaction mitigation effects on residential houses: Case histories of the 2007 Niigata Chuetsu-offshore earthquake     

《Soil Dynamics and Earthquake Engineering》2013

In this study, the effectiveness of liquefaction countermeasures for residential houses was explored using a fully coupled dynamic effective-stress finite element procedure. Numerical analyses were conducted on two wooden houses that were damaged to different degrees due to dune liquefaction during the 2007 Niigata Chuetsu-offshore earthquake. House A, which was only improved by horizontal drainage pipes to lower the ground water level, was completely destroyed; however, house B, which was improved by a horizontal drainage system, soil–cement mixtures, and steel-pipe piles, was slightly deformed. Numerical results show that the effects of the sand dune slope on the damage to the two houses were somewhat different. For house B, it was found that the steel-pipe piles were more effective. Two countermeasures generally led to a greater degree of reduction in both lateral and vertical displacements of house B than only a single countermeasure employed. In addition, the combined implementation of steel-pipe piles and soil–cement mixtures was the most effective among the cases with two countermeasures.  相似文献   

Effects of sample size on the accuracy of geomorphological models   总被引：1，自引：1，他引：0  

Jan Hjort  Mathieu Marmion 《Geomorphology》2008,102(3-4):341-350

Commonly, the most costly part of geomorphological distribution modelling studies is gathering the data. Thus, guidance for researchers concerning the quantity of field data needed would be extremely practical. This paper scrutinises the relationship between the sample size (the number of observations varied from 20 to 600) and the predictive ability of the generalized linear model (GLM), generalized additive model (GAM), generalized boosting method (GBM) and artificial neural network (ANN) in two data settings, i.e., independent and split-sample approaches. The study was performed using empirical data of periglacial processes from an area of 600 km² in northernmost Finland at grid resolutions of 1 ha (100 × 100 m) and 25 ha (500 × 500 m). A rather sharp increase in the predictive ability of the models was observed when the number of observations increased from 20 to 100, and the level of robust predictions was reached with 200 observations. The result indicates that no more than a few hundred observations are needed in geomorphological distribution modelling at a medium scale resolution (ca. 0.01–1 km²).  相似文献   

时频域油气储层低频阴影检测   总被引：27，自引：8，他引：19       下载免费PDF全文

陈学华  贺振华  黄德济  文晓涛 《地球物理学报》2009,52(1):215-221

为了准确刻画地震信号的局部层次结构,实现高效率的三维地震资料瞬时谱分解,检测油气储层的低频阴影,构造了广义S变换.广义S变换通过引入两个参数,改造S变换的小波函数,使其小波能根据信号处理的具体应用需要而调整.模型信号的仿真发现,广义S变换具有更加优越和灵活可调的时频聚集性能.文中分析了低频阴影的机理,并利用广义S变换对三维实际地震资料进行了瞬时谱分解,它不仅能检测油气储层的低频阴影,而且可以刻画油气储层的岩性边界和空间展布,减小油气储层检测的多解性.  相似文献   

三维层状孔隙介质中弹性波的一种积分表达式I：理论   总被引：1，自引：1，他引：0       下载免费PDF全文

李娜  任恒鑫  黄清华  陈晓非 《地球物理学报》2014,57(6):1891-1899

孔隙介质弹性波传播理论在地球物理勘探、地震工程和岩土动力学等领域有着广泛的应用.而孔隙介质中的弹性波受孔隙度、渗透率、流体黏滞系数等参数的影响,因此研究波场的传播特征将有助于分析和提取这些信息.本文在Biot理论的基础上,针对三维层状孔隙介质模型,利用在合成理论地震图的研究中已经被证实具有稳定、高效且适用范围较广的Luco-Apsel-Chen（LAC）广义反透射方法,给出了弹性波场的一种积分形式的半解析解,可通过数值方法高效、准确地计算层状孔隙介质中的理论波场,所以该积分形式的半解析解可为三维层状孔隙介质波场传播特征的理论数值模拟研究提供一种新的途径和手段.  相似文献   

Generalized cyclic p–y curve modeling for analysis of laterally loaded piles     

《Soil Dynamics and Earthquake Engineering》2014

Owing to their simplicity and reasonable accuracy, Beam on Nonlinear Winkler Foundation (BNWF) models are widely used for the analysis of laterally loaded piles. Their main drawback is idealizing the soil continuum with discrete uncoupled springs representing the soil reactions to pile movement. Static p–y curves, obtained from limited full-scaled field tests, are generally used as a backbone curve of the model. However, these empirically derived p–y curves could not incorporate the effects of various pile properties and soil continuity. The strain wedge method (SWM) has been improved to assess the nonlinear p–y curve response of laterally loaded piles based on a three-dimensional soil–pile interaction through a passive wedge developed in front of the pile. In this paper, the SWM based p–y curve is implemented as the backbone curves of developed BNWF model to study the nonlinear response of single pile under cyclic lateral loading. The developed nonlinear model is capable of accounting for various important soil–pile interaction response features such as soil and pile yielding, cyclic degradation of soil stiffness and strength under generalized loading, soil–pile gap formation with soil cave-in and recompression, and energy dissipation. Some experimental tests are studied to verify the BNWF model and examine the effect of each factor on the response of laterally loaded pile embedded in sand and clay. The experimental data and computed results agree well, confirming the model ability to predict the response of piles under one-way and two-way cyclic loading. The results show that the developed model can satisfactorily simulate the pile stiffness hardening due to soil cave in and sand densification as observed in the experiment. It is also concluded from the results that the gap formation and soil degradation have significant effects on the increase of lateral pile-head deflection and maximum bending moment of the pile in cohesive soils.  相似文献   

四川盆地短历时强降水极值分布的研究   总被引：8，自引：1，他引：7  

司波  余锦华  丁裕国 《气象科学》2012,32(4):403-410

运用广义帕雷托分布(GPD)和广义极值分布(GEV),借助于L-矩的参数估计方法,对四川盆地12站的小时极端降水量进行拟合,并对两种模型的拟合效果进行比较。运用Hill图,结合统计量D*来确定GPD的最佳门限值是合适的,选出的样本是独立的。各站的小时极端降水概率分布均符合GPD和GEV,但GPD模型的拟合精度要优于GEV模型。利用两种模型推算出各站给定重现期的最大小时降水量,其中泸州50 a一遇和100 a一遇的降水极值分位数都超过了100 mm,除了遂宁站外,两种模型估计出的极值分位数的相对误差基本都在10%以下。通过分析,GPD推算的结果更加可靠。  相似文献   

大型工程气候可行性论证中的空间分析方法与应用     

黄世成  程婷  陈兵  周嘉陵 《辽宁气象》2012,(4):90-95

当前大型工程项目的气候可行性论证需要更加精细的评估结论,以满足工程规划、设计和运营等气象防灾减灾的需要。利用1∶25万基础地理信息资料和气象部门在沿湖、沿江、沿海和内陆地区多个大型桥梁工程、核电工程、风电工程等大型工程项目气候可行性论证工作中积累的工程短期气象观测资料和邻近气象站同期同步观测资料、历史气候资料,探讨大型工程气候可行性论证的工程区气候要素极值计算方法和有效的空间插值计算方案,初步建立了基于空间信息分析方法的工程气候可行性论证和系统流程。实际应用表明：采用空间趋势面分析和空间相关分析、空间回归等分析手段的工程气候论证,考虑了项目周边地区气象要素的空间相关性和地形下垫面状况等地理信息,并且具有比常规论证手段更高的计算分辨率,在结合广义极值分析方法后,可以满足大型工程对气象评价的精细化需求。  相似文献