平抚社会恐震心理化解预报科普困扰

一次具有社会影响的地震发生之后,很多人会问为什么,意即在这个地方、这个节骨眼儿,为啥会发生这样大小的地震?为及时回应社会关切,地震分析预报工作者或专家往往尽其所能在第一时间给出比较科学的解释,诸如"余震说""构造说""能量说".可是不少公众并不买账,提出更多问题或多方质疑,甚至伴随讽刺和调侃.例如,2020年"7?12...     

Efficient testing of earthquake forecasting models

Computationally efficient alternatives are proposed to the likelihood-based tests employed by the Collaboratory for the Study of Earthquake Predictability for assessing the performance of earthquake likelihood models in the earthquake forecast testing centers. For the conditional L-test, which tests the consistency of the earthquake catalogue with a model, an exact test using convolutions of distributions is available when the number of earthquakes in the test period is small, and the central limit theorem provides an approximate test when the number of earthquakes is large. Similar methods are available for the R-test, which compares the likelihoods of two competing models. However, the R-test, like the N-test and L-test, is fundamentally a test of consistency of data with a model. We propose an alternative test, based on the classical paired t-test, to more directly compare the likelihoods of two models. Although approximate and predicated on a normality assumption, this new T-test is not computer-intensive, is easier to interpret than the R-test, and becomes increasingly dependable as the number of earthquakes increases.     

Evaluation of numerical earthquake forecasting models

Evaluation of numerical earthquake forecasting models needs to consider two issues of equal importance: the application scenario of the simulation, and the complexity of the model. Criterion of the evaluation-based model selection faces some interesting problems in need of discussion.     

华东地区具有短期预测意义的特殊显著性地震事件识别

依据华东地区中强地震前的地震活动特点,初步提出“特殊显著性地震事件”SPE的概念及其可能的识别方法.具有前兆指示意义的SPE可划分为三类,三类SPE分别表达了主震前中小地震与主震之间的时空位置关系.I类SPE距主震时、空距离均较近,在一定程度上与“直接前震”具有相似之处;II类SPE距主震时间较近、而空间距离可能较远,但与主震之间有一定的构造联系,具有时间上的“信号地震”的意义.Ⅲ类必须首先通过地震活动性方法对可能的SPE进行筛选,之后通过比较其与之前在同一位置发生的一系列中小地震的地震波参数之间的差异,在一定程度上进一步确认其短期预测意义.华东6次中强地震震例的研究结果表明,当可能的SPE的单台波速比小于此前该区域长时期的均值、归一化尾波持续时间大于此前该区域长时期的均值以及振幅衰减系数与此前该区域长时期均值之差大于长时期均值的30％时,可进一步认定其短期前兆意义.     

Research status of earthquake forecasting in hydraulicfracturing induced earthquakes

In the new types of industrial activities including unconventional energy extraction associated with shale gas and hot dry rock, gas reservoir operations, CO2 geological storage, undergoing research on induced earthquake forecasting has become one of the forward positions of current seismology. As for the intense actual demand, the immature research on induced earthquake forecasting has already been applied in pre-assessment of site safety and seismic hazard and risk management. This work will review systematically recent advances in earthquake forecasting induced by hydraulic fracturing during industrial production from four aspects: earthquake occurrence probability, maximum expected magnitude forecasting, seismic risk analysis for engineering and social applications and key scientific problems. In terms of earthquake occurrence probability, we introduce statistical forecasting models such as an improved ETAS and non-stationary ETAS and physical forecasting models such as Seismogenic Index (SI) and hydro-mechanism nucleation. Research on maximum expected magnitude forecasting has experienced four stages of linear relationship with net injection volume of fluid, power exponential relationship and physical forecasting regarding fault parameters. For seismic risk analysis, we focus on probabilistic seismic hazard assessment and quantitative geological susceptibility model. Furthermore, this review is extended to key scientific problems that contain obtaining accurate fault scale and environmental stress state of reservoir, critical physical process of runaway rupture, complex mechanism of fault activation as well as physical mechanism and modeling of trailing effect. This work in understanding induced earthquake forecasting may contribute to unconventional energy development and production, seismic hazard mitigation, emergency management and scientific research as a reference.     

以菏泽地震为例探讨地震学综合预测方法

在前人提出的地震预测方法基础上提出一种地震学综合预测方法。 首先利用动态图像方法(地震条带与地震空区)大致确定潜在地震危险区; 然后利用中、 强地震产生的库仑应力确定孕震区; 最后利用地震矩快速释放模型和相关长度增长模型判断孕震区是否进入短临状态。 在地震三要素预测中, 发挥地震学典型预测方法的优势, 并且对相关性较小的预测方法的预测结论相互对比、 印证, 以便得出更可靠的预测结果。 文中还利用这种综合预测方法对1983年菏泽5.9级做了简略研究, 结果表明这种综合预测方法的预测结果和菏泽地震基本上是一致的。     

Stochastic response of suspension bridges to earthquake forces

The purpose of the paper is to study the applicability of stochastic methods for determining the response in the vertical plane of long-span bridges to earthquakes. The bridges are of the modern type, with flexible towers, box-decks and inclined hangers, Humber and Bosporus being used as the main examples, although some useful information is obtained by studying a small suspension footbridge. The input ground acceleration is that of the Pacoima Dam record of the 1971 San Fernando event, but use is also made of filtered white noise. Because the stochastic approach is essentially an attempt to abstract usable information which could otherwise be obtained from a lengthy time-history approach, the procedure adopted here is to compare the same parameters obtained in these two ways, as far as possible. In particular, the maximum values of displacements and bending moments are considered. The essential question to be answered is whether the short length of earthquake records, coupled with the large natural periods of vibration of long-span bridges, allows sufficient response information to be generated to make statistical parameters meaningful. The short-span (50 m) footbridge gives no cause for concern here, but the detailed comparison with time-history solutions shows that the stochastic approach for both Bosporus and Humber has to be cautiously assessed, particularly if some trailing zeros are not added to the earthquake record. However, general conclusions are not made, because only one earthquake record has been used.     

Operational earthquake forecasting in Europe: progress,despite challenges

Is Europe-wide operational earthquake forecasting (OEF) possible? We discuss the myriad problems that prevent it today, many of which relate to heterogeneities in earthquake recording, processing, and reporting. We contemplate the difficulty of building models that cross political boundaries, and we consider the prospect of European OEF in light of recent efforts to harmonize long-term seismic hazard assessment among several nations. Emphasizing the Strategies and Tools for Real-time Earthquake Risk Reduction (REAKT) project, we report achievements related to short-term seismicity forecasting in Iceland and Italy that could apply elsewhere in Europe. In Iceland, collaboration fostered by REAKT resulted in a revised earthquake catalog and a prototype OEF system. We report results from an experiment conducted with this prototype; these results suggest ensemble models provide an information gain, updating models more frequently improves their forecast skill, and that OEF is computationally feasible. In Italy, REAKT supported the creation of an ensemble model that now issues weekly hazard forecasts. We present examples of these forecasts, highlighting the problem that OEF often yields low probabilities, which are difficult to interpret and convert into actionable decisions. Motivated by such low hazard probabilities, we highlight Europe’s pioneering efforts in operational earthquake loss forecasting and mention solutions to problems that currently prevent OEF at the European scale.     

System identification of the Vincent Thomas suspension bridge using earthquake records

The Vincent Thomas Bridge in the Los Angeles metropolitan area, is a critical artery for commercial traffic flow in and out of the Los Angeles Harbor, and is at risk in the seismically active Southern California region, particularly because it straddles the Palos Verdes fault zone. A combination of linear and non‐linear system identification techniques is employed to obtain a complete reduced‐order, multi‐input–multi‐output (MIMO) dynamic model of the Vincent Thomas Bridge based on the dynamic response of the structure to the 1987 Whittier and 1994 Northridge earthquakes. Starting with the available acceleration measurements (which consists of 15 accelerometers on the bridge structure and 10 accelerometers at various locations on its base), an efficient least‐squares‐based time‐domain identification procedure is applied to the data set to develop a reduced‐order, equivalent linear, multi‐degree‐of‐freedom model. Although not the main focus of this study, the linear system identification method is also combined with a non‐parametric identification technique, to generate a reduced‐order non‐linear mathematical model suitable for use in subsequent studies to predict, with good fidelity, the total response of the bridge under arbitrary dynamic environments. Results of this study yield measurements of the equivalent linear modal properties (frequencies, mode shapes and non‐proportional damping) as well as quantitative measures of the extent and nature of non‐linear interaction forces arising from strong ground shaking. It is shown that, for the particular subset of observations used in the identification procedure, the apparent non‐linearities in the system restoring forces are quite significant, and they contribute substantially to the improved fidelity of the model. Also shown is the potential of the identification technique under discussion to detect slight changes in the structure's influence coefficients, which may be indicators of damage and degradation in the structure being monitored. Difficulties associated with accurately estimating damping for lightly damped long‐span structures from their earthquake response are discussed. The technical issues raised in this paper indicate the need for added spatial resolution in sensor instrumentation to obtain identified mathematical models of structural systems with the broadest range of validity. Copyright © 2003 John Wiley & Sons, Ltd.     

唐山市新区预测震害烈度的确定

通过分析唐山市新区地震地质资料、历史地震资料并结合唐山大地震与强余震的分布规律等，综合确定唐山新区预测震害烈度，为房屋震害预测分析提供依据。     

震情会商的意义与主持地震会商应注意的几个问题

本文阐述了震情会商的意义,强调凡责任重大的经验性预报都得会商.并根据经验,分析了会商主持人应具备的素质与主持会商应注意的几个问题.     

地震信息通信网络系统在地震监测预报中的应用

地震信息通信网络系统的建立是防震减灾技术系统建设中的重要内容 ,本文结合实际工作 ,就计算机通信网络系统的构成、主要技术性能以及在实施过程中需要解决的一些技术问题进行探讨 ,同时对网络系统在地震监测预报工作中的应用情况作一简要介绍     

Operational earthquake loss forecasting: a retrospective analysis of some recent Italian seismic sequences

Operational earthquake forecasting (OEF) relies on real-time monitoring of seismic activity in an area of interest to provide constant (e.g., daily) updates of the expected number of events exceeding a certain magnitude threshold in a given time window (e.g., 1 week). It has been demonstrated that the rates from OEF can be used to estimate expected values of the seismic losses in the same time interval OEF refers to. This is a procedure recently defined as operational earthquake loss forecasting (OELF), which may be the basis for rational short-term seismic risk assessment and management. In Italy, an experimental OELF system, named MANTIS-K, is currently under testing. It is based on weekly rates of earthquakes exceeding magnitude (M) 4, which are updated once a day or right after the occurrence in the country of an M 3.5+ earthquake. It also relies on large-scale structural vulnerability and exposure data, which serve to the system to provide continuously the weekly expected number of: (1) collapsed buildings, (2) displaced residents, and (3) casualties. While the probabilistic basis of MANTIS-K was described in previous work, in this study OELF is critically discussed with respect to three recent Italian seismic sequences. The aim is threefold: (1) illustrating all the features of the OELF system in place; (2) providing insights to evaluate whether if it would have been a useful additional tool for short-term management; (3) recognizing common features, if any, among the losses computed for different sequences.     

2021年青海玛多MS7.4地震余震预测及效能检验

1 研究背景 2021年5月22日青海玛多地区发生MS 7.4地震,中国地震局针对此次地震快速组织开展了科学考察工作.根据科考阶段性成果交流形成的统一认识,玛多MS 7.4地震的发震断层为昆仑山口—江错断裂,地表破裂段为该断裂东段,即江错断裂段.为对震后震情形势进一步研判以及为前线科考人员提供"跟踪式"科技支撑,此次科考中对余震趋势评估成为一项重要工作内容.     

基于可公度方法的云南地区地震数据分析与预测

基于可公度的方法,对云南地区（22°～29°N,98°～104°E）从1800到2007年间发生的震级在6．7级以上的地震数据进行了分析与预测。在证实该数据具有较强的可公度性的基础上,预测云南地区近期的地震发生时间,获得了较好的结果。因此,将该方法用于地震,水文等数据的处理,对防灾减灾是非常有意义的。     

关于1 933年叠溪7.5级地震若干问题的讨论

１９３３年叠溪７．５级地震是本世纪发生于青藏高原东缘的重大事件。对这次地震,不同部门曾进行考察,但给出的等烈度线图有着明显的分歧。这一分歧意味着对该次地震构造认识的不同。本文基于对该次地震的震害特征、震中位置,震中区地质构造环境以及发震构造的讨论,认为南北向的活动断裂有可能是该次地震的发震构造,而该活动断裂可能是岷江断裂的南延。     

2021年青海玛多MS7.4地震余震预测及效能检验

1 研究背景 2021年5月22日青海玛多地区发生MS 7.4地震,中国地震局针对此次地震快速组织开展了科学考察工作.根据科考阶段性成果交流形成的统一认识,玛多MS 7.4地震的发震断层为昆仑山口—江错断裂,地表破裂段为该断裂东段,即江错断裂段.为对震后震情形势进一步研判以及为前线科考人员提供"跟踪式"科技支撑,此次科考中对余震趋势评估成为一项重要工作内容.     

建筑物地震保险的若干问题

将商业保险引入建筑物防震减灾是减少地震损失的一种有效经济手段。对建筑物地震保险进行讨论,对地震保险的形式、承保—理赔机制、保险基金等主要问题作了详细的阐述,建议将年震害期望损失比作为纯费率厘定的主要原则,同时以未来一段时间内的最大期望损失率估算地震保险基金的规模。     

Loss forecasting of earthquake fire based on radial basis function network

Introduction The earthquake fire is one of main hazards in subsequent hazards of earthquake, which caused much severer damage than the ground motion itself. So it is significant to evaluate and predict loss of earthquake fire as a part of hazard of earthq…     

某些震源问题的讨论

震前预滑是预报大震的物理基础之一。在强的构造压力作用下形成的震源,预滑较显。在构造引张作用下形成的震源,预滑易和发震本身紧连在一起。大地震（Ｍ≥７）发生时在地表形成的错动可分三种类型：第一种是在震中区局部地段有错动;第二种是在地表与震源长度相当的地段有锚动但中间部位位移较在;第三种是在地表与震源长度相当的地段有错动但位移在以处几乎相当。按照组合模式,可将地震前兆分为震源区前兆、调整单元和调整场区