Probabilistic Seismic Hazard Assessment for Iraq Using Complete Earthquake Catalogue Files

Probabilistic seismic hazard analysis (PSHA) has been carried out for Iraq. The earthquake catalogue used in the present study covers an area between latitude 29°–38.5° N and longitude 39°–50° E containing more than a thousand events for the period 1905–2000. The entire Iraq region has been divided into thirteen seismogenic sources based on their seismic characteristics, geological setting and tectonic framework. The completeness of the seismicity catalogue has been checked using the method proposed by Stepp (1972). The analysis of completeness shows that the earthquake catalogue is not complete below M_s=4.8 for all of Iraq and seismic source zones S1, S4, S5, and S8, while it varies for the other seismic zones. A statistical treatment of completeness of the data file was carried out in each of the magnitude classes. The Frequency Magnitude Distributions (FMD) for the study area including all seismic source zones were established and the minimum magnitude of complete reporting (M_c) were then estimated. For the entire Iraq the M_c was estimated to be about M_s=4.0 while S11 shows the lowest M_c to be about M_s=3.5 and the highest M_c of about M_s=4.2 was observed for S4. The earthquake activity parameters (activity rate , b value, maximum regional magnitude m_max) as well as the mean return period (R) with a certain lower magnitude m_min m along with their probability of occurrence have been determined for all thirteen seismic source zones of Iraq. The maximum regional magnitude m_max was estimated as 7.87 ± 0.86 for entire Iraq. The return period for magnitude 6.0 is largest for source zone S3 which is estimated to be 705 years while the smallest value is estimated as 9.9 years for all of Iraq.The large variation of the b parameter and the hazard level from zone to zone reflects crustal heterogeneity and the high seismotectonic complexity. The seismic hazard near the source boundaries is directly and strongly affected by the change in the delineation of these boundaries. The forces, through which the geological structure along the plate boundary in Eastern and Northeastern Iraq are evolved, are still active causing stress-strain accumulation, deformation and in turn producing higher probabilities of earthquake activity. Thus, relatively large destructive earthquakes are expected in this region. The study is intended to serve as a reference for more advanced approaches and to pave the path for the probabilistic assessment of seismic hazard in this region.     

预防原则在地震危险性分析中的应用

在环境领域 ,近来提倡将预防原则作为决策的指导原则。然而 ,关于预防原则的陈述却是各不相同的 ,所以本文的首要任务是对之提出一个令人满意的定义。起因是 1 998年在威斯康星拉辛召开的 Winspread大会的公告。该公告的中心意思是 :“当某种活动增加了有损人类健康或环境的可能性时 ,即使不能从科学上完全确定其因果关系 ,也应采取预防措施。从这个意义上说 ,活动的倡导者而不是大众应承担起验证的责任。”在此 ,我想重申一下地震危险性分析中的预防原则 :“凡是有可能发生危害人类安全和建筑环境 ( builtenvironment)的地震的地方 ,都应…     

地震诱发崩塌滑坡危险区初步预测

地震崩塌滑坡是地震破坏的主要形式之一，在以往国内外中强地震中均有发生，地震崩塌滑坡给社会经济、人民的生命财产带来巨大的破坏和损伤。表1列出了我国近年来发生的几次重大地震崩塌滑坡灾害。     

地震损失概率预测研究中的地震危险性分析方法探讨

本文基于假定未来某段时间内研究地区或场地上地震烈度影响事件遵从贝努利(Bernoulli)随机独立试验过程，利用历史地震烈度-额度统计关系，提出了一种适用于地震损失概率预测的危险性分析方法。     

1 地震灾害及地震预报

1.1 地震灾害 地球上每年要发生上百万次地震,人们可感觉到3级以上的地震就有5万多次,全球平均每年发生5级以上具有破坏性的地震上千次,其中破坏性极大的7级以上地震就有20次之多.这些地震大部分发生在海上,虽然每年发生在大陆上的地震仅占全球地震总数的15%,但给人类造成的损失却占全球地震造成损失的85%.     

基于历史地震史料记载的地震危险性分析方法

现行的地震危险性分析方法是经过潜在震源区划分、地震活动性参数和衰减关系的确定,以及基岩地震动参数的计算而作为基础资料的历史强震目录,同时也是通过历史地震记载的分析得到的。然而,在其每一个环节都存在不确定性,而现有的不确定校正很难达到满意的程度。本文设想仅仅利用历史地震的史料记载,依据最大似然法,计算场地的各不同年份不同超越概率的地震危险性。以怀来、河间、唐山、承德、宁晋、石家庄为例,并仅仅以这些场地的历史记载为依据,不考虑推测的影响烈度,计算这些场地的危险性分析结果,并与中国地震烈度区划图（1990）的结果进行比较,由此来说明本方法具有一定的可利用性。     

姚安6.0级地震的震害指数和烈度

阐述了姚安6.0级地震烈度评定的过程,对各评估区的房屋的破坏比进行了调查,计算出各类房屋的震害指数,进而确定了各评估区的震害指数,并按照<中国地震烈度表>新规定,对各个评估区的烈度作了评定.     

大陆强震危险区可拓方法综合预测应用研究

可拓学始于研究问题的不相容性，本文将它引进地震综合预报当中。通过建立强震危险区可拓方法综合预测模型，计算各类区域指标的关联函数，对华北地区、南北地震带进行全时空、有限时空扫描的应用检验，研究孕震区地震活动图像的演化特征，探索对强震危险区进行综合预测的新途径。初步结果说明该方法在对强震危险区的综合预测中有较好的应用前景。     

Probabilistic Seismic Hazard Assessment for Japan

A probabilistic seismic hazard assessment was performed for the Japanese islands and surrounding areas. Seismic hazard parameters characteristic of the seismic history of the regions were obtained. The probability of occurrence of a large M ≥ 7 earthquake within a 10- and 50-year period was also calculated. Regions of very high levels of hazard occur where the Pacific, Phillipine and Eurasian Plates meet. High probabilities of occurrence of a large M ≥ 7 earthquake within a 10- and 50-year period occur within the region where the Pacific Plate subducts with the Eurasian Plate.     

GIS支持下的地震诱发滑坡危险区预测研究

为了满足对地震诱发滑坡危险区预测的不断增长的迫切要求，灾害评价成为帮助决策过程重要的基础工具之一。即使地震滑坡危险性各组份的评价很困难，但地理信息可辅助提出这种灾害制图的有关方法。描述了用于地理信息系统识别和定量计算不同地震滑坡危险区的技术方法，确定了地震烈度、地形坡度、岩土体类型和现存滑坡密度共4个因子参与的地震诱发滑坡危险性分析。在ARC／INFO DRID支持下，进行叠合分析，由此编制了云南省地震诱发滑坡危险区预测图。由地貌学家提出的地震诱发滑坡预测为规划和工程师提供了对区域规划和建筑工程有价值的技术方法。     

历史有感地震目录及其在地震预报和安全性评价中的应用

历史有感地震是指M=3．5—4．5的历史地震，这些地震都是有感地震，从而在历史文献中都有一个场所以上的记载。我们在1994年已经编辑完成了中国历史有感地震目录，共编入历史有感地震8556条，最早的地震是公元前618年山东曲阜的一次有感地震。其中     

Seismic Hazard Assessment: Issues and Alternatives

Seismic hazard and risk are two very important concepts in engineering design and other policy considerations. Although seismic hazard and risk have often been used interchangeably, they are fundamentally different. Furthermore, seismic risk is more important in engineering design and other policy considerations. Seismic hazard assessment is an effort by earth scientists to quantify seismic hazard and its associated uncertainty in time and space and to provide seismic hazard estimates for seismic risk assessment and other applications. Although seismic hazard assessment is more a scientific issue, it deserves special attention because of its significant implication to society. Two approaches, probabilistic seismic hazard analysis (PSHA) and deterministic seismic hazard analysis (DSHA), are commonly used for seismic hazard assessment. Although PSHA has been proclaimed as the best approach for seismic hazard assessment, it is scientifically flawed (i.e., the physics and mathematics that PSHA is based on are not valid). Use of PSHA could lead to either unsafe or overly conservative engineering design or public policy, each of which has dire consequences to society. On the other hand, DSHA is a viable approach for seismic hazard assessment even though it has been labeled as unreliable. The biggest drawback of DSHA is that the temporal characteristics (i.e., earthquake frequency of occurrence and the associated uncertainty) are often neglected. An alternative, seismic hazard analysis (SHA), utilizes earthquake science and statistics directly and provides a seismic hazard estimate that can be readily used for seismic risk assessment and other applications.     

印度尼西亚日惹地震灾害及其特征

通过对2006年5月27日印度尼西亚日惹6.4级地震灾情调查和评估,得出此次地震灾情分布具有以下特征:(1)尽管日惹地震震级较小,但形成的灾害却很严重,地震形成了2个重灾区,即班图尔(Bantul)重灾区和克拉特恩(Klaten)重灾区;(2)建筑物结构不合理、建筑物质量和材质差,建筑物抗震性能差,灾区场地环境不良,加之灾区人口密度大和地震发生在凌晨等,是此次小震大灾的主要原因;(3)对地震构造背景以及与默拉皮火山(Merapi Volcano)相关性进行了初步研究,提出此次地震与火山活动密切相关。     

Global Seismic Hazard Assessment Program maps are erroneous

The March 11, 2011 megathrust on the Pacific coast of the Tohoku Region, Japan, and its consequences once again confirmed the presence of evident problems in the conventional methodology of risk and earthquake loss evaluation. A systematic analysis shows that the results of the Global Seismic Hazard Assessment Program (GSHAP, 1992–1999) contradict the actual occurrence of strong earthquakes. In particular, since the publication of the GSHAP final results in 1999, all 60 earthquakes with magnitudes of 7.5 or higher were “surprises” for the GSHAP maps. Moreover, in half of the cases they were “big surprises,” when instead of the expected “light” or “moderate,” “significant” or even “total” destruction took place. All twelve of the deadliest earthquakes happened in 2000–2011 (total number of deaths exceeded 700000 people) prove that the GSHAP results, as well as underlying methodologies, are deeply flawed and, evidently, unacceptable for any critical risk assessments entitled to prevent disasters caused by earthquakes.     

Probabilistic Seismic Hazard Assessment for Izmir, Turkey

Izmir, the third largest city and one of the major economic centers in Turkey, has more than three million residents and one-half million buildings. The city, located in a seismically active region in western Anatolia, was a subject of the 1997 RADIUS (Risk Assessment Tools for Diagnosis of Urban Areas against Seismic Disaster) project. In this paper, the seismic hazard of Izmir is investigated through probabilistic seismic hazard assessment. First, the seismic setting of Izmir is presented. Considering the statistics of earthquakes that took place in the region during the period 1900–2005, a simple seismic hazard model is used to facilitate the assessment. To account for modeling uncertainties associated with the values of seismicity parameters, a logic tree procedure is employed in carrying out the seismic hazard computations. The resulting weighted average seismic hazard, presented in terms of peak ground acceleration and associated probability of exceedence, could be considered the “best estimate” of seismic hazard for Izmir. Accordingly, for a return period of 475 years, for rock sites, a PGA value of 0.34 g is calculated. This PGA hazard estimate is close to the current code-recommended design acceleration level for Izmir.