长江三峡工程坝址地震危险性分析

本文在研究三峡地区地震地质环境和地震活动规律的基础上,结合模拟实验研究结果划分了三峡地区潜在震源区。确定出相应的地震活动性参数。并对三峡工程三斗坪坝址进行了地震危险性分析,给出了三斗坪坝址不同期限内的地震影响烈度和峰值地面加速度的超越概率。     

概率地震危险性评价系统开发

工程建设时必须对工程场地的地震危险性进行评价,并且对工程结构物要采取抗震设计。由于相关部门往往针对某一地区只提供一个地震设防加速度范围值或地震设防烈度值,而且某一地震烈度值所对应的加速度值的范围也很大,使得在实际应用中给具体工程安全、经济地选用合适的抗震设防加速度带来一定困难;为解决这个问题,本文以概率地震危险性评价理论为基础,开发了一套地震危险性评价系统。利用该评价系统根据相关地震活动性参数,可以方便、快速地计算出具体工程应该采用的抗震设防加速度值,从而解决了工程活动中安全、经济地选用抗震设防加速度值的问题。文中还针对潜在线源和潜在面源的处理难以在程序上实现这一难题,分别提出了一种精确求解和近似求解的算法。本文并以实例进行了评价计算,计算结果与中国地震局公布的数据符合较好,从而验证了开发的评价系统具有较好的可信度。     

同震滑坡发生概率研究——新一代地震滑坡危险性模型

地震滑坡发生真实概率研究基本空白。本研究创新性的利用贝叶斯概率方法与机器模型开展了中国地震滑坡危险性真实概率研究,制作了第一代中国地震滑坡危险性概率图。基于9个地震案例开展研究,包括1999年台湾集集、2005年克什米尔、2008年汶川、2010年玉树、2013年芦山、2013岷县、2014鲁甸、2015尼泊尔、2017九寨沟地震,这9次地震中7次发生在中国,2005年克什米尔与2015尼泊尔地震均发生在中国邻区,可以更好的控制模型预测精度。这些地震事件均有详细完整的,利用面要素标识的地震滑坡数据,包括306 435处真实的地震滑坡记录。考虑到真实的地震滑坡发生区域,滑坡面积规模的差别,滑坡与不滑样本的比例等因素,共选取了5 117 000个模型训练样本。选择绝对高程、相对高差、坡度、坡向、斜坡曲率、坡位、地形湿度指数、土地覆盖类型、植被覆盖度、与断层距离、地层、年均降水量、地震动峰值加速度共13个地震滑坡影响因子。采用贝叶斯概率方法与机器学习模型相结合,建立地震滑坡发生的多因素影响模型,得到各个连续因子的权重与分类因子的各个分类的权重。再将模型应用到整个中国研究区,地震动峰值加速度因子为触发因子。分别考虑研究区在经历不同地震动峰值加速度（0.1~1 g,每0.1 g一个结果,共10个结果）下的地震滑坡发生真实概率。此外,还结合中国地震动峰值加速度分布图,得到了中国地震动峰值加速度背景下的地震滑坡发生真实概率分布。     

上海市南部地区地震危险性分析

本文通过对工作区内地震地质、地球物理场特征研究,确定了场区周围九个潜在震源区,分析计算得出各潜在震源区的地震活动性参数。用概率论的方法,以洪华生等人提出的《断层—破裂模型》计算得到上海市南部地区地震烈度年超越概率以及10、20、50、100、200、300、500年内场区的地震影响烈度超越概率,并对这一地区的地震危险性进行了估计。     

基于Newmark模型的概率地震滑坡危险性模型参数优化与应用:以鲁甸地震区为例

应用概率地震危险性评价模型进行地震滑坡危险性区划,是解决潜在地震诱发滑坡危险性评价中震源不确定性与诱发滑坡时空不确定性的有效方法 .通过理论分析,结合鲁甸地震区的实际情况,对基于力学原理的Newmark滑块位移模型与概率地震滑坡危险性分析方法中的参数的不确定性问题进行了分析,将斜坡岩土体地震作用下的强度衰减效应、地震加速度地形放大效应、断层破碎带效应融合到了斜坡累积位移计算模型中,进行了模型计算参数的优化.改进后的分析模型,更好地反映了高陡斜坡地形与断层破碎带对地震滑坡灾害发育的控制作用,在鲁甸地震区域滑坡应用中,优化模型中的滑坡失稳极高风险区与实际地震滑坡分布表现出了较好的一致性,在超越概率2%的滑坡失稳概率分布中,鲁甸地区包谷垴-小河断裂、鲁甸-昭通断裂带及牛栏江河谷地带地震滑坡高-极高风险区分布面积增幅十分显著.因此,在Newmark滑块位移模型中考虑地震动参数与岩土参数动态响应规律与变量间的定量关系,对于提高区域斜坡稳定性分析的可靠性具有重要意义.     

某低中放废物处置预选区地震活动性与地震危险性分析

本文分析了某低中放废物处置预选区的地震构造环境和地震活动性,对研究区潜在震源区的划分进行了修正,采用地震危险性概率分析法对该预选区不同超越概率水平的基岩峰值加速度和烈度进行了计算,分析了基岩峰值加速度的空间分布特征,认为预选区基岩峰值加速度分布与潜在震源区密切相关,在此基础上,对处置场的选址提出了建议。     

基于蒙特卡洛模拟的概率断层位错危险性分析

同震位错对川藏铁路等跨断层工程的安全造成严重威胁,合理评价活断层的位错参数具有重要的应用价值.由于传统的确定性评价方法存在无法区分工程场点的重要程度和其在断层上的相对位置等缺陷,越来越多的学者推荐采用概率断层位错危险性分析（PFDHA）.然而基于经典的概率性方法开展PFDHA原理复杂且实现困难,不利于吸收断层地震活动性研究的最新成果,也有碍于PFDHA的普及和推广.相比经典的概率性方法,蒙特卡洛模拟具备逻辑清晰易懂、程序易于实现且兼容性和扩展性好的优点.本研究基于蒙特卡洛模拟实现了概率断层位错危险性分析的一般性算法,并将该方法应用于鲜水河断裂带的炉霍段.结果显示,PFDHA的结果随着超越概率水准或工程场点在断层上的相对位置的不同而显著变化.适当考虑最大同震位错和地表破裂长度的不确定性得到的位错参数更加合理.超越概率大于等于100年2%时,PFDHA的结果显著小于确定性方法的结果.然而随着断层活动性的提高,100年超越概率1%的结果可能会大于确定性方法的结果.按照不同类型工程的抗震设防水准选择相应的PFDHA评价结果,既有利于工程的安全,也有助于大多数工程节约成本.PFDHA相比确定性方法具备多种优势,有望为川藏铁路等重大工程的抗断参数评估提供技术支撑.      

渤海海峡跨海通道工程区地震危险性分析

研究渤海海峡地区区域历史地震时空分布特征,分析渤海海峡地区的地震发生位置及其发震规律,论述历史地震对工程场地的影响,为渤海海峡跨海通道的选址提供依据,使选址时尽量避开活动断层以减少地震对跨海通道的影响,增加评判工程稳定性的因子,使评判结论更加可靠。     

南水北调西线工程区地震危险性分析及预测

作者已在《青藏高原地质过程与环境灾害效应》文集中, 对南水北调西线调水区地震与活动断裂的关系及其特征进行了论述, 本文通过南水北调西线工程区地震活动特点, 利用区域地震资料采用统计的方法研究地震发生的时空分布特点及预测未来发生地震的可能性。      

Seismic Hazard Estimation in Northern Algeria

In the present study, the seismic hazard in northern Algeria is estimated using both physical strain energy release and Gumbel's extreme values approaches. For six of the most industrial and populated cities in Algeria, seismic hazard is assessed and examined in greater detail. Gumbel's extreme values approach has been used to estimate seismic hazard in terms of magnitude and P.G.A at each point of an equispaced grid all over the north of Algeria. An average attenuation relationship for PGA has been provided using known relations which have been established in regions with similar attenuation characteristics.The results are presented mainly in the form of graphs and contour maps of magnitudes (respectively PGA) with a 60% probability of not being exceeded in the next 100 and 200 years. Globally, they give main features of northern Algeria in terms of zoning (as well as in terms of magnitude and in terms of PGA). They corroborate the ones obtained through other works, especially in the basin areas (Mitidja, Cheliff, Soumam and Constantine Basin).     

Seismic Hazard Assessment in Armenia

An evaluation of seismic hazard assessment in the territory of Armenia is presented in this work. The catastrophic M = 7.0 Spitak earthquake in 1988 revealed the drawbacks of the acting seismic zoning map. Two seismic hazard maps have been compiled in NSSP RA during 1991–1996. The deterministic approach was applied in the first one and the probabilistic in the second one. Both maps were compiled on the basis of the same database. Comparison between the maps shows good correlation. This revised version was published online in June 2006 with corrections to the Cover Date.     

A New Probabilistic Seismic Hazard Analysis for the Vrancea (Romania) Seismogenic Zone

In this paper we apply a probabilistic methodology to map specific seismic hazard induced by the Vrancea Seismogenic Zone, which represents the uttermost earthquake danger to Romania as well as its surroundings. The procedure is especially suitable for the estimation of seismic hazard at an individual site, and seismic hazard maps can be created by applying it repeatedly to grid points covering larger areas. It allows the use of earthquake catalogues with incompletely reported historical and complete instrumental parts. When applying themethodology, special attention was given to the effect of hypocentral depth and the variation of attenuation according to azimuth. Hazard maps specifying a 10% chance of exceedance of the given peak ground acceleration value for an exposure time of 50 years were prepared for three different characteristic depths of earthquakes in the Vrancea area. These maps represent a new realistic contribution to the mitigation of the earthquake risk caused by the Vrancea Seismogenic Zone in terms of: (1) input data (consistent, reliable, and the most complete earthquake catalogue), (2) appropriate and specific attenuation relationships (considering both azimuthal and depth effects); and (3) a new and versatile methodology.     

Seismic Hazard of Honduras

In this paper we have described the proceduresused, input data applied and results achieved in ourefforts to develop seismic hazard maps of Honduras.The probabilistic methodology of Cornell is employed.Numerical calculations were carried out by making useof the computer code SEISRISK III. To examine theimpact of uncertainties in seismic and structuralcharacteristics, the logic tree formalism has beenused. We compiled a de-clustered earthquake cataloguefor the region comprising 1919 earthquakes occurringduring the period from 1963 to 1997. Unified momentmagnitudes were introduced. Definition of aseismotectonic model of the whole region under review,based on geologic, tectonic and seismic information,led to the definition of seven seismogenetic zones forwhich seismic characteristics were determined. Fourdifferent attenuation models were considered. Resultsare expressed in a series of maps of expected PGA for60% and 90% probabilities of nonexceedence in a50-year interval which corresponds to return periodsof 100 and 475 years, respectively. The highest PGAvalues of about 0.4g (90% probability ofnon-exceedence) are expected along the borders withGuatemala and El Salvador.     

Spectral-based Probabilistic Seismic Hazard Analysis for Fethiye, Muğla

Fethiye is an important region located in the eastern part of the Mediterranean Basin.This region which is the most active part of the south-western Anatolia ex...     

Probabilistic Analysis of Tsunami Hazards*

Determining the likelihood of a disaster is a key component of any comprehensive hazard assessment. This is particularly true for tsunamis, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models. We discuss probabilistic tsunami hazard analysis (PTHA) from the standpoint of integrating computational methods with empirical analysis of past tsunami runup. PTHA is derived from probabilistic seismic hazard analysis (PSHA), with the main difference being that PTHA must account for far-field sources. The computational methods rely on numerical tsunami propagation models rather than empirical attenuation relationships as in PSHA in determining ground motions. Because a number of source parameters affect local tsunami runup height, PTHA can become complex and computationally intensive. Empirical analysis can function in one of two ways, depending on the length and completeness of the tsunami catalog. For site-specific studies where there is sufficient tsunami runup data available, hazard curves can primarily be derived from empirical analysis, with computational methods used to highlight deficiencies in the tsunami catalog. For region-wide analyses and sites where there are little to no tsunami data, a computationally based method such as Monte Carlo simulation is the primary method to establish tsunami hazards. Two case studies that describe how computational and empirical methods can be integrated are presented for Acapulco, Mexico (site-specific) and the U.S. Pacific Northwest coastline (region-wide analysis). * The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

地震动力学与板块构造:地震灾害评估

作为地震灾害评估的理论基础,地震动力学主要研究与地震活动有关的断裂机制、破裂过程、震源辐射和由此而引起的地震波的传播及地面运动规律。对地震力学、震源辐射和能量释放等经典理论问题进行了系统研究。在此基础上,应用最新的定量地震学研究方法,以逻辑树的形式综合地震、地质和大地测量资料,提供了不同构造环境和断裂机制条件下地震灾害评估的概率分析和确定性分析实例。用于震源分析的典型构造类型包括板内地壳震源层、地壳活动断层及其速率、板块俯冲界面和俯冲板片。由于输入模型中不确定因素的存在,如输入参数的随机性和科学分析方法本身的不确定性,对分析结果的不确定性需审慎对待。通常对不同的模型或参量,包括地面衰减模型,进行加权平均可较为合理地减小结果的偏差：概率分析和确定性分析方法的结合亦为可取之有效途径。     

Seismic Hazard Analysis for the Bangalore Region

Indian peninsular shield, which was once considered to be seismically stable, is experiencing many earthquakes recently. As part of the national level microzonation programme, Department of Science and Technology, Govt. of India has initiated microzonation of greater Bangalore region. The seismic hazard analysis of Bangalore region is carried out as part of this project. The paper presents the determination of maximum credible earthquake (MCE) and generation of synthetic acceleration time history plot for the Bangalore region. MCE has been determined by considering the regional seismotectonic activity in about 350 km radius around Bangalore city. The seismotectonic map has been prepared by considering the faults, lineaments, shear zones in the area and historic earthquake events of more than 150 events. Shortest distance from the Bangalore to the different sources is measured and then peak ground acceleration (PGA) is calculated for the different source and moment magnitude. Maximum credible earthquake found in terms of moment magnitude is 5.1 with PGA value of 0.146 g at city centre with assuming the hypo central distance of 15.88 km from the focal point. Also, correlations for the fault length with historic earthquake in terms of moment magnitude, yields (taking the rupture fault length as 5% of the total fault length) a PGA value of 0.159 g. Acceleration time history (ground motion) and a response acceleration spectrum for the corresponding magnitude has been generated using synthetic earthquake model considering the regional seismotectonic parameters. The maximum spectral acceleration obtained is 0.332 g for predominant period of 0.06 s. The PGA value and synthetic earthquake ground motion data from the identified vulnerable source using seismotectonic map will be useful for the PGA mapping and microzonation of the area.     

地理信息系统在滑坡灾害研究中的应用

对地理信息系统 ( GIS)技术在滑坡研究中的应用现状作了分析 ,并介绍了笔者在该方面的一些研究成果 ,认为只有在数据获取、GIS与滑坡专业模型的集成、GIS与遥感的集成等方面有较大的突破之后 ,才能充分发挥 GIS在滑坡研究中的作用。     

Estimation of Seismic Landslide Hazard in the Eastern Himalayan Syntaxis Region of Tibetan Plateau

The eastern Himalayan syntaxis is one of the most tectonically active and earthquake-prone regions on Earth where earthquake-induced geological disasters occur frequently and caused great damages. With the planning and construction of Sichuan-Tibet highway, Sichuan-Tibet railway and hydropower development on the Yarlung Zangbo River etc. in recent years, it is very important to evaluate the seismic landslide hazard of this region. In this paper, a seismic landslide hazard map is produced based on seismic geological background analysis and field investigation using Newmark method with 10% PGA exceedance probabilities in future 50 years by considering the influence of river erosion, active faults and seismic amplification for the first time. The results show that the areas prone to seismic landslides are distributed on steep slopes along the drainages and the glacier horns as well as ridges on the mountains. The seismic landslide hazard map produced in this study not only predicts the most prone seismic landslide areas in the future 50 years but also provides a reference for mitigation strategies to reduce the exposure of the new building and planning projects to seismic landslides.