模糊聚类方法在湖北西部地震综合预测的应用

以近２３年来源北西部地区ＭＬ≥４．０级地震前内符检验有一定震兆异常显示的６项地震活动性参数作为指标,估计样本有震或无震类型（１－０）的从属度,判定预报样本所属类别。根据模型类分析方法对鄂西地区的地震进行综合预测研究,统计结果认为：模型聚类方法对鄂西地区ＭＬ≥４．０级地震的预测具有一定的效能。     

鲜水河地震带和松潘、龙门山地震带可能发生5级以上地震的模糊聚类分析

本文对鲜水河地震带和松潘、龙门山地震带未来半年内是否能发生5级以上的地震进行了多因子模糊聚类分析。介绍了应用系统模糊聚类分析方法的具体步骤。根据各单项预报手段预报效能的清理结果,选用了9项地震活动性及前兆手段为指标,分别建立了鲜水河地震带和松潘、龙门山地震带31个时段的半年预报样本。利用这些样本分别对两地震带半年内是否可能发生5级以上地震进行了模糊聚类分析判断,并对其预报效能作了评分。结果表明用模糊聚类分析方法进行综合预报的预报评分值明显高于各单项手段的预报评分值。     

地震形势的模糊综合评判

由中国大陆板块内部地震活动与其周缘地震活动的相关性,可以确定我国大陆未来地震活动的主体和地震活动高潮时间.在此基础上,本文进一步探讨用长时间、大面积的地震活动信息,对重点监测区未来地震作出时、空、强综合评判.全文分为三部分: 1.地震强度的预报.对于确定的能有效地估计未来地震强度的5项地震活动性指标,选择加权平均型的模糊综合评判方法,对监测区未来地震的震级给出明确的结果. 2.发震地点预报.对于扫描单元定义了反映b值时空变化的二项指标:b值异常次数A_y;和b值异常均值b_(yi).通过对二项指标空间分布的综合分析,可以估计未来地震发生的地点. 3.发震时间预报.把缺震时间T_l与b值回升时间T_(bu)作为描述大震前平静过程的二项定量指标.在对未来地震强度作出模糊综合评判后,可用T_l,T_(bu)二项指标综合推断监测区未来地震发生的时间. 总结的九个震例结果表明,该方法可使地震预报定量化、实用化,可以用于地震形势的预测和中、短期地震预报.     

地震形势的模糊综合评判

由中国大陆板块内部地震活动与其周缘地震活动的相关性,可以确定我国大陆未来地震活动的主体和地震活动高潮时间[1].在此基础上,本文进一步探讨用长时间、大面积的地震活动信息,对重点监测区未来地震作出时、空、强综合评判.全文分为三部分:1.地震强度的预报.对于确定的能有效地估计未来地震强度的5项地震活动性指标,选择加权平均型的模糊综合评判方法,对监测区未来地震的震级给出明确的结果.2.发震地点预报.对于扫描单元定义了反映b值时空变化的二项指标:b值异常次数A_yi;和b值异常均值b_yi.通过对二项指标空间分布的综合分析,可以估计未来地震发生的地点.3.发震时间预报.把缺震时间T_l与b值回升时间T_bu,作为描述大震前平静过程的二项定量指标.在对未来地震强度作出模糊综合评判后,可用T_l,T_bu二项指标综合推断监测区未来地震发生的时间.总结的九个震例结果表明,该方法可使地震预报定量化、实用化,可以用于地震形势的预测和中、短期地震预报.      

华北震后趋势判断的前兆综合指标与方法

在对华北邢台、渤海、海城、唐山、大同五大震例的各前兆学科震后变化进行分析的基础上,本文归纳出综合判断后续地震异常的3项定量指标与4项定性指标,还给出了模糊综合评判的方法并计算出符合实际的结果,当评判有震时又给出预报后续地震三要素的经验性判据.     

四川盆地南部某些子区构造发震能力的模糊聚类分析判别

本文在对四川盆地南部地区地震构造背景进行了特征研究的基础上,根据对类比研究区孕震构造条件分析的结果,选取12项与该地区地震发生关系密切的判别因子作为模糊聚类分析的指标,建立了该地区有震样本19个,无震样本21个。利用系统模糊聚类方法,对成都、荣县、荣昌、泸州、綦江、桐梓等子区的构造发震能力进行了模糊聚类分析判别,对这些区域的孕震震级给出了定量的结果。     

利用多手段异常项次预报我国大震的模糊聚类方法

选用我国大陆１９６９－１９９１年发生的１１次Ｍｓ≥６．９地震作为样本，取地球物理、地球化学、地形变和地震活动性方面共计１２项手段的资料为判定指标，编制了模糊聚类计算机程序用以预报未来３个月、６个月和１２个月内发生大震的概率，并给出一个预报实例。     

基于多手段异常结果的地震综合概率预测

地震综合预测是,根据地震地质、地震活动性、地震前兆异常和环境因素等多种分析手段,与前兆信息监测所进行的现代防震减灾研究.最初的综合预测方法主要以预报经验的数学化统计为主,主要包含测震学、地壳形变学、地磁地电、地下流体等4种学科的预测方法,以及衍生出的,如综合概率法、模糊聚类、模式识别、专家系统以及模糊综合判定等分析方法...     

模糊数学方法在地震预测中的应用研究及其实效

20世纪80年代以来,针对地震孕育期间孕震信息的模糊性,国内开展了多项模糊数学方法在地震预测中的应用研究。应用这些方法可以将多项指标所显示的孕震的模糊信息转化为清晰的地震预测结果。现仅介绍模糊聚类分析和模糊综合评判两种常用方法在地震预测中的应用研究概况及其预测实效。     

模糊集理论与灰色系统理论在地震预报中的综合应用

把研究不确定信息的两种理论方法,即模糊集理论与灰色系统理论的方法综合应用于地震预报当中,在以下三方面取得了初步研究结果:(1)地震预测的灰色模糊模型.在灰色系统理论 GM(1.1)模型的基础上,把模糊数学的表达方式和灰色突变预测结合在一起,建立了地震预测的灰色模糊模型,为地震预报实用化提出了一种新的可能的途径,并给出了初步应用实例;(2)地震模糊聚类预测中指标优劣的灰色建模判断.仍以 GM(1,1)灰色建模为基础,在模糊聚类分析之前作指标择优处理,减少了指标选择的盲目性.以1975年以来江苏及其邻区的地震活动资料为例,进行了分析计算,结果比较清晰,比一般模糊聚类结果有所改进:(3)关联度和模糊聚类在地震预报中的联合应用.把灰色系统理论中的关联度方法和模糊集理论中的模糊聚类分析方法,联合应用于地震预报研究当中,以华北地区每年地震强度预测为例进行了初步探讨.本文的初步研究结果表明,地震预报所依据的不少信息和指标都带有灰色模糊的性质,因而,综合使用模糊集理论与灰色系统理论的方法可望取得更为有效的结果.      

Research on the principle and methodology of seismic zonation

Based on the cognizance of the temporal-spatial inhomogeneity of seismicity in North China, adopting the results of earthquake prediction in the past two decades and the currently used methods of seismic hazard analysis, and after some zonation trials in North China, some improvements on the zonation principle and methodology were made:

1. Seismic zones were taken as statistic units where seismicity parameters were obtained. Tendency analysis was introduced. Earthquake annual average occurrence rates were estimated corresponding to the seismicity level in the future period;
2. Average annual earthquake occurrence rates for a given magnitude interval of a specific seismic zone were assigned to potential sources considering the relative risk level among these sources. Thus, the risk of great earthquakes can be estimated.
3. The probabilistic spatial distribution function under the condition of magnitude interval was suggested to reflect the temporal and spatial inhomogeneity of seismicity.
4. An orientation function in the seismic hazard analysis model was adopted, which reflects the real condition of earthquake foci in China.

     

基于特大地震发生率的川滇地区地震危险性预测新模型

川滇地区是我国地震危险性较高的地区之一.本文基于对特大强震的风险性考虑,使用全球地震模型OpenQuake软件,建立了川滇地区地震危险性预测新模型.首先根据构造特征划分多个震源分区,并整理出这些震源分区内断层活动特征与滑动速率;基于震源分区和断层模型,使用GPS应变率转换成的锥形古登堡-里克特关系作为整个区域的地震积累率,并允许超过历史最大震级的特大地震的出现,结合活动断层滑动速率所积累的地震发生率,给出震源分区内断层地震源和背景地震源的地震发生率的比率分配关系;在活动断层分段上,保留了大型断裂或其主要部分,没有根据小的阶区来对断层进行详细分段,以便分配特大地震发生率;并使用地震率平滑方法分配背景地震发生率.最后在OpenQuake中加入地震动预测方程,计算出了川滇地区的PGA分布图,为区域地震危险性提供科学依据.     

Updated seismic hazard assessment of Tunisia

Modern earthquake loss models make use of earthquake catalogs relevant to the seismic hazard assessment upon seismicity and seismotectonic analysis. The main objective of this paper is to investigate a recently compiled catalog (National Institute of Meteorology or INM catalog: 412-2011) and to generate seismic hazard maps through classical probabilistic seismic hazard assessment (PSHA) and smoothed-gridded seismicity models for Tunisia. It is now established with the local earthquake bulletin that the recent seismicity of Tunisia is sparse and moderate. Therefore, efforts must be undertaken to elaborate a robust hazard analysis for risk assessment and seismic design purposes. These recommendations follow the recently published reports by the World Bank that describe the seismic risk in Tunis City as being beyond a tolerable level with an MSK intensity level of VII. Some attempts were made during the past two decades to assess the seismic hazard for Tunisia and they have mostly failed to properly investigate the historical and instrumental seismicity catalog. This limitation also exists for the key aspect of epistemic and random uncertainties impact on the final seismic hazard assessment. This study also investigates new ground motion prediction equations suitable for use in Tunisia. The methodology applied herein uses, for the first time in PSHA of Tunisia, seismicity parameters integrated in logic tree framework to capture epistemic uncertainties through three different seismic source models. It also makes use of the recently released version of OpenQuake engine; an open-source tool for seismic hazard and risk assessment developed in the framework of the Global Earthquake Model.     

判定潜在震源区的活断层模糊综合评判模型

确定潜在震源区及其震级上限是地震区划工作中的重要一环,而活断层的研究在这一领域中具有重要的意义。本文采用概率数理统计和模糊数学方法建立了活断层模糊综合评判模型,对活断层的定量化研究、潜在震源区研究中的不确定性分析以及充分反映地震活动的时空不均一性方面作了初步的探索性研究。并以华北地区为例进行了试算,取得了较好的结果     

地震区划原则和方法的研究——以华北地区为例.

本文基于对我国华北地区地震活动在时间和空间不均匀分布的认识,吸收了近20年来地震预测方面的科研成果,采用目前国际通用的地震危险性概率分析方法,通过对华北区划的试验,对地震区划的原则和方法提出了如下改进: 1.以地震带作为地震活动性参数的统计单元.引入地震活动趋势估计因素,评定表征地震活动水平的年平均发生率,以使区划结果同预测未来时间段地震活动水平相适应; 2.采用按震级挡次分配各潜在震源区的年平均发生率,可以合理地评估高震级地震的危险程度; 3.采用以震级挡次为条件概率的空间分布函数,刻画地震带内各潜在震源区之间发生相应震级挡次地震的相对危险程度,使区划结果更好地反映地震活动在时间和空间上不均匀性分布的特点; 4.在地震危险性分析计算中,引入了方向性函数项,使得分析模型更接近我国地震震源的实际情况.      

K-means cluster analysis and seismicity partitioning for Pakistan

Pakistan and the western Himalaya is a region of high seismic activity located at the triple junction between the Arabian, Eurasian and Indian plates. Four devastating earthquakes have resulted in significant numbers of fatalities in Pakistan and the surrounding region in the past century (Quetta, 1935; Makran, 1945; Pattan, 1974 and the recent 2005 Kashmir earthquake). It is therefore necessary to develop an understanding of the spatial distribution of seismicity and the potential seismogenic sources across the region. This forms an important basis for the calculation of seismic hazard; a crucial input in seismic design codes needed to begin to effectively mitigate the high earthquake risk in Pakistan. The development of seismogenic source zones for seismic hazard analysis is driven by both geological and seismotectonic inputs. Despite the many developments in seismic hazard in recent decades, the manner in which seismotectonic information feeds the definition of the seismic source can, in many parts of the world including Pakistan and the surrounding regions, remain a subjective process driven primarily by expert judgment. Whilst much research is ongoing to map and characterise active faults in Pakistan, knowledge of the seismogenic properties of the active faults is still incomplete in much of the region. Consequently, seismicity, both historical and instrumental, remains a primary guide to the seismogenic sources of Pakistan. This study utilises a cluster analysis approach for the purposes of identifying spatial differences in seismicity, which can be utilised to form a basis for delineating seismogenic source regions. An effort is made to examine seismicity partitioning for Pakistan with respect to earthquake database, seismic cluster analysis and seismic partitions in a seismic hazard context. A magnitude homogenous earthquake catalogue has been compiled using various available earthquake data. The earthquake catalogue covers a time span from 1930 to 2007 and an area from 23.00° to 39.00°N and 59.00° to 80.00°E. A threshold magnitude of 5.2 is considered for K-means cluster analysis. The current study uses the traditional metrics of cluster quality, in addition to a seismic hazard contextual metric to attempt to constrain the preferred number of clusters found in the data. The spatial distribution of earthquakes from the catalogue was used to define the seismic clusters for Pakistan, which can be used further in the process of defining seismogenic sources and corresponding earthquake recurrence models for estimates of seismic hazard and risk in Pakistan. Consideration of the different approaches to cluster validation in a seismic hazard context suggests that Pakistan may be divided into K?=?19 seismic clusters, including some portions of the neighbouring countries of Afghanistan, Tajikistan and India.     

一种应用于地震预报的概率判断法

从描述未来地震趋势的各种地震活动指标入手，在求得各样本组判别函数的基础上，由贝叶斯模型计算了不同时间尺度的地震活动性参数对未来地震趋势的概率判断结果。结果表明，在华北地区，地震活动性指标可以较早地反映地震孕育过程，所以，对地震活动性指标 提高预报准确性的可行途径之一。     

论发震构造特性在潜在震源区参数确定中的应用

发震构造特性是潜在震源区划分及其地震年发生率确定的重要依据。潜在震源区除了反映“未来具有发生破坏性地震的地区”的内涵外,还应反映高震级档地震具有相似复发特征的涵义。由于在地震活动性参数统计单元内,有一些具有不同本底地震的活动构造块体,为更好地反映地震活动的空间不均匀性,考虑潜在震源区的三级划分是有必要的。通过分析潜在震源区内高震级档地震的复发特征,计算预测时段内潜在震源区的高震级档地震的发震概率,采用预测时段内概率等效转换获得地震年平均发生率的方法,有助于在中国地震危险性分析框架内考虑潜在震源区的强震复发特性。另外,文中还对潜在震源区内特征地震次级震级档频度不足的特性和发震构造上强震非均匀性在地震危险性分析中的应用问题进行了探讨     

确定潜在震源区地震年平均发生率的方法研究

为了在地震危险性分析方法中,较好地反映大陆内部地震活动的时空不均匀性,按照震级分档和空间概率分布函数的思路,本文选取并量化了多个地震、地质特征,以描述各震级档地震活动在时间上和空间上的性质.为避免同一因素的重复使用和主观作用的介入,文中引入了分量分析方法对特征进行正交变换.对变换得到的互不相关的新特征进行模糊综合评判,再结合七级以上强震发生后的减震作用,确定了各潜在震源区各震级档的地震年平均发生率作为例子,试算了京-津-唐-张地区的地震烈度区划图.该例子说明,本文的分析方法,不仅能反映华北地区地震活动的时空不均匀性,还避免了特征量的重复使用和专家判断的影响      

Research on determining the annual earthquake occurrence rates of potential seismic source areas

To actually reflect the seismic temporal-spatial inhomogeneity of intra continental strong earthquakes of North China in seismic hazard analysis, several seismological and geological characteristics have been selected and quantized to describe the seismicity features in time and space of every magnitude interval with the thought of dividing the interesting magnitude range into several intervals and using of spatial probability distribution function. A component analysis method with orthogonal transformation is introduced to avoid the repeated use of the same element and the subjective effects in determining the annual earthquake occurrence rates of earthquake. By passing synthetic fuzzy judgement on the nonintercorrelated new characteristics, the annual occurrence rates of every magnitude interval of each potential source area are obtained associated with the adjustments of earthquake reducing process after the occurrence ofM>7 quake. An intensity map of the Beijing-Tianjin-Zhangjiakou area is calculated as an example which shows a close coincidence with the seismic temporal-spatial inhomogeneity of North China. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 496–504, 1991.