Correlation of Static Stress Changes and Earthquake Occurrence in the North Aegean Region

A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. The earthquake data set comprises all events of magnitude M ≥ 5.2 which have occurred since 1964. This is compared to the evolving stress field due to constant tectonic loading and perturbations due to coseismic slip associated with major earthquakes (M ≥ 6.4) over the same period. The stress was resolved for sixteen fault orientation classes, covering the observed focal mechanisms of all earthquakes in the region. Analysis using error diagrams shows that earthquake occurrence is better correlated with the constant tectonic loading component of the stress field than with the total stress field changes since 1964, and that little, if any, information on earthquake occurrence is lost if only the maximum of the tectonic loading over the fault orientation classes is considered. Moreover, the information on earthquake occurrence is actually increased by taking the maximum of the evolving stress field since 1964, and of its coseismic-slip component, over the fault orientation classes. The maximum, over fault orientation classes, of linear combinations of the tectonic loading and the evolving stress field is insignificantly better correlated with earthquake occurrence than the maximum of the tectonic loading by itself. A composite stress-change variable is constructed from ordering of the maximum tectonic loading component and the maximum coseismic-slip component, in order to optimize the correlation with earthquake occurrence. The results indicate that it would be difficult to construct a time-varying earthquake likelihood model from the evolving stress field that is more informative than a time-invariant model based on the constant tectonic loading.     

Retrospective Forecasting of M ≥ 4.0 Earthquakes in New Zealand

We have applied a variation of the Epidemic Type Aftershock Sequence (ETAS) model, which is a stochastic triggering epidemic model incorporating short-term clustering, to data collected by the New Zealand Seismological Observatory-Wellington (Geonet) for forecasting earthquakes of moderate and large magnitude in the New Zealand region. The model uses earthquake data only, with no explicit use of tectonic, geologic, or geodetic information. In this epidemic-type model every earthquake is regarded, at the same time, as being triggered by previous events and triggering following earthquakes. A maximum likelihood estimate of the model parameters has been performed on the learning period from 1960 to 2005 for earthquakes of magnitude 4.0 and larger. Forecast verification procedures have been carried out in a forward-retrospective way on the January 2006 to April 2008 data set, making use of statistical tools as the log-likelihood ratio, the Relative Operating Characteristics (ROC) diagrams, the Molchan error diagrams, the probability gain and the R-score. These procedures show that the clustering epidemic model achieves a log-likelihood ratio per event of the order of some units, and a probability gain up to several hundred times larger than a time-independent spatially uniform random forecasting hypothesis. The results show also that a significant component of the probability gain is linked to the time-independent spatial distribution of the seismicity used in the model.     

水氡动态图强震危险区预测的新方法

水氡动态图强震危险区预测法是一种地下流体的地震分析预报新方法。 对该方法做了系统的介绍,其内容有: 水氡基值变化率动态图像的生成方法,水氡变化率高值异常区图形演化与地震震中位置的关系,强震危险区预测的标志与方法。检验性预测结果表明,该方法具有预测效能,可在实际地震预报中使用。     

Two kinds of moment ratio diagrams and their applications in hydrology

We refocus attention on moment ratio diagrams and their uses in hydrology with four major objectives: (1) to summarize the information available in the literature about possible uses of the traditional moment ratio diagram introduced by Karl Pearson, which uses the coefficient of skewness and of kurtosis to compare the shapes of various distributions commonly used in hydrology; (2) to complete this traditional MRD by integrating into it the regions occupied by the log-Pearson Type III and generalized gamma distributions which are more and more used in hydrology; (3) to present another MRD which uses ratios of moments of orders –1 (harmonic mean), quasi zero (geometric mean) and 1 (arithmetic mean); (4) to stress the need to consider the different MRD's (along with the more recently introduced L-moment ratio diagrams) as complementary tools for choosing between distributions fitted to hydrologic data. Finally, using Monte Carlo simulation we compare the two types of diagrams as tools to identify and discriminate between different distributions.     

基于PCA的地震官方微博影响力评价研究

随着政务微博用户规模及影响力的不断提升,微博作为地震部门传播平台,在地震信息传播方面发挥着巨大的作用。本文在充分考虑地震部门行业特点的基础上,对30个地震官方微博数据进行收集,利用主成分分析法(PCA)归纳出3种地震微博的主要影响指标,即服务力主成分、交互力主成分和创作力主成分,并由此构建出地震官方微博影响力评估指标体系,在此基础上计算得出各地震官方微博的主成分指标得分和影响力综合得分,最后根据得分情况对地震官方微博影响力提出了具可行性的提升策略。     

水化学分析方法在地下水异常核实中的应用

地震前兆识别中的异常核实工作是提高地震分析预报能力的重要环节。"四图一法"是地下水异常核实中有效的水化学分析方法,其中Piper图和Schoeller图用于判定地下水化学类型和补给关系,Gibbs图用于判定地下水化学成分来源,Giggenbach三角图用于判定地下水的水岩平衡状态和是否有深部活动信息,以及混合比例法用于计算地下水的混合程度。同时,介绍了水化学分析方法在异常核实应用中的水样采集、测试方法和基本原理。使用水化学分析方法,有助于判定异常的构造或非构造活动影响因素,提高异常判定的科学水平。     

阿克苏断层氢气浓度动态特征及其映震效能

首先对阿克苏断层氢气浓度观测资料的周期成分进行了时频分析,然后分别利用线性回归和互相关方法分析了气温、气压与氢气浓度年周期成分的关系,并利用Molchan图表法对阿克苏断层氢气的映震效能进行了定量检验。结果显示:① 阿克苏断层氢气浓度具有清晰的年周期和半日周期成分;② 阿克苏断层氢气浓度的年周期动态变化与气温具有显著的正相关性,与气压的相关性一般,表明其年周期变化主要受气温影响;③ 阿克苏断层氢气浓度异常对观测点周边中强以上地震的反应较灵敏,映震效果较好。      

山东数字化水位观测资料与模拟观测资料的对比分析

山东数字化水位观测开展了近3年时间，与模拟观测相比，具有数据传输快、数据量级大、人为误差少的优点，从而使地下水位的高频、短周期信息大量增加，为捕捉地震短临异常信息提供了有利条件。分析结果表明，数字化水位观测资料与模拟观测资料的变化特征一致，因而可以代替现有的模拟观测；数字化水位观测资料保存在SQLserver数据库，可通过地震前兆信息处理与软件系统（EIS2000）方便地联接，随时采用相关的数学处理方法分析，跟踪动态的发展变化；日常分析应用表明，数字化水位观测资料仍可延用以往模拟观测资料的分析处理方法，同时许多新方法（如潮汐分析、加卸载响应比法）也可在数字化水位观测资料分析中应用。     

防震减灾科普需求和满意度调查指标设计及结果分析

本文针对2020年全国公众防震减灾科普满意度调查工作,设计了防震减灾科普公众接触率、受众收获评价、公众满意度和需求等指标,量化衡量防震减灾科普在公众中的触达现状、公众的收获评价、反馈评价和需求.调查结果显示,公众与防震减灾科普的接触较普遍,受众收获评价和满意度评价总体得分较高.防震减灾科普公众接触率在不同城乡、年龄、学...     

基于Vague集的建筑物地震倒塌率研究

介绍了相似度量及地震事件的建筑物破坏相似因素分析,并在此基础上建立了基于相似度量的建筑物地震倒塌率的预测函数.最后,以历史地震事件统计数据为基础,根据假设检验理论得出了预测误差与相似度量的关系.     

地震预警连续定位方法研究

本文首先总结了地震预警系统中采用的一些实时定位方法,随后结合我国地震监测台网实际运行情况,提出了一套从单个台站触发开始逐渐过渡到利用前四台触发信息的完整地震预警连续定位方法.利用福建省地震监测台网记录的68个M3.0级以上地震观测记录,对本文方法的验证结果表明,对于网内地震,采用本文方法的单台定位结果误差均小于为50 km,双台定位结果误差均小于35 km,三台定位结果误差约为15 km,四台定位结果误差约为6 km;网外地震的三台、四台定位结果误差均小于30 km.推导了采用本文三、四台预警定位方法的误差公式.利用福建地区现有及"十一五"完成后的地震观测台网分别计算得到了定位误差分布图.根据误差分析结果即可对定位结果的可靠性预先做出判断,有利于提高地震预警系统运行的可靠性.     

地震应急全时程灾情汇聚与决策服务技术研究

针对震前灾情难以预估,震后灾情获取缓慢且碎片化,灾情评估误差较大,决策支持不到位,灾情服务缺位等科学问题,综合考虑震前应急准备和灾后应急处置场景,重点研究全时程灾情与决策信息获取和分析手段,震后灾情信息实时汇聚与融合技术,震后基于致死性和易损性相结合的损失综合分析技术,不同区域辅助决策支持要点,面向多用户灾情信息服务产品可视化生成技术,建立灾情推送与信息准实时服务平台及终端,构建基于云架构的智能化、可视化地震应急信息全流程服务平台,开展应急协同服务示范,实现7级以上大地震灾情信息全时程服务。该项目将丰富地震灾情信息获取手段,形成涵盖灾情收集、信息速报、监测预警、分析评估、智能协同和动态发布等地震应急全过程技术平台,提升地震应急信息服务能力,对快速、科学施救具有重要意义。      

Relative model score: a scoring rule for evaluating ensemble simulations with application to microbial soil respiration modeling

This paper defines a new scoring rule, namely relative model score (RMS), for evaluating ensemble simulations of environmental models. RMS implicitly incorporates the measures of ensemble mean accuracy, prediction interval precision, and prediction interval reliability for evaluating the overall model predictive performance. RMS is numerically evaluated from the probability density functions of ensemble simulations given by individual models or several models via model averaging. We demonstrate the advantages of using RMS through an example of soil respiration modeling. The example considers two alternative models with different fidelity, and for each model Bayesian inverse modeling is conducted using two different likelihood functions. This gives four single-model ensembles of model simulations. For each likelihood function, Bayesian model averaging is applied to the ensemble simulations of the two models, resulting in two multi-model prediction ensembles. Predictive performance for these ensembles is evaluated using various scoring rules. Results show that RMS outperforms the commonly used scoring rules of log-score, pseudo Bayes factor based on Bayesian model evidence (BME), and continuous ranked probability score (CRPS). RMS avoids the problem of rounding error specific to log-score. Being applicable to any likelihood functions, RMS has broader applicability than BME that is only applicable to the same likelihood function of multiple models. By directly considering the relative score of candidate models at each cross-validation datum, RMS results in more plausible model ranking than CRPS. Therefore, RMS is considered as a robust scoring rule for evaluating predictive performance of single-model and multi-model prediction ensembles.     

利用三维高斯射线束成像进行地震定位

常规的地震定位方法通常需要拾取地震记录的初至,当初至不明显或被较高水平的噪声淹没时精度较低.本文采用基于三维高斯射线束的偏移成像方法对震源进行定位,较好地解决了该问题.通过三维高斯射线束对台站记录进行偏移归位,并将各台站成像结果的交点作为地震能量释放的中心位置;当各台站成像结果不能交于一点时,采用三维空间高斯滤波方法可实现震源位置的自动获取.提出的变网格计算方案极大地减少了计算量,显著地提高了成像精度和计算效率.利用首都圈地震台网数据,对涿鹿、滦县以及房山三个地震事件进行试算,结果表明:基于变网格三维高斯束偏移成像的地震定位方法自动化程度很高,而且具有较好的抗噪能力,特别适合处理低信噪比资料的地震定位问题.     

年滑动速率比方法在跨断层形变资料分析中的应用

根据跨断层形变观测资料变化特点提出了年滑动速率比方法, 用于消除观测资料中的粗差、 正常年动态和线性趋势变化成分, 突出观测资料中的非正常变化信息, 以便统一在无量纲的基准下综合分析区域内断层活动水平。 以2013年4月20日芦山7.0级地震前四川跨断层形变年滑动速率比异常为例, 说明该方法在地震分析预报研究中具有比较好的可行性和实用性。     

应变能积累在地震安全性评价中的应用探讨

理论及实验研究显示,震源区的位置和最大震级不仅可能与构造和历史有关,更重要的是与应力状态包括其方向、大小、增加速率、集中位置等以及岩体自身性质,包括其强度、杨氏模量、应变大小及增长速率、裂缝(断层)大小和数量等有关,同时与作用方式有关.综合考虑各种因素,探讨了利用应变能积累确定强震位置和震级的方法:首先对利用形变空间特征变化判断强震震源区位置的方法进行了讨论;接着着重提出估算应变能的初步方法:一是由地表裂缝最大错距和裂缝(断层)长度比估算地震释放能量;二是由新构造运动分区块体体积、年平均应变速率及杨氏模量估算块体应变能积累;进而依据能量估算地震震级;最后以实例论述了应变能积累过程及特点对地震安全性评价的重要作用.     

A study on damage scenarios for residential buildings in Catania city

The main purpose of this study is to obtain the damage scenario for residential buildings in the occurrence of a destructive earthquake (M = 7+) in the city area of Catania, Eastern Sicily, and to illustrate the comparative performance of two alternative methods used for this purpose. The methods are representative of two different approaches to estimating the seismic vulnerability of structures, i.e., an empirical approach based on statistical score assignments (widely used in Italy and other countries) and a more recent, mechanical approach that uses displacement limit states associated with well-defined thresholds of structural damage. A special concern for seismic vulnerability in Catania is caused by the fact that earthquake design norms were enforced in its municipal area only since 1981. We emphasise some typical problems encountered in earthquake scenario work, such as the difficulty of assembling a reliable building inventory, and the uncertainties inherent in the vulnerability assessments through different probabilistic assumptions. Different criteria for the representation of damage are applied and discussed. It is shown that the main scenarios obtained by the two methods are in reasonable agreement, provided a suitable percentile level for damage is chosen in the statistical score assignment approach.     

Space–Time Earthquake Prediction: The Error Diagrams

The quality of earthquake prediction is usually characterized by a two-dimensional diagram n versus τ, where n is the rate of failures-to-predict and τ is a characteristic of space–time alarm. Unlike the time prediction case, the quantity τ is not defined uniquely. We start from the case in which τ is a vector with components related to the local alarm times and find a simple structure of the space–time diagram in terms of local time diagrams. This key result is used to analyze the usual 2-d error sets {n, τ _w } in which τ _w is a weighted mean of the τ components and w is the weight vector. We suggest a simple algorithm to find the (n, τ _w ) representation of all random guess strategies, the set D, and prove that there exists the unique case of w when D degenerates to the diagonal n + τ _w  = 1. We find also a confidence zone of D on the (n, τ _w ) plane when the local target rates are known roughly. These facts are important for correct interpretation of (n, τ _w ) diagrams when we discuss the prediction capability of the data or prediction methods.     

承德地震台VP型宽频带垂直摆运行效能分析

与VS型垂直摆各项参数进行对比,分析VP型宽频带垂直摆具有的优势。采用VS、VP型垂直摆记录资料,对比数据连续率、完整率及固体潮记录能力、同震变化等;分析VP型垂直摆精度、潮汐因子绝对误差、相位误差等,以偏离正常年变背景为基准,判断其数据记录是否异常,并分析年变特征,拟合观测数据分析异常特征,通过R值评分,进一步分析承德地震台VP型宽频带垂直摆映震能力。分析发现,VP型宽频带垂直摆记录固体潮和同震曲线的能力较好,精度较高,潮汐因子误差及绝对误差较小,产出数据更为可靠,异常信息更为明显,映震能力更高。     

Statistical prediction of the next great earthquake around Tehran,Iran

The analysis of seismic activity variations with space and time is a complex problem. Several statistical methods have been adopted to study these variations. One of the tasks that has attracted the attention of the seismological and statistical community is to explain seismicity patterns by statistical models and apply the results for earthquake prediction. Here the probability distribution of recurrence times as described by Exponential, Gamma, Lognormal, Pareto, Rayleigh and Weibull probability distributions and the idea of conditional probability has been applied to predict the next great (Ms ≥ 6.0 and Ms ≥ 6.5) earthquake around Tehran (r ≤ 200 km). Conditional probability specifies the likelihood that a given earthquake will happen within a specified time. This likelihood is based on the information about past earthquake occurrences in the given region and the basic assumption that future seismic activity will follow the pattern of past activity. The rapid growth of Tehran to approximately 12 million inhabitants has resulted in a much more rapid increase in its vulnerability to natural disasters, especially earthquakes. Several earthquakes affected this region in the past, mostly on the Mosha, Taleqan, Eyvankey and Garmsar faults. The estimated recurrence times for Exponential, Gamma, Lognormal, Pareto, Rayleigh and Weibull distributions has been computed to be 66.64, 14.79, 26.88, 2.37, 67.58 and 80.47, respectively. Accordingly, one may expect that a large damaging earthquake may occur around Tehran approximately every 10 years.